text:
Talk:Circuit breaker

"common trip" breakers
I modified the description of "common trip" breakers and took out the description of "low voltage". --Wtshymanski 19:21, 17 Dec 2004 (UTC)

 * I tweaked the description a little more with what I hope is better language explaining where two-pole, common trip breakers are used. By the way, does it conform to the code to tie two single-pole breaker handles together to try to form a common-trip breaker? Given "Free trip" mechanisms, I don't think you can assure that the handle tie will actually trip the "other" pole. I know I wouldn't want anything other than a true two-pole, common-trip breaker. Atlant 19:38, 17 Dec 2004 (UTC)

 * Yes, I like that much better. Of course you can have two-pole breakers on a 120/208V panelboard, or I suppose on a 240/415V board, or on a DC board. --Wtshymanski 19:40, 17 Dec 2004 (UTC)

Sorry don't have time to correct "(because RCDs need power to trip)", but the real reason is that they require a differential current to trip, which is higher than the typical lethal current flowing through a human (30ma vs 1ma potentially lethal current) — Preceding unsigned comment added by Fentlehan (talk • contribs) 22:32, 18 June 2012 (UTC)

Categories
Tiny circuit breakers, that you can put in a pocket, might be electronic components. Small breakers, that you can lift, maybe with the help of a friend,  might be found in electrical distribution. Big breakers, that show up in SCADA screens at system control centers, are pretty plainly electric power transmission devices. And the 30,000 amp breakers attached to generators are power components. Am I the only one finding the categorization of the article to be unclear? That's why I like the category electrical engineering- it fits anything with wires on it. Do the extra categories actually help Wikipedia users? --Wtshymanski 22:44, 8 May 2005 (UTC)

 * I agree. But you also need to look at how the categories are arranged.  It appears, for example, that Category:Electrical engineering includes as subcategories things like Category:Electric power and Category:Electrical components.  So maybe it shouldn't be in the supercategory on electrical engineering, but rather in several different subcategories under that.  I think that someone has been carried away with removing categories from several articles similar to this, but if there is problem itmay lie in a poorly thought out category structure. (Or the structure may be brilliantly arranged, I don't think I'm going to try to sort it all out, I'll let others put in their two cents' worth on that.)  Gene Nygaard 23:16, 8 May 2005 (UTC)

High-voltage Circuit breakers
I have completed the text with a description of interrupting principles used for HV circuit breakers (SF6 breakers as it is the technology now used for breakers 72,5 kV and above) Dingy 23 July 2005

 * Thanks for this addition!

 * Atlant 11:35, 25 July 2005 (UTC)

The images that illustrate the interrupting principles have been published in many publications or conference papers in India, France, China, Algeria.... there is no copyright, I am in fact close to the source.

Concerning the title "Internal details of a European breaker", now that the part on high-voltage circuit breakers is more developed I think that it is necessary to change the title to "Low voltage European Circuit breaker" or something like that..; dingy 26 July

 * Even if these images are not copyrighted, might it be a good idea to include a reference? I mention this especially because five of the six images used in the section "High-voltage circuit breakers" appear in one publication. The publication is: "Technical Trends in Circuit Breaker Switching Technologies", published in the CIGRE SC A3 Colloquium in Sarajevo, 2003. The authors are all listed as being from Alstom T&D (transmission and distribution). Although I have an electronic copy of the publication, online I have found referneces to it but no copy. Michapma, August 21

 * Good idea, you should do it Dingy 00:59, 22 August 2006 (UTC)

ELCBs and the USA
A comment in the article asked:

 * Were ELCBS that detect earth fault current directly ever used in the USA and if so what were they reffered to as?

If by ELCBs the questioner was referring to devices that measured, for example, the isolation between the power leads and ground/earth, then no, they have never been used in ordinary installations in the US. Because our power distribution systems almost always use a grounded neutral, there isn't any isolation to speak of.

Note that this is not true in specialized installations. For example, a large delta-connected motor, generator, or distribution circuit can certainly be isolated from ground and could be protected by an ELCB. Diesel-electric railroad locomotives frequently used just such an ELCB, energizing the traction motor circuits a small DC voltage away from ground and then measuring the current required to maintain that voltage (which ought to approach zero if the traction motor circuit was correctly isolated from the frame of the locomotive, but certainly became non-zero if, say, the traction motors became saturated with water).

But in ordinary practice, especially residential practice, it's all balance-fault interrupters.

Atlant 19:31, 17 July 2005 (UTC)
 * afaict what was reffered to as an ELCB in the uk had two seperate earth terminals and detected current flow between them. E.G. one terminal would be attached to the earthing system and one to the earth rod. I think they were only generally used on TT systems though.

There is one more use in the US. Installations over 250V to ground and 1200A require a variant of the ELCB. Normally, these use electronics and CT's to measure the current and react accordingly. — Preceding unsigned comment added by LightRobb (talk • contribs) 02:12, 21 January 2015 (UTC)

Switchgear?
I do not agree with this analysis. Circuit breakers in combination are called switchgears, which should be stated.

220.227.235.82

 * Well, this is Wikipedia so you know what to do: be bold!

 * Atlant 21:07, 14 August 2005 (UTC)

A circuit breaker is a type of Switchgear that is designed to break load current and extinguish an arc. Generally switchgear is the description given to any high voltage electrical switching equipment and covers a variety of equipment such as circuit breaker, air break switch disconnectors (ABSD's), earthing switches etc..

 * Switchgear is a general term covering switching devices and their combination. A circuit breaker is a switching device. You can conclude. Dingy (talk) 06:24, 4 August 2012 (UTC)

Close. Switchgear and switchboards are a type of CB installation. The CB's, and aux. equipment, are mounted in the gear or boards (I won't go into the differences here), and provide the required protection. You can also find fused switchboards, though they are a bit specialized. Note also that gear comes in both low (208V, 480V) voltage and high voltage flavors, boards are mostly low voltage. — Preceding unsigned comment added by LightRobb (talk • contribs) 02:15, 21 January 2015 (UTC)

high voltage
This page gives the impression that in high voltage engnineering cuircuit breaker means something somewhat different from what it means in low voltage wiring. in low voltage wiring a cuircuit breaker is something that detects a fault and automatically disconnects the supply. it seems in high voltage it means a device that breaks the cuircuit (which may be triggered by hardware sensing overcurrent that doesn't seem to be part of the breaker). Is this impression correct and if so should it be worked into the article somehow.

also the high voltage cuircuit breakers section is getting HUGE we should probablly break it out into a seperate article. Plugwash 16:43, 22 January 2006 (UTC)

 * That is correct. Any breaker rated in multiple KV will generally have a trip coil operated by external protective relays, which might be anything from electromechanical plunger-type relays up to digital (numeric) multi-function systems capable of significant programmability and complexity.  The "detection" and "interruption" are done in separate places, and if this is new to some then it's good that Wikipedia includes this data. Unluckily we've got a lot of electrical articles written at the home handyman level and as important as that level is in its own sphere, encyclopedia articles need to be more inclusive.

 * There's quit a lot on arc interruption but it is important and presents the fundamental issue in circuit breaker design. It's important to show the contrast between small breakers and large breakers...the illustration of the small Euro breaker is great. Bitty breakers are kind of dull..HV is cool.  --Wtshymanski 23:32, 22 January 2006 (UTC)
 * Hehe... well, it's electrical safety equipment. I don't think "being cool" is on the list of desired characteristics, unless you mean temperature-wise. Reliable to the point of boredom, now that's on there... 193.63.174.10 (talk) 11:26, 30 September 2010 (UTC)

I'm not saying we shouldn't keep some information on high voltage breakers here and it *IS* interesting but right now that section is bigger (in terms of rendered screenfulls) than the rest of the article combined. definately a case for sumarising and moving to a more specialist article. Plugwash 01:09, 23 January 2006 (UTC)

 * Hi, in the French version done later ("Disjoncteur à haute tension"), I made a separate article, a little more complete. The same could be done here, while keeping some text in this one. Dingy 04:02, 23 January 2006 (UTC)

Switching speed
"The double motion technique halves the tripping speed of the moving part" - I take this to mean that the total execution time has doubled? Perhaps the author meant tripping time instead?--Hooperbloob 08:05, 27 November 2006 (UTC)

 * sorry for my bad english, the meaning is as flows : if one contact (of a 245 kV breaker) moves you ned a speed of 8 m/s, if both contacts move in opposite direction, each needs a speed of 4 m/s (halved) in order to have the same relative speed of 8 m/s. Is it clear now ? Dingy 13:42, 27 November 2006 (UTC)

Type Of MCBs
Could anyone tell me where are we suppose to use Type B MCB, Type C MCB and so on...?

Let's say a 20A Type-B MCB is connected to a current carrying conductor. At what current will the MCB trip? Is it slightly above 20A or 3-5 times the rated current as stated in the article? —The preceding unsigned comment was added by LHW (talk • contribs) 10:30, 15 December 2006 (UTC). ll;'mkomikkpkoi hiu njhukj njmo

 * MCBs are thermal magnetic hybrids, the thermal part follows a smooth curve of faster tripping as current increases and deals with overloading but even in the best cases its pretty slow to trip. The magnetic part trips at the points given in the article and when it trips it trips as fast as the mechanism can physically move (iirc the standard says less than 100ms). Plugwash 01:11, 16 December 2006 (UTC)

 * Not all MCBs are thermal/magnetic. Last time I took apart a Square D "Q0" breaker, it was thermal-only.

 * Atlant 17:44, 16 December 2006 (UTC)

type B MCB can be used for domestic lighting purposes while type C MCB can be used for the motoring circuits. B type MCB's are recommended for lamps, fans, ovens, washing machines, house wiring etc C type MCB's are recommended for Air conditioners, transformers and industrial loads. —Preceding unsigned comment added by 59.180.45.131 (talk) 06:46, 8 June 2008 (UTC)

further to above....how do i know which MCB to be used...6A or 10A or 16A or 20A....for domestic lighting purposes. —Preceding unsigned comment added by 59.178.156.253 (talk) 06:47, 4 July 2009 (UTC)

Standars Values
It should be noted that the listed standard low voltage molded case braker values are British or European sizes based on European standards and 240v system. The US sstandard values are different. —Preceding unsigned comment added by Mattmia2 (talk • contribs) 13:12, 20 September 2007 (UTC)

Speed up Arc Extinction
There are various types of high current, high voltage circuit breakers used by Power Industries, such as Air Blast, Minimum Oil, Vacuum, SF6 gas filled, Magnetic arc-quenched varieties etc. Apart from making or breaking the current flows in Power Lines, their main functions are to extinguish electric arcs that follow a circuit-current break. In an arc channel between two parting contacts one may delineate three distinct regions, viz, two thin regions attached to the parting electrodes and a central column. The thin regions act as interfaces conjoining the high density and low velocity e-flow within the electrodes and the low density and high velocity e-flow in the usually long central column. Such interfaces at anode are rather diffused and current densities are relatively low whereas at cathode end they are focused and current densities are high. The Electrical parameters on either side of this interface are widely separated and the mechanisms operative here are very complex. Only at low pressures, the interfaces at cathode end are spread out and some theoretical analyses as well as diagnostics of the arc parameters have been attempted.

All circuit breakers in general, are designed to extinguish the arcs by drawing out their central columns using an air blast, a gushing oil stream or a pinching magnetic field etc guided more by mechanical constructional conveniences. But, in general, an arc is relatively ‘strong’ and ‘stable’ at the mid-column regions and rather weak at the electrode interfaces, particularly at Cathode surface. Attempts to extinguish arcs at such weakest points should be beneficial as regards total energy dissipation and delay to extinction and hardly any report on such efforts is available. Initial experiments to verify the concepts may be pursued with only simple, plane parallel, stationary electrodes. Would any users be interested to participate in developing the theories / devising the experiments in this direction? We shall develop a model of the processes active in the cathode interface of the arcs shortly. —Preceding unsigned comment added by 210.211.202.164 (talk) 08:23, 25 October 2007 (UTC)

duplication of text
In the headlines "Rated current" and "Short circuit current". —Preceding unsigned comment added by Yossso (talk • contribs) 23:10, 20 August 2008 (UTC)

reasons for complexity of high voltage circuit breakers
The amount of content in the high voltage section suggests that stopping the current from flowing is not trivial. Perhaps this should be stated explicitly. Reading the article I infer that arcing is a normal occurence when trying to stop the current flow, and requires special measures to stop it (stop it safely?). I am no expert on the subject so I'm hesitant to edit. Walworth (talk) 11:40, 21 January 2009 (UTC)

More basic information needed by prospective users.
The reason most prospective users are interested in looking up circuit breakers, is for help in choosing an appropriate type. Of paramount importance is how the breaker attaches to the buss bar. The amount of space allotted to extraneous technical details crowds pertinent information off the page. As a user who has experienced breaker failure due to poor engineering I am in interested in basic construction. How about someone who has the needed information creating a simple page which contains information that is needed by the prospective customer. Pictures of the lever arrangement for opening and closing the circuit are fine, but one is enough since "if you've seen one you've seen 'em all" but the attachment arrangements of hooks and catches, of which there is great diversity, are considered unimportant by the average technical writer. On Wikipedia the more things change the more they stay the same. How about some basic circuit breaker information and limit the technical verbosity on at least one page. Please.24.145.62.13 (talk) 23:30, 28 October 2009 (UTC)
 * But an encyclopedia is not a catalog. Choosing the appropriate type of circuit breaker for a given application requires more expertise than can be reasonably put into an encyclopedia article. It is appropriate to talk about basic common principles here, not exhaustively list (as one of thousands of possible examples) which brands and models of miniature molded-case circuit breakers fit which brands and models of panel boards without violating UL approval. Which circuit breakers would you have us describe here - the 3 Amp one that protects a TV set, or the one that failed and blacked out an entire 230,000 kV service for a large city? You could easily fill a Wikipedia with circuit breaker descriptions, application guides, and outline drawings - but this is the job of the manufacturers, not of an encyclopedia. --Wtshymanski (talk) 20:05, 13 November 2009 (UTC)

 * User:okeos

The 400 KV image does not show any breaker or switchgeer. It shows a small part of the 'visual indidicator of an open circut' which sits on both sides of a breaker. When a breaker opens then on both sides rods open to provide a visual indication that the circuit is not currently engaged. The Circut breaker for a 400KV line is much larger. —Preceding unsigned comment added by 68.144.56.118 (talk) 11:09, 7 March 2010 (UTC)

I came to article looking for information about response time of household AC panel circuit breakers -- the 15A - 100A types one would find in entrance panel. Found nothing. Also interested in response time of small resettable breakers attached to power strips, UPS's, various appliances (these range from 3-15A generally). None of article's external links gave any of this info either. Some mention would be useful, as well as one sentence indicating that because of this delay (xx-xxx millisec.?) that GFCI protection devices would be needed to protect users of equipment. I don't recall if article presently states that circuit breaker's main role is to protect circuitry and equipment, NOT users! But it should. —Preceding unsigned comment added by PapaJupe (talk • contribs) 16:10, 2 April 2010 (UTC)

I am new to wiki so if I violate any guidelines, please delete There are so many manufactures styles and vintages that images and specs would take thousands of pages If specs, size AIC ratings or pictures of cicuit breakers are needed, I will be happy to furnish them. — Preceding unsigned comment added by Circuit breakers (talk • contribs) 19:22, 6 December 2016 (UTC)

Medium-voltage circuit breakers ... are often built with draw-out construction
When they can be fixed needs clarification. This seems to indicate drawout construction is really optional. —Preceding unsigned comment added by 99.146.242.51 (talk) 18:02, 29 May 2010 (UTC)

Instantaneous tripping current terminology / formula
OK, am I just not getting something fundamental here, is it an esoteric sort of equation which needs further inline (or linked) explanation for a layman (i.e. the everyday wiki searcher) to understand, or it it an outright mistake?

The rating is described as being of the form "x/n", where x is determined by the rating (e.g. 2~3 for "B"), and, I can only assume, n is the breaker's normal rated current (ie long term sustained current).

Now what this means is, if I understand how this is written, for and within each of the classes - B, C, D, etc - the higher the sustained current rating, the lower the instantaneous tripping current, in a classical inverse relationship. E.G. for a B-class breaker, rated at 6A continuous, the ITC is between 0.333 and 0.5A (2-3/6, or 1/3-1/2). But one rated at 20A continuous has an ITC of only 0.1 to 0.15A (2/20-3/20...)

This surely can't be correct. So where's the misunderstanding/mistake? 193.63.174.10 (talk) 11:44, 30 September 2010 (UTC)

Hydraulic-magnetic circuit breaker
I think the following topic is missing in the article:

Hydraulic magnetic circuit breakers incorporate an hydraulic machanism for overload protection. This usually substitutes the thermal part of magneto-thermic breakers. Basically, the magnetic coil tries to pull a ferromagnetic rod which is confined in a liquid medium. A spring tries to keep the rod at the rest position. Depending on the overload, this rod moves faster or slower towards the tripping end. At the time it reaches the tripping end, the breaker opens the circuit. Different curves are possible by adjusting the liquid flow by means of a small hole of calibrated diameter. Therefore, the pair coil-spring (force and counter-force) adjusts the steady current capacity, and the pair liquid-hole (drag force) adjust the tripping curve. Hydraulic magnetic switches are preferred to magneto-thermic ones in that the operation does not depend on the temperature, and therefore these dispositives are able to be rearmed immediately after a trip and function as the first time. In other words, they have no memory effect.

Google returns several links under "hydraulic magnetic". Here is one:

Thanks. —Preceding unsigned comment added by Jsola (talk • contribs) 07:56, 6 May 2011 (UTC)

 * Hydraulic-magnetic breakers do indeed exist. The were and still are still manufactured in the UK by a company called Crabtree.  Their most popular model being the C50, available in both single and three phase versions, though they are quite large compared to modern designs.

 * Your description of operation is not quite correct (but close). The mechanism consists of an oil filled dashpot with a ferrous core spring loaded to one end.  On moderate overload, the current draws the core along the dashpot against the spring.  As the core moves, the magnetic field concentrated at the other end increases until it is strong enough to trip the breaker.  As the overload increases, the speed of movement through the dashpot increases, but the core does not need to move as far.  Near instantaneous operation occurs if the overload is large enough that the magnetic field is able to trip the breaker before the core starts to move.  The exact design of the dashpot and core determines the breaker's characteristics (the assembly being common among like type breakers), with the energising coil determining the current rating.  Unlike thermal breakers, hydraulic-magnetic breakers have to be designed for AC circuits or for DC because their characteristics are markedly different on such circuits.  Contrast a thermal breaker which van be used on either circuit provided its contacts are DC rated.

 * You are incorrect to assert that the operation is independent of temperature. The viscosity of the oil in the dashpot is very temperature dependent and the time -v- current characteristic shortens as temperature rises more rapidly than the equivalent characteristic of a thermal breaker.

 * You are correct (if I read your English correctly) that a Hydraulic magnetic breaker fully resets very quickly once it has tripped as the spring restores the ferrous core to the end of the dashpot almost immediately. Contrast a thermal breaker where the heated parts takes a significant time to cool down.  Unfortunately, I cannot locate any material on the operation so cannot cite an addition to the article. HasAnyoneSeenMyMarbles (talk) 14:57, 8 February 2017 (UTC)
 * At least the type is mentioned now. The lack of discussion of this type in my local standard electrical references comforts me that this was not a major oversight in the article as it stood, though. --Wtshymanski (talk) 20:36, 9 February 2017 (UTC)

US 15A/20A most common breakers
Please add a sample picture of the most common 15A/20A US circuit breakers. Please add the fact that 15A and 20A are the most common sizes of residential circuit breakers in the US. -96.233.19.191 (talk) 14:50, 11 July 2014 (UTC)

trip speed
The "Instantaneous tripping current" section is too theoretical.

We need a graph illustration like this one:
 * www.bluesea.com/support/articles/Circuit_Protection/100/Fuse_Circuit_Breaker_Speed_Explained
 * Speed Delay
 * Opening speed, or delay, defines the relationship between the percentage by which the fuse or circuit breaker is operating over its Amperage Rating and the length of time that will be required for it to open. The opening of a fuse or circuit breaker is determined not just by the amperage rating, but by the amount of time and the percentage over its amperage rating at which it is being operated. The higher the % of current flow to amperage rating, the faster the circuit protector will open.
 * A chart such as the one shown here commonly represents this relationship.

and text that both explains the general concept and gives a maximally relevant ordinary-case example. So if this graph did apply to a common US 20A circuit breaker, we would say that the breaker would be expected to pass up to at least 22A on a continuous basis, and would pass a surge of at least 60A for a tenth of a second without tripping, but could be expected to trip within 1-sec max at 40A. At 25A it might trip as quickly as half a sec, but might take up to about a half min.

And we should specifically mention "nuisance tripping", and explain that motors have short-term peak surge currents when they start, so circuit breakers are designed to not trip too quickly. -96.233.19.191 (talk) 16:39, 11 July 2014 (UTC)

Lever positions - Article states "Also indicates the status of the circuit breaker (On or Off/tripped)." We should edit the parenthetical remarks to say (On, tripped, Off, Reset). If no one objects here, I shall return and make the correction. Sponsion (talk) 20:14, 20 January 2017 (UTC)

UL standards (USA) are confusing and lacking (with broken refs)
I wish the USA's standards were described as well as internation ones. From the article: "In the United States, Underwriters Laboratories (UL) certifies equipment ratings, called Series Ratings (or “integrated equipment ratings”), using a two-tier rating. For example, a 22/10 rating. This rating means that the meter pack has a 22 kAIC tenant breaker, feeding a 10 kAIC loadcenter with 10 kAIC branches, where kAIC stands for “Thousand Ampere Interrupting Capacity.” Common meter pack ratings are 22/10, 42/10 and 100/10."

As a engineer with a masters (not to boast, just for context), I can't understand this jargon at all. The reference, is broken with no Google cache. What's a tenant breaker? What's a loadcenter? — Preceding unsigned comment added by 169.231.82.57 (talk) 22:15, 18 February 2013 (UTC)

UL listing means the original equipment manufacturer (OEM) prepares a white paper about their product and states emphatically the stringent safety test(s) the OEM will perform during manufacture of their product. UL regularly visits the OEM and certifies the OEM is testing their product based upon the OEMs stated safety test(s). Sponsion (talk) 19:52, 20 January 2017 (UTC)

breakers
how often do circuit breakers go bad themselves? Jeff Kizziar 01/03/15--71.32.95.26 (talk) 21:30, 3 January 2015 (UTC)

miniature history
why we cal circut breaker miniature?????Mohammadsdtmnd (talk) 12:58, 26 October 2015 (UTC)

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Electrical Fire Risks Associated with Circuit Breakers
An analysis of the fire risks associated with circuit breakers? One imagines that, certainly with high voltage applications, there is the potential for fires to start when the contact arcs of the circuit breaker damage the material out of which the circuit breaker is made. Are circuit breakers lined with/made from flame re-tardant/flame proof materials? Sorry if this is a silly question, but the article doesn't seem to mention the word 'fire' at all. ASavantDude (talk) 16:07, 10 March 2017 (UTC)

Carbon dioxide (CO2) high-voltage
"By switching from SF6 to CO2 it is possible to reduce the CO2 emissions by 10 tons during the product's life cycle." This is a faithful reproduction of the source but I think it is misleading. It probably means "greenhouse gas equivalent to 10 tons of CO2". Comments please. Mock wurzel soup (talk) 00:31, 14 September 2019 (UTC)

Why 63, 630, 6300?
What is the history of 63A rated circuit breakers? It seems like an odd number. — Preceding unsigned comment added by 124.187.243.156 (talk) 02:57, 11 February 2022 (UTC)
 * It depends on which series of preferred numbers your standards agencies like to use. IEC standards like to space out ratings a little more evenly in a decade than the 1-2-5 sequence. This is why we have NEMA standard circuit breakers rated 50, 60, 70,, etc. amps. --Wtshymanski (talk) 16:31, 1 July 2024 (UTC)

 * Here in the UK, a 63 amp circuit breaker is a standard size. While most circuit breakers are the more usually encountered sizes, there are a few that were intended for ring circuit systems. 32 amp for single phase ring circuits using 13 amp sockets (limited only by area covered), and 63 amp for 32 amp sockets in either a single or three phase system (also limited by area covered). We also have a 16 amp breaker solely for single phase radial circuits using not more than 8 x 13 amp sockets (a double counts as 2). We can also have a 9 to 12 x 13 amp socket single phase radial circuit, but that uses a more standard size 20 amp breaker.

 * AFAIAA, there is no 630 amp or 6300 amp breaker. 2A00:23C8:9883:A001:9C13:B6AB:B05:437C (talk) 12:36, 2 July 2024 (UTC)
 * You'd probably only find a 630 amp frame size circuit breaker in a list of IEC-rated equipment. 6300 amp would be a very large circuit breaker, the only ones I can think of that would be in that capacity range ( or greater) would be generator circuit breakers and their ratings don't seem to follow the preferred number sequence because they are so specialized. --Wtshymanski (talk) 20:26, 4 July 2024 (UTC)

Typo found
The link to [magnetic blowout coils] about 3 pages into circuit breaker article mis-directs to something else (contactors). Tim Coahran (talk) 21:04, 25 June 2023 (UTC)

Later: disregard. I found it when following the link to the full article, rather than just viewing the thumbnail.

"Vacuum circuit breaker" listed at Redirects for discussion
The redirect [//en.wikipedia.org/w/index.php?title=Vacuum_circuit_breaker&redirect=no Vacuum circuit breaker] has been listed at redirects for discussion to determine whether its use and function meets the redirect guidelines. Readers of this page are welcome to comment on this redirect at  until a consensus is reached. Couruu (talk) 12:57, 24 June 2024 (UTC)

title: Talk:Circuit breaker


text:
Hanlon Expressway

The Hanlon Expressway or Hanlon Parkway is a high-capacity at-grade suburban limited-access road connecting Highway 401 with the city of Guelph in the Canadian province of Ontario. The 17 km route travels in a generally north–south direction on the city's west side. It is signed as Highway 6 for its entire length; from Wellington Street to Woodlawn Road it is concurrent with Highway 7. The speed limit alternates between 70 and 80 km/h (45 and 50 mph).

The road was originally designed to be a freeway, but budget limitations precluded the construction of overpasses; apart from the interchanges with Highway 401, Laird Road, and Wellington Street West (Highway 7 and former Highway 24), all junctions are at-grade intersections. There are also two railway crossings near the northern terminus, though both are for spur lines. The Hanlon is graded and landscaped similarly to a freeway, with broad flat shoulders and an open median.

It was initially built between 1972 and 1975, after years of planning and engineering. The first interchange, at Wellington Street, was opened 25 years later in 2001. In late 2013, a second interchange was completed at Laird Road. The Government of Ontario has announced plans to build a new Highway 7 freeway bypass joining the current northern terminus of the Hanlon Expressway to the Conestoga Parkway in Kitchener; in-line with this work, the Hanlon Expressway will be upgraded to 400-series standards. Long-term plans call for a potential extension south of Highway 401 to meet Highway 6 south of Freelton.

Route description
The Hanlon Expressway begins at a trumpet interchange with Highway 401 and cuts through several farms northward before curving slightly westward to follow along the west side of the right-of-way of Hanlon Road. It enters Guelph at Maltby Road, skirting the outskirts of urban development. At the Laird Road interchange, opened in late 2013, the expressway encounters the Hanlon Creek Business Park. As it progresses into residential subdivisions, the Hanlon Expressway encounters an at-grade intersection, with Downey Road travelling to the west and Kortright Road West to the east. Continuing north, the route crosses to the east side of the Hanlon Road right-of-way as it intersects Stone Road West to the west of the Stone Road Mall. Before crossing the Speed River, the expressway meets College Avenue West, an at-grade intersection at the southwest corner of Centennial Park Arena.

The Hanlon Expressway crosses the Speed River as it swerves to the west and meets Wellington Street, the only other interchange along the route. To the east, Wellington Road is Highway 7, which follows the Hanlon Expressway north from the interchange; to the west it was formerly Highway 24. North of the Wellington Road the expressway was built slightly west of what is now Silvercreek Parkway. It passes beneath the a line of the Goderich–Exeter Railway, a sideline of the Canadian Pacific Railway, before encountering three at-grade intersections: Paisley Road, Willow Road and Speedvale Avenue West. This section also features two at-grade rail crossings. Shortly thereafter, it ends at Woodlawn Road West; Highway 6 travels east from this point while Highway 7 travels west.

The road, like with nearby Hanlon Creek, is named after Felix Hanlon, one of the men who cut the first tree in Guelph along with John Galt. He was one of the original settlers in the area, and his family eventually deeded their land to the city.

History
Prior to the construction of the Hanlon Expressway, Hanlon Road existed as far north as College Avenue. Edinburgh Road was the westernmost crossing of the Speed River. On the opposite side of the valley, Silvercreek Road continued, as it does today, along the same right-of-way as Hanlon Road. With the rapid suburban expansion of Guelph in the 1950s and 1960s, a revised transportation plan was conceived to handle the increasing traffic load. The Guelph Area Transportation Study was completed in 1967, and recommended a new controlled-access highway to allow through-traffic on Highway 6 to bypass the city. Route planning, engineering and design began on October 2, 1967 and was subsequently completed in 1969. Construction began between Waterloo Avenue and Stone Road in 1970; this section opened on June 28, 1972. The next section, from Stone Road to Clair Road, opened in October 1973. Work on the northern section from Waterloo Avenue to Woodlawn Road began in August 1974. That section, as well as the final section south to Highway 401 were opened on November 7, 1975.

Initially, the Hanlon featured no interchanges. Despite this, this Ministry of Transportation of Ontario (MTO) has planned to upgrade the route to a freeway since at least 1994, when an environmental assessment (EA) for the expressway north of the Speed River was completed. Construction of the Wellington Avenue interchange began in October 1998; it opened in July 2001, connecting Wellington Street west of the expressway with the Silvercreek Parkway into downtown Guelph. The interchange cost C$13.2 million and opened a year later than expected due to a design flaw that resulted in several months of delay and a lawsuit against the MTO resulting in a budget overrun of C$3.2 million. No further work has been done north of the Speed River, and the 1994 EA now requires updating. On April 30, 2012, construction began on the Laird Road interchange. It partially opened on the week of November 11, 2013, and was fully opened on November 29, 2013, in a public ceremony attended by local officials as well as Guelph MPP Liz Sandals.

Future
As initially envisioned, the Hanlon Expressway will be upgraded to a controlled-access highway by removing all existing at-grade intersections and improving the highway to 400-series standards. Planning for this work initially began in the early 1990s with the EA for the section north of the Speed River, which resulted in the construction of the Wellington Street interchange. The EA for the section south of the Speed River began in early 2007. The Laird Road interchange and associated closing of the Clair Road intersection were the first projects completed as part of this work.

Future projects will result in numerous changes. A full interchange will be constructed between Wellington County Road 34 and Maltby Road; the intersection with the former will become an overpass while the latter will be closed, with Maltby Road terminating at a cul-de-sac on both sides of the expressway. Further north, a partial-access diamond interchange will be built at Downey Road / Kortright Road West, with ramps from the northbound lanes and to the southbound lanes and the crossroad run beneath the expressway. The lack of ramps on the north side is due to the proximity of Stone Road to the north, where a full interchange will be constructed. A service road will be constructed along the west side of the expressway connecting Downey Road and Stone Road to provide better access to the YMCA, which previous controversial plans had neglected. At College Road, an underpass will be built.

license: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/4.0/

title: Hanlon Expressway


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Wikipedia:Articles for deletion/Center for computer research in music and accoustics

Center for computer research in music and accoustics was proposed for deletion. This page is an archive of the discussion about the proposed deletion. This page is no longer live. Further comments should be made on the article's talk page rather than here so that this page is preserved as an historic record. The result of the debate was DELETE

Because acoustics is spelt wrong in the page title, and it was only a redirect. I've moved its contents to the same title with the correct spelling. SimonW 19:22, 17 Dec 2004 (UTC)
 * Delete, though it should probably be on WP:RfD. --fvw *  23:37, 2004 Dec 17 (UTC)
 * Delete. No significant history, not a useful redirect, but yes, this should have been on redirects for deletion, not here, and was it always a redirect to CCRMA? If so it was pointless moving it, there was no history to save. No harm done! Andrewa 04:34, 18 Dec 2004 (UTC)
 * Speedy, SimonW both created this redirect and submitted it to vfd. Since no one else has touched it, it can be speedied. Wolfman 07:53, 18 Dec 2004 (UTC)

This page is now preserved as an archive of the debate and, like some other VfD subpages, is no longer 'live'. Subsequent comments on the issue, the deletion or on the decision-making process should be placed on the relevant 'live' pages. Please do not edit this page.


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File:Missing Persons - Spring Session M.jpg

Album cover for Spring Session M by Missing Persons

Fair use rationale for

 * It is believed that the use of this image on the English-language Wikipedia to illustrate an article on the audio recording in question falls under the "Non-profit educational" clause of the Fair Use doctrine currently upheld by United States law. (17 U.S.C. § 107)
 * The image is irreplaceable; a free analogue is impossible to produce as the original will be covered by copyright for the foreseeable future
 * Owing to the limited web-resolution of the image, only a small portion of a copyrighted work is used
 * For the same reasons, the portion of the copyrighted work used is of inherently lower quality than the original, reducing the risk of competitiveness and therefore the effects of this copy on the market for or value of versions held by the owner of the copyright


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Steve Sampson

Mark Stephen Sampson (born January 19, 1957) is an American soccer coach. He is also the former head coach of both the United States men's national team and the Los Angeles Galaxy of Major League Soccer.

Collegiate career
Sampson attended UCLA briefly before transferring to Foothill Community College, located in Los Altos Hills, California, in 1975. At Foothill Community he earned All-American honors while playing on the 1976 California junior college state championship team. He then transferred to San Jose State University in 1977. He graduated from San Jose State in 1979 with a minor in Spanish, which he later used as coach of the Costa Rica national team.

Beginning coaching
After graduating from San Jose State, he moved to Stanford University where he earned a master's degree in education from the Stanford Graduate School of Education. While at Stanford he entered the coaching ranks with the Awalt High School boys varsity soccer team in Mountain View, California. Then, after graduating from Stanford, he served as an assistant men's soccer coach at Foothill College. In 1982, UCLA hired Sampson as an assistant men's soccer coach. In 1985, he was on staff when UCLA won the NCAA men's soccer championship.

Santa Clara University
At the end of the 1985 season, Santa Clara University hired him away from UCLA to serve as their men's soccer head coach. In 1989, he achieved his greatest success as a college coach when he led Santa Clara to the NCAA Men's Soccer Championship. Santa Clara's opponent in the final was Virginia, coached by Bruce Arena, who would later succeed Sampson as head coach of the United States men's national soccer team. Santa Clara and Virginia played even through regular time and four overtimes before NCAA officials stopped the game, much to the frustration of the players and two coaches, and named Santa Clara and Virginia as co-champions. Sampson was named the 1989 NCAA Men's Soccer Coach of the Year. When he left Santa Clara, he had compiled a 64–19–19 record.

1994 World Cup
After leaving Santa Clara, Sampson became an assistant to Bora Milutinović on the United States national team in 1993 and was on the staff when the U.S. hosted the 1994 FIFA World Cup. In addition to his coaching duties, he served as the Vice President/Competition Management for the World Cup organization.

1995 Copa America
When Milutinović resigned from the team after the World Cup, the United States Soccer Federation (USSF) named Sampson as the interim coach in April 1995. After leading the US to a surprising fourth-place finish at the Copa América 1995, including a 3–0 romp over Argentina, as well as a victory over arch-rivals Mexico in the quarterfinals, Sampson was promoted to full-time national team coach in August 1995.

1998 Gold Cup
Sampson coached the team to a second-place finish in the 1998 Gold Cup, including a historic 1–0 victory over Brazil in the semi-final.

1998 World Cup
The US national team had a strong showing in the 1998 World Cup qualifying rounds, finishing with an 8–6–2 record overall.

Sampson attempted to improve the team by looking for Americans playing in Europe. David Regis was the most talented of those Sampson brought in but was impacted by delays in gaining his citizenship. Others like Michael Mason and David Wagner did not pan out as Sampson tried to overcome the weaknesses of a young MLS. In a controversial move, Sampson removed then captain, John Harkes from the squad. Sampson gave a variety of reasons, from Harkes' lack of leadership, Harkes wanting a more offensive role, and behavioral issues unbecoming of a national team player. There were injuries to both of the U.S.'s primary attacking threat, Eric Wynalda and creative midfielder Tab Ramos.

The 1998 World Cup would prove more challenging. Playing the likes of Germany and Yugoslavia were significantly more difficult than in CONCACAF qualifying. Sampson changed the formation in the spring of 1998 to an unusual 3–6–1 formation in preparation for the Germany match, trying to counter the quality of the German midfield. The conservative approach almost worked but was not to be as his team conceded a goal from a corner in the first half. When Sampson changed the system in the second half his team showed promise but was thwarted by an exceptional strike by Jürgen Klinsmann. The team lost 2–0. The second match against Iran showed a spirited team but one that could not find the back of the net. The U.S. team hit the crossbar and post on five occasions en route to a 2–1 loss in their most critical match. Counter-attack goals got the best of the U.S. seeking to overcome the Germany loss and the player unrest after that match. The lone goal came from Brian McBride. After significant personnel changes for the Yugoslavia game, the team lost 1–0. Failing to win a game and finishing in last place, Sampson resigned as coach on June 29, 1998. In February 2010, Sampson said that John Harkes was dropped from the 1998 World Cup because of an affair between Harkes and Amy Wynalda, then the wife of U.S. striker Eric Wynalda. Long rumored as the reason Harkes was dropped, Sampson finally cleared the air after Eric Wynalda confirmed the rumors during a discussion about the situation for the English National team in the run up to the 2010 World Cup in South Africa.

Costa Rica national team
In 2002, the Costa Rica national team hired Sampson as its head coach. In his first international post, he helped Costa Rica win the 2003 UNCAF Nations Cup, going undefeated. Costa Rica also finished fourth in the 2003 CONCACAF Gold Cup.

In 2004, Costa Rica ranked 17 in the world, their highest ever at the time. However, after Costa Rica needed the away goals tiebreaker to get past Cuba in the second round of qualifying for the 2006 World Cup, Sampson was fired.

Los Angeles Galaxy
Sampson was hired as the LA Galaxy coach on August 18, 2004, replacing Sigi Schmid. Despite an array of talent, the team was inconsistent the rest of the year and struggled for large stretches of 2005. Many of the players whom Sampson had brought into the team were absent from the Galaxy squad due to national team commitments for the US, Costa Rica, and Guatemala. As the season continued the Galaxy improved and eventually won the "double" of the U.S. Open Cup and MLS Cup, the latter as the lowest seed in the playoffs. The Galaxy failed to build on their success in the 2005 season and Sampson was fired on June 6, 2006, after Alexi Lalas, who played for Sampson on the US National Team, was hired as president.

Cal Poly
Steve Sampson was hired as the head men's soccer coach at California Polytechnic State University on December 4, 2014.

title: Steve Sampson


text: User talk:80.78.69.47

title: User talk:80.78.69.47


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Brilliant Pebbles

Brilliant Pebbles was a ballistic missile defense (BMD) system proposed by Lowell Wood and Edward Teller of the Lawrence Livermore National Laboratory (LLNL) in 1987, near the end of the Cold War. The system would consist of thousands of small satellites, each with missiles similar to conventional heat seeking missiles, placed in low Earth orbit constellations so that hundreds would be above the Soviet Union at all times. If the Soviets launched its ICBM fleet, the pebbles would detect their rocket motors using infrared seekers and collide with them. Because the pebble strikes the ICBM before the latter could release its warheads, each pebble could destroy several warheads with one shot.

The name is a play on the idea of Smart Rocks, a concept promoted by Daniel O. Graham as part of the Strategic Defense Initiative (SDI). This used large battle stations with powerful sensors, carrying dozens of small missiles, the rocks. To keep enough missiles above the Soviet Union at any given time, a minimum of 423 stations would be needed. The United States Air Force pointed out that this would require an enormous space lift capability, well beyond what was available. In meetings with Graham, Teller dismissed the concept as "outlandish" and vulnerable to attack by anti-satellite weapons. The SDI Office (SDIO) was similarly dismissive of the concept.

Teller and Wood initially proposed their own BMD system, Project Excalibur. This used an X-ray laser driven by a nuclear warhead that could attack dozens of ICBMs at once. In 1986, Excalibur failed several critical tests. Soon after, the American Physical Society published a report stating that none of the directed-energy weapons being studied by SDI were remotely ready for use. Abandoning these approaches for the short term, SDIO then promoted a new concept that was essentially a renamed Smart Rocks. It was at this point that Wood introduced Pebbles, suggesting that advances in sensors and microprocessors meant there was no need for a central station—the missiles could host all the equipment they needed to act alone. To attack this system, anti-satellite weapons would have to be launched against every pebble, not every station.

After considerable study, in 1990, Pebbles replaced Rocks as the baseline SDI design and in 1991 it was ordered into production and became the "crowning achievement of the Strategic Defense Initiative". By this time the Soviet Union was collapsing and the perceived threat changed to shorter-range theatre ballistic missiles. Pebbles was modified, but doing so raised its weight and cost; the original design called for around 10,000 missiles and would cost $10 to $20 billion, but by 1990 the cost for 4,600 had ballooned to $55 billion. Fighting in Congress through the early 1990s led to Pebbles' cancellation in 1993.

Smart Rocks

There are a wide variety of stories about the origins of Ronald Reagan's Strategic Defense Initiative. According to one often repeated tale, it was Reagan's viewing of Alfred Hitchcock's Torn Curtain that did it. Edward Teller instead pointed to a talk he gave on the topic of BMD in 1967 that Reagan attended. Others point to Reagan's visit to the Cheyenne Mountain Complex in 1979; there he saw the systems that could detect a Soviet launch and then track their warheads. When he asked what they could do in that situation, the answer was "launch our own missiles." Whatever the source, Reagan was convinced that Mutual Assured Destruction (MAD) was ridiculous, dismissing it as the international equivalent of a suicide pact.

Reagan asked Daniel O. Graham, his military advisor during the 1980 presidential campaign and former director of the Defense Intelligence Agency, to look for possible solutions. At first, Graham proposed a system of crewed space fighters, but the idea was quickly dismissed. Next, he revived the 1960s Project BAMBI to be the basis of a new system he referred to as Smart Rocks. This concept used "battle stations" in low Earth orbit, each carrying several dozen small missiles similar to a conventional air-to-air missile. The platforms would carry advanced sensors to detect and track Soviet ICBMs as they launched, and then launch its missiles and guide them until the missile's own infrared sensors picked up the ICBM. As the ICBM rocket engine was extremely bright in infrared, even a very simple interceptor missile could successfully track them.

As the interceptors were relatively small and carried a limited amount of rocket fuel, they could only attack ICBMs within a limited range of the stations. This meant the stations had to be in low orbit, to keep them close to their targets. At these altitudes, the stations moved at speeds around 17000 mph compared to the surface of the Earth. At that rate, any given station would spend only a few minutes over the Soviet Union. To ensure there were enough stations in the right locations at any given time, hundreds of stations were needed. The Air Force noted that there was nowhere near enough launch capacity to build such a system, and even if it could be launched, maintaining it would cost at least $30 billion a year in 1963 dollars (equivalent to $ billion in ). Additionally, it was noted that there was no effective way to protect the stations against attacks by anti-satellite weapons (ASATs), and the Soviets could easily afford to launch one for each platform.

Although twenty years had elapsed since BAMBI had first been studied and the concept had been re-examined several times, no obvious solution to these problems had presented itself. The Smart Rocks proposal, now known officially as Global Ballistic Missile Defense, ignored all of these problems, presenting a bare minimum of information. One observer derided the concept as being "one view-graph deep" and "unencumbered by practical engineering considerations or the laws of physics." In spite of this, Graham soon found a group of like-minded Republicans who formed a group known as the High Frontier Panel to help develop and support his idea. The group was led by Karl Bendetsen and began meeting in a room provided by The Heritage Foundation.

Excalibur

Around the same time that Graham was formulating his Smart Rocks concept, studies into X-ray lasers at Lawrence Livermore National Laboratory (LLNL or Livermore) made an apparent breakthrough. Nuclear explosions give off massive amounts of X-ray energy, and it appeared possible these could be focused down into narrow beams as the basis for a long-range laser weapon. Previous systems had used carbon-based lasing materials, but calculations showed that the energy could be greatly increased by using a metal rod instead. The idea had been largely theoretical until a key test of the new concept in November 1980.

By surrounding a nuclear warhead with dozens of rods, each could be independently aimed to shoot down an enemy missile. A single such warhead might be able to destroy 50 missiles in a radius of a 1000 km around it. A small fleet of such warheads could seriously disrupt any Soviet attack. In February 1981, Teller and Wood traveled to Washington to pitch the idea of a Manhattan Project-level development effort to produce these weapons in what they called Project Excalibur.

Teller was also a member of the High Frontier group and began attacking Graham's Smart Rocks as "outlandish", and suggested his own Excalibur be used in its place. Graham countered by pointing out a serious flaw in Excalibur; he noted that it worked by blowing itself up, so in the event a Soviet anti-satellite weapon approached, it could either blow itself up to attack the ASAT, or allow itself to be blown up by the ASAT. In either case, the Excalibur would be destroyed. Teller soon returned with a solution. In this concept, the Excalibur weapons would be placed on missiles on submarines and launched when needed.

Seeing himself increasingly sidelined, Graham left the group in December 1981 to form High Frontier Inc. In March 1982, they published a glossy book on the topic. It claimed that the system could be "fully deployed within five or six years at a minimum cost of some $10–$15 billion." A pre-publication copy was sent to the Air Force, who dismissed it, saying that it "had no technical merit and should be rejected."

Early failures, APS report

On 23 March 1983, Reagan gave his famous "Star Wars" speech that called on the scientists of the United States to build defenses that would render nuclear weapons obsolete. Over the next year this was formalized as the Strategic Defense Initiative Office (SDIO) as a separate branch under the Department of Defense, and soon, many of the United States weapons laboratories and major defense contractors were exploring a variety of systems to meet this goal. Along with Excalibur and the space-based laser, new proposals included ground-based lasers, various particle-beam weapons and nuclear shaped charges.

Through the early phases of SDI, the Smart Rocks concept was ignored by the SDIO. A study by research scientist Ashton Carter (to become Secretary of Defense much later) concluded that the system had "extremely limited capability for boost phase intercept of present Soviet ICBMs and no capability against future MX-like Soviet boosters, even with no Soviet effort to overcome the defense." Graham's connections in Washington's political circles meant the concept was well known in spite of any official indifference. This led to a constant stream of questions by politicians to the SDIO about the system and why they were not working on it. In 1985, Sam Nunn asked James A. Abrahamson, director of the SDIO, about it once again. Abrahamson stated that "he would not recommend that the United States proceed to deploy it."

By 1986, many of the systems being studied had run into difficulties. Among these was Teller's Excalibur, which failed several critical tests in 1986. A similar test carried out by skeptical physicists at Los Alamos National Laboratory suggested there was no lasing going on at all. Other concepts, like the neutral beam weapon which shot hydrogen atoms near the speed of light, demonstrated performance that was so poor it was unlikely it could ever work. The best among them all was the Space Based Laser, but it needed to improve its beam quality by at least 100 times before it would be able to disable an ICBM.

That same year, the American Physical Society (APS) published their review of the directed-energy weapon efforts. After a lengthy declassification procedure, it was released to the public in March 1987. Compiled by a veritable Who's Who in the laser and physics community, including a Nobel laureate Charles H. Townes, the lengthy report stated in no uncertain terms that none of the concepts were remotely ready for use. In every case, performance had to be improved at least a hundred times, and for some of the concepts, as much as a million times. It concluded that at least another decade of work was required before they would even know if any of the systems could ever reach the necessary performance.

Strategic Defense System
In a sudden reversal, in late 1986 Abrahamson and Secretary of Defense Caspar Weinberger agreed to proceed with a deployment option for a system that was for all intents and purposes an updated version of Smart Rocks. Named "Strategic Defense System, Phase I", or SDS for short, the concept added a ground-based interceptor that would be located in the United States, along with a host of radars and high- and low-orbit sensor satellites, all netted together with a command and control system. They briefed Reagan on the concept on 17 December 1986, and by mid-1987 had a proposal ready for review by the Defense Acquisition Board (DAB).

The system immediately faced withering criticism. As before, the newly christened "garage satellites" would be open to attack by anti-satellite weapons; a single ASAT attacking the station or its sensors could disable all of the interceptor missiles within. Although this concern had been raised before, the proponents still had no answer to this problem. But now the system added more critical elements, especially the high-orbit sensor satellites which not only had to survive, but had to be able to transmit their information at high speed to the interceptors. Disrupting any one of these many systems could render the system useless.

The $40 billion (equivalent to $ billion in ) budget estimate was dismissed as "pure fantasy". Over the next year the budget continued to grow, apparently without bound, first to $60 billion (equivalent to $ billion in ), to $75 billion (equivalent to $ billion in ), and then reaching $100 billion by April 1988 (equivalent to $ billion in ).

Brilliant Pebbles
After Excalibur's failed tests in 1986, the program was about to be defunded. At that time, Livermore had no other major SDI programs. Teller and Wood were looking for a concept that would be feasible.

The two had breakfast with Gregory Canavan, a Los Alamos physicist who worked on SDI related topics. Canavan noted that ongoing improvements meant microprocessors were on the verge of delivering supercomputer performance on a single chip. These chips were powerful enough that the processing capacity that formerly required the battle stations, or even computers on the ground, could now fit in the missiles themselves. Additionally, new sensors offered the optical resolution needed to track a missile at long range and still fit within a missile nose cone. Such a design offered an enormous advantage over the SDS; by flying freely, without a garage satellite, the interceptors could not be attacked en masse. If the Soviets wished to attack the system, they would have to launch an anti-satellite weapon for every one.

Wood began exploring the idea using back-of-the-envelope calculations. Wood's "O-group" had been working for some time on new computing systems in their S-1 project that aimed to produce a "supercomputer on a wafer". He combined this with a new sensor system known as "Popeye". At the speeds the interceptors and ICBMs would be approaching each other, the mass of the projectile had six times the energy of an equal weight of TNT, meaning no warhead would be needed. Considering how small such a system could be scaled, he came up with a lower limit under 1 g. But if one considered armored ICBMs, a practical lower limit would be a burnout weight around 1.5 to(-), in order to have more than enough impact energy to destroy any conceivable fuselage.

Considering the numbers required, it appeared a fleet would have on the order of 7,000 missiles in orbit, which would keep about 700 over the Soviet Union at any given time. The ratio of the total number of missiles in orbit to those available for action was known as the absentee ratio. If one wanted complete coverage against any potential attack, the numbers could reach as high as 100,000 missiles in total. Since the cost of each missile was expected to scale down into the $100,000 range, even the fully expanded system would cost $10 billion.

Launch costs were not part of that estimate. If the empty weight was on the order of a few kilograms, then a single Space Shuttle could launch dozens, perhaps hundreds. They were so light that some consideration was given to launching them from the ground using a railgun. Such lightweight designs would have a limited "cone of action", carrying so little rocket propellant that they could only attack targets right in front of them. A larger interceptor with more propellant could attack more targets, so smaller numbers would be needed to provide coverage. In any event, launch costs would be greatly reduced compared to the baseline system that required hundreds of battle stations, each of which weighed 30 ST and could only be launched one at a time.

Starting the next year, Wood had the former Excalibur team begin a more detailed study. By the fall of 1987, he had blueprints of the proposed design, a physical model to show, and computer simulations of the system in action. He also came up with a clever play on the Smart Rocks name, calling the newer, smaller, smarter concept Brilliant Pebbles. In another clever turn of phrase, one skeptical congressman would later refer to them as "loose marbles".

Pebbles becomes the Strategic Defense System

With Teller's help, Wood was able to brief Abrahamson on the concept in October 1987. Abrahamson was impressed enough to visit Livermore to view the mockups and watch the animated simulation they had created. This led to increased funding for further studies of the concept. In March 1988, Teller and Wood were able to directly brief President Reagan on the concept, taking the model pebble with them and theatrically hiding it under a black cloth when reporters were allowed to take pictures. Teller reiterated that the price for the system would be on the order of $10 billion.

In May 1988, Abrahamson initiated the Space Based Element Study in order to refine the design of SDS's Space Based Interceptor (SBI). As part of this study, he had Livermore's work considered as one of the interceptor concepts. This study agreed with the basic concept that all the required sensors could be placed on the missile. While this was going on, the United States Air Force Space Division began a similar study on the baseline Space Based Interceptor. They also concluded that the sensors could be on the missiles, greatly simplifying the stations.

For the next year, Wood and Teller ceaselessly advocated for Pebbles, to the point of it becoming something of a joke in Washington. During a briefing for reporters and congressional staff members, Charles Infosino, deputy director of the SDI architecture and analysis office, was quoted as saying "You may have seen Lowell Wood, who is responsible for this program, running around town with {a mockup}... on a little cart." There were concerns about the changing estimates through this period; cost estimates for the pebbles were initially $100,000, but by the end of 1988 this had already risen to $500,000 to $1.5 million. Additionally, the sensor alone cost several million dollars and there was scepticism about whether this could be scaled down by a factor of 10 as Wood's estimates required.

Moving towards production
George H. W. Bush became President in 1989, as the Cold War was coming to an end. He immediately ordered a review of all ongoing strategic programs. This led to the June 1989 National Security Directive 14, continuing the SDI program on the basis of the SDS. Meanwhile, Abrahamson's tenure at the helm of SDIO came to an end. He wrote an end-of-term report stating that Brilliant Pebbles should be aggressively pursued and that tests could be carried out within two years for a system deployment in five years at a total cost of $25 billion. Bush and Vice President Dan Quayle were vocal supporters of the Pebbles concept in the press; Quayle noted its low cost and light weight and stated that "it could revolutionize much of our thinking about strategic defense."

Abrahamson's replacement, George L. Monahan, Jr., planned a rapid series of studies with the goal of moving to approval for deployment by the end of the year. Among the first of these studies was one prepared by the JASONs, a standing committee of science advisers administered by Mitre Corporation. Their report essentially stated that there were no apparent "show stopper" issues in the concept, although they did have concerns about possible countermeasures. Soon after, a similar report by the Defense Science Board offered largely the same assessment.

A third review focussing on possible Soviet countermeasures did find that the system was possibly compromised by a number of issues, but pointed out that this was true for any other space-based system and these should not be the basis for selecting some other system over SDS. The final study, carried out late in 1989, was an Air Force report making one last comparison between the SDS concept with simplified "gun rack" garages versus a Pebbles system, which concluded the former would cost $69 billion and the latter $55 billion. This system included only 4,600 pebbles, and some of the savings were due to the removal of the high-orbit Boost Surveillance and Tracking System (BSTS), a role the pebbles themselves would fill.

Monahan had already given the DAB a "heads up" that major changes to the SDS concept were coming, and had been told to prepare a report for them for early 1990. The new system relied on Brilliant Pebbles as the baseline design. BSTS was not cancelled outright, but instead passed to the Air Force as a replacement for their existing Defense Support Program satellites. Other parts of the original design, including the land-based ERIS missile and its host of supporting radars and low-orbit satellites, remained.

Early contract tenders were sent to six suppliers for production vehicles. Testing was to run in a two-phase program, some of it in parallel. To start, LLNL would supply prototype pebbles interceptors that would be tested both on the ground and in space after launch on sounding rockets. This series would conclude in February 1993, in time to allow the President to review the system and decide whether to proceed. Information from these tests would be fed back into the production designs. The first of these prototypes would begin testing in June 1990 and end in June 1993.

Global Protection Against Limited Strikes

A month later, another independent review by Henry F. Cooper strongly supported Brilliant Pebbles over the alternatives. Cooper's report went much further. Considering the major changes to the strategic outlook with the ongoing dissolution of the Soviet Union, Cooper stated that the massive attack that SDS was designed to defeat was no longer the only concern, or even the main one. Instead, it was United States forces in the field that bore the brunt of the missile threat, this time from short and medium range missiles. Although the SDS system should move ahead, he suggested that the system be modified to provide defenses against these new threats.

Cooper noted that pebbles in their current form were designed to operate against a missile in the boost phase. Against a short-range rocket, this period would be too short for a pebble to reach it. To make it effective in this "Protection Against Limited missile Strikes" concept, or PALS, the pebbles should be able to continue tracking the missiles after their motors had burned out. This would either require a dramatic increase in the capability of the pebble's seekers, or require a network of low-orbit satellites to provide this same information.

Following Cooper's lead, Monahan began the Mid-and-Terminal Tiers Review (MATTR) in early 1990. Before this was complete, Cooper was appointed as the director of the SDIO on 10 July 1990, and Monahan retired. Within SDIO at least, PALS was now the mainline concept. In order to fill the need for a ground-based interceptor to back up the pebbles, the Army began development of the High Endoatmospheric Defense Interceptor (HEDI), essentially a short-range, mobile version of ERIS. A new lightweight interceptor, LEAP, would arm both ERIS and the Navy's Standard Missile.

As work continued, the Gulf War broke out and Cooper's scenario of United States troops being attacked by short range missiles came true; the nightly news carried vivid images of Scud missiles being attacked by Patriot missiles. Bush praised Patriot, claiming that 42 launches had resulted in 41 intercepts. Congress, formerly skeptical of SDI, suddenly had a very different opinion of the matter, especially with the realignment of the concept towards the PALS concept which would have been helping deal with missiles like Scud.

On 29 January 1991, Bush used the State of the Union speech to announce that SDI was being refocussed to the new "Global PALS", or GPALS, concept:

I have directed that the SDI program be refocused on providing protection from limited ballistic missile strikes – whatever their source. Let us pursue an SDI program that can deal with any future threat to the United States, to our forces overseas, and to our friends and allies.

This change in posture meant the system no longer had to deal with a large-scale attack, only small ones. Once again the number of pebbles was reduced, this time to between 750 and 1,000.

Missile Defense Act of 1991

The new GPALS concept was fully described in a May 1991 report published by the SDIO. It consisted of four parts: a ground-based missile system to protect the United States, a ground- and sea-based system to defend overseas United States forces and allies, Brilliant Pebbles in space, and a command and control system tying them all together. Brilliant Pebbles was seen as both a system for providing early detection of launches, as well as being able to attack any missile with a range greater than 600 km.

With the deployable system finally specified, the next step was to go to Congress for funding. This led to the Missile Defense Act of 1991. From one perspective, the Missile Defense Act was a victory for SDI as it considered making changes to the Anti-Ballistic Missile Treaty that would allow deployment, and ordered "robust funding" for Brilliant Pebbles. But it also stated that the immediate goal was to produce a Limited Defense System by 1996 what would be fully compliant with the Treaty, meaning it could have a maximum of 100 ground-based interceptors and they had to be in the vicinity of Grand Forks Air Force Base. It was specifically stated that Brilliant Pebbles would not be part of this initial system. Although there was some concern about the Missile Defense Act, many considered it to be the best deal that could be made.

Cooper essentially ignored the anti-Pebbles sentiment of the Missile Defense Act, and maintained its place as the primary weapon within the GPALS system. With funding secured, in June 1991 the SDIO sent out development contracts for Brilliant Pebbles and Brilliant Eyes to Martin Marietta and TRW. Brilliant Eyes was a low-orbit detection platform to aid Pebbles and the ground-based missiles. Additional contracts for the ground-based missiles and interceptors went out at the same time. This marked the first time since the Safeguard program of the 1960s that a production of a ballistic missile defense system was funded, and the first for SDI.

On 9 April 1992, Cooper testified before the Subcommittee on Strategic Forces of the Senate Armed Services Committee, where he was grilled by Democrats in the group. Sam Nunn, chairman of the Armed Services Committee, arrived late and then essentially took over the meeting. He noted that the complaints that SDIO was not being provided with the required funding was largely their problem, because Cooper was directing too much funding towards Pebbles, which would not be ready by 1996. He stated:

So, it is my assertion, Mr. Ambassador – which you can rebut – that what you’ve done by a combination of funding, and the reduction in GSTS, is, you made sure that Grand Forks would not be effective if we did it during this decade. Therefore, you made it almost impossible for it to happen during this decade. I don't know the motive for that, but that's what it looks like to me.

In defending his priorities, Cooper stated that the budget for these items was actually within the guidelines laid out the year before, about 11% for Pebbles and 14% for the other components of the space-based portion. He went on to suggest that the 1996 date was unrealistic and that setting priorities to make it happen would not help. Seeing the implied threat to the program, Cooper soon moved $2 billion out of Pebbles into the ground-based systems. Nunn reiterated his attack on Pebbles in August, at which point Secretary of Defense Dick Cheney stepped in and threatened that if the attacks continued that the president might veto the entire bill. His position was undermined by the failure of the third Pebbles test on 22 October 1992, when the booster broke up shortly after liftoff.

The final language for the 1992 version of the bill contained Nunn's language on the focus towards the Limited Defense System. It firmed up language that stated that the deployed system would have to be fully compliant with the ABM Treaty, and reduced funding for the space-based portions from $465 million in the 1991 version to $300 million. Further, the wording that the system should be deployed as rapidly as possible was dropped.

In November 1992, SDIO was forced to remove Pebbles from the deployment contracts, sending it back to a research program. On 18 December 1992, program management was transferred to the Air Force's Space and Missile Systems Center, and the January 1993 contracts were for "advanced technology demonstration" as opposed to a pre-production system.

Cancellation
Shortly after Bill Clinton became President in 1993, his new Secretary of Defense, Les Aspin, immediately began downgrading the Pebbles system. On 2 February 1993, he issued budget guidance lowering its budget from $100 million to $75 million, and moving it to the "follow on technology" category. In March 1993, it was renamed the Advanced Interceptor Technology Program.

On 1 May 1993, the SDIO became the Ballistic Missile Defense Organization (BMDO), reflecting the administration's shift towards the theatre ballistic missile problem. On 1 December 1993, James D. Carlson, its acting deputy director, ordered a stop work on the program. This was part of significant budget rollbacks to the entire program, limiting the organization to work on a single kill-vehicle. Brilliant Pebbles was dead. In August 1994, the Ballistic Missile Defense Organization was reoriented to a single Boost Phase Interceptor program.

Description

The final pebble design was similar to an air-to-air missile with no attempt at streamlining. The main body was about 3 feet long, most of that consisting of propellant tanks for the final-stage directional controls. At the very front was the LIDAR receiver, with the laser illuminator just behind it to one side along with the UV/visible light camera. At the rear were the batteries. Forward speed was provided by a series of four boosters known as "drop stages". Each consisted of a tank about the size of the pebble's own, along with a thruster engine at the rear.

For most of its lifetime, the pebble would be held inside its "life jacket". This provided electrical power via a solar panel, included a star tracker to provide basic alignment information, and carried a laser communications transceiver. The shell itself was intended to provide protection from laser strikes and pellets from the known Soviet anti-satellite weapon, part of the Istrebitel Sputnikov program.

Tests
Only three all-up tests of the Pebbles concept were carried out before the program was cancelled. All three failed for various reasons.

The first pebble test was carried out on 25 August 1990. This consisted of a basic airframe carrying an IR sensor, a star tracker and an attitude control system. It was to be launched to an altitude of 124 miles over Wallops Island, Virginia, by a Black Brant sounding rocket. After launch, the pebble was to separate from the rocket, and then use its sensors to keep itself oriented with the still firing third stage of the Brant while also recording its orientation through the star tracker. The stage would be above the horizon and would take place at night, easing the problem of tracking. One of the explosive bolts that was supposed to separate the rocket fired 81 seconds into flight, much earlier than planned, causing the fairing to flip over to one side and pull the pebble partially out of the airframe. The only success on the mission was that another experiment, the ultraviolet plume instrument (UVPI) flying in orbit above the launch, was able to successfully track the rocket. As a result of the failure of the first test, the follow-up series was delayed by 10 months.

The second test was carried out on 17 April 1991. In this case the interceptor was supposed to be looking down at the target against the daylight Earth, testing its capability to see targets in this orientation. Because of the failure of the first launch, it was decided to instead repeat the simpler nighttime test that was supposed to have occurred on the first flight. This test intended to have the interceptor separate from the launcher and then perform a programmed turn so it could see the launcher through several following test phases. The first phase was to simply acquire the target via its rocket plume and keep it in sight using the attitude control system. In the next phase, the interceptor would perform a series of more radical maneuvers in order to characterize the performance of the controls and the tracking system in a more realistic scenario. Finally, the system would perform another series of smaller maneuvers intended to be more accurate movements. This test was largely a failure; the system failed to pick up the target, and all of the subsequent movements were found to be much less accurate than required, to a large degree due to the failure of the gyroscopes. Some useful data characterizing the IR background was performed, but the UV sensor only recorded its own background noise.

The final test was carried out on 22 October 1992, using a much more developed prototype built by Livermore that had been miniaturized and was more indicative of a production model. This test would begin like the others, with both the kill vehicle and the target being launched from a single rocket at Wallops Island. Once the two vehicles separated, the kill vehicle was to begin tracking the target, and then use its propulsion system to bring it to within 10 m of the target vehicle. Seventeen seconds after liftoff the ground crew could see pieces falling off the booster, and it was destroyed by the range safety officer at 55 seconds. The problem was later traced to a failure in one of the rocket nozzles in the Aries I first stage.

Promising cost-exchange
Earlier anti-ballistic missile (ABM) systems like Nike Zeus had the problem that they cost more than the ICBMs they were designed to shoot down; the United States would have to purchase $20 worth of interceptors for every $1 the Soviets spent on new ICBMs. In such a situation, the Soviets could defeat any possible ABM deployment simply by building more missiles. This was a major argument against ABM systems in the 1960s and 70s, and became known as the cost-exchange ratio.

This led Paul Nitze to propose what became known as the Nitze criteria; to be successful, the marginal cost of adding to the defense had to be less than the cost of adding to the offense. If this is not true, then the simplest response to any new defense system is simply to build more offensive missiles. But if the defense is cheaper, this will not work, and the enemy will have to explore other solutions to address the imbalance. Ideally, they too would build defenses, ultimately rendering the offence impotent.

Compared to earlier ground-based systems, the Smart Rocks interceptor missiles were relatively simple and low-cost. This meant the US could afford to launch several for every Soviet ICBM. However, they suffered the major flaw that they were dependant on support from the garage, and thus a single anti-satellite weapon could render all of the interceptors inoperative. Smart Rocks thus failed the Nitze criterion, as it was less expensive for the Soviets to attack the system than it would be for the US to build it.

In contrast, the Pebbles interceptors flew independently, and thus to attack them the Soviets would have to launch an ASAT for each one. This would mean that developing countermeasures to the system would be on the same order of cost as the pebbles themselves, something the Soviets' weaker economy could not afford. This appeared to meet the Nitze criterion; they could not afford to build their way out of the problem either using ASATs or new ICBMs.

Absentee ratio
Critics noted a key flaw in this comparison; since it was only a pebble in the right place at the right time that could attack the ICBM, adding a single ICBM did not require one more pebble, but many more in order to fill out the orbit so one would be in the right area. In the case of Pebbles, this "absentee ratio" was on the order of 10-to-1, meaning that adding a single ICBM would require ten new pebbles, driving the cost much closer to parity.

As the Union of Concerned Scientists pointed out early in the SDI program, any system that relied on boost-phase attacks had to be able to reach the target while the missile's motor was still firing. With existing Soviet ICBMs like the SS-18, this period lasted as long as six minutes. The US's Minuteman missile fleet only burned for four minutes, and the new MX missile was even less. The report went on to explore the ultimate end of such a "fast burn" approach, concluding that it was possible to build a missile that would launch and disperse its warheads in as little as one minute. Such a missile would require many dozens of pebbles for each one so that at least one of them was close enough to catch it, making the defenses much more expensive than the ICBM.

The SDIO argued that such a response by the Soviets would be welcome; while the Soviets were deploying their fleet of new missiles to counter Pebbles, SDI would be on its way to deploying new systems based on directed energy weapons that could defeat those missiles. Critics noted that this meant the SDIO was arguing that Pebbles would lead to an offensive arms buildup, precisely the opposite of what they had previously claimed was the point of the entire SDI concept, and contrary to the Nitze criterion.

Other problems
Another issue raised was that the existing Soviet A-135 anti-ballistic missile system could be fired at the Pebbles. By timing such an attack moments before an ICBM launch, the A-135 system's 100 missiles could destroy those pebbles approaching the USSR and temporarily "punch a hole" for their ICBMs to fly through. Because of the absentee ratio, 1,000 additional pebbles would have to be added to the fleet to counter this possibility, not 100. This sort of attack would cost the Soviets very little.

Finally, there was another overarching technical issue that affected all of the space-based weapons. Since the late 1970s, the Soviets had used ground-based lasers to "paint" United States satellites on a number of occasions, in some cases temporarily blinding them. The APS report noted that the amount of energy needed to do this was very low, far less than the amount of energy needed to destroy a missile. This meant that while it was still unknown whether one could ever build a useful directed-energy anti-ICBM weapon, it was already possible to build an anti-SDI weapon that would blind such a system's sensors. One commentator went so far as to note that protecting the optics was "impossible". Such a system could be used against the pebbles in a fashion similar to the A-135, rendering them useless for a critical period while ICBMs were launched.

title: Brilliant Pebbles


text:
Rawene

Rawene is a town on the south side of the Hokianga harbour, in Northland, New Zealand. State Highway 12 passes to the south. The town lies at the apex of a peninsula. A car ferry links it to Kohukohu and the northern Hokianga.

History

Rawene started as a timber centre, with a mill and shipyards established in the early 19th century. An attempted settlement by the first New Zealand Company in 1826 failed. Captain James Herd in 1822 had taken out the first shipment of kauri from the Hokianga in his ship Providence. In 1825 he returned as an agent for the Company, sailing the Rosanna in company with the Lambton, and 60 settlers between the two vessels. Starting at Stewart Island/Rakiura, Herd sailed up the east coast eventually rounding North Cape to enter Hokianga - his old stamping ground. Herd negotiated to buy a vast tract of land. The deal was contested but for decades Europeans referred to the town as "Herd's Point". Later it was called "Hokianga Township", and in 1884 it became "Rawene", possibly to identify the post office and telegraph.

The post office had started operating by 1845 - one of eight in the country.

Aperahama Taonui, chief of Te Popoto hapū, allegedly operated a school at Rawene in the mid-19th century.

James Reddy Clendon, previously the United States Consul to New Zealand, settled in Rawene in 1862 and served as the local magistrate under the Native Circuit Courts Act until 1867. His house still stands and is open to the public.

By 1872 Rawene had two hotels and two stores. There was a Wesleyan church, and the Roman Catholics owned a section. Von Sturmer was the Postmaster, Customs Officer and Magistrate.

During the Dog Tax War of 1898 the residents of Rawene left for Kohukohu or took refuge on a steamer after the tax rebels threatened to march on the town. On 5 May 1898 120 men marched from Rawene to Waima to deal with the "rebels", but the dispute was settled without them.

A small cottage hospital was built on a hill overlooking the town in 1910. A new hospital was completed in 1928. Dr George McCall Smith headed the hospital from 1914 to 1948 and developed a unique health-system for the Hokianga.

Dr Smith became a practitioner of "painless childbirth" in the early 1930s, using premedication with the barbiturate Nembutal combined with Hyoscine. This proved very popular and attracted women to Rawene from far afield. The annual average of thirty births per year now peaked at two hundred. In 1937 a "Commission of Inquiry into Maternity Services" investigated Smith's practice. Smith fronted up with case notes on his last two hundred patients, and his results could not be bettered anywhere.

Parliament declared a special health area in the 1940s. This meant that all medical officers in the Hokianga were salaried, and all consultations, pharmaceuticals, investigations and hospital admissions were free. The whole scheme was funded through a per-capita grant.

Demographics
Statistics New Zealand describes Rawene as a rural settlement. It covers 2.15 km2 and had an estimated population of as of  with a population density of  people per km2. The settlement is part of the larger Hokianga South statistical area.

Rawene had a population of 498 at the 2018 New Zealand census, an increase of 27 people (5.7%) since the 2013 census, and an increase of 57 people (12.9%) since the 2006 census. There were 189 households, comprising 246 males and 246 females, giving a sex ratio of 1.0 males per female, with 96 people (19.3%) aged under 15 years, 63 (12.7%) aged 15 to 29, 201 (40.4%) aged 30 to 64, and 132 (26.5%) aged 65 or older.

Ethnicities were 54.8% European/Pākehā, 60.8% Māori, 8.4% Pacific peoples, 1.2% Asian, and 1.2% other ethnicities. People may identify with more than one ethnicity.

Although some people chose not to answer the census's question about religious affiliation, 47.6% had no religion, 39.2% were Christian, 4.2% had Māori religious beliefs, and 0.6% were Buddhist.

Of those at least 15 years old, 66 (16.4%) people had a bachelor's or higher degree, and 78 (19.4%) people had no formal qualifications. 27 people (6.7%) earned over $70,000 compared to 17.2% nationally. The employment status of those at least 15 was that 102 (25.4%) people were employed full-time, 63 (15.7%) were part-time, and 33 (8.2%) were unemployed.

Hokianga South statistical area
The statistical area of Hokianga South, which also includes Whirinaki, covers 126.04 km2 and had an estimated population of as of  with a population density of  people per km2.

Hokianga South had a population of 1,236 at the 2018 New Zealand census, a decrease of 3 people (−0.2%) since the 2013 census, and an increase of 171 people (16.1%) since the 2006 census. There were 444 households, comprising 612 males and 624 females, giving a sex ratio of 0.98 males per female. The median age was 46.2 years (compared with 37.4 years nationally), with 270 people (21.8%) aged under 15 years, 162 (13.1%) aged 15 to 29, 531 (43.0%) aged 30 to 64, and 273 (22.1%) aged 65 or older.

Ethnicities were 52.4% European/Pākehā, 63.1% Māori, 6.3% Pacific peoples, 1.5% Asian, and 1.5% other ethnicities. People may identify with more than one ethnicity.

The percentage of people born overseas was 10.4, compared with 27.1% nationally.

Although some people chose not to answer the census's question about religious affiliation, 42.7% had no religion, 41.5% were Christian, 6.3% had Māori religious beliefs, 0.2% were Muslim, 0.2% were Buddhist and 1.5% had other religions.

Of those at least 15 years old, 129 (13.4%) people had a bachelor's or higher degree, and 198 (20.5%) people had no formal qualifications. The median income was $18,700, compared with $31,800 nationally. 66 people (6.8%) earned over $70,000 compared to 17.2% nationally. The employment status of those at least 15 was that 288 (29.8%) people were employed full-time, 162 (16.8%) were part-time, and 66 (6.8%) were unemployed.

Education
Rawene School is a coeducational full primary (years 1-8) school has a roll of students as of

A room for secondary students was added to Rawene Primary School in 1922. In 1947 a stand-alone Rawene District High School was built. It was extended in 1952, but was destroyed by fire in 1972.

The Rawene Learning Centre is a campus of NorthTec polytechnic.

Notable people

 * Norm Maxwell, rugby union footballer and All Black.
 * Ron Guthrey, mayor of Christchurch (1968 to 1971).
 * Gordon Cochrane, WWII RNZAF bomber pilot.
 * René Shadbolt, nurse in Spanish Civil War, Hokianga hospital matron
 * George McCall Smith, doctor, medical superintendent, community leader

title: Rawene


text:
Mystery Spot

The Mystery Spot is a tourist attraction near Santa Cruz, California, opened in 1939 by George Prather. Visitors experience demonstrations that appear to defy gravity, on the short but steep uphill walk and inside a wooden building on the site. It is a popular tourist attraction, and gained recognition as a roadside "gravity box" or "tilted house". The site is what is known as a gravity hill and was the first of its kind to be built in California.

History
The Mystery Spot was opened by George Prather in 1939. Prather was an electrician, mechanic, and inventor who was born near Fresno and moved to Santa Cruz in 1920. He owned a welding shop and repair garage in the area before he opened the Mystery Spot. One of several roadside attractions that opened after World War II for new automobile owners, the Mystery Spot was featured on Art Baker's television show You Asked for It.

Prather was inspired to open the site by the popularity of the Oregon Vortex, which opened to the public in 1930. According to a newspaper report, Prather bought three acres on the hill in 1940 after he felt slightly dizzy while walking and was interested in his dizziness. The newspaper also reported that during further exploration of his property he found his compass jittering. He built a "crazy house" and opened the site to the public in June 1941. Tour guides lead visitors through the attraction and perform various demonstrations to showcase the site's unusual effects.

Prather died in January 1946; his son Bruce inherited the land and continued running the Mystery Spot with his father's business partner Vaden McCray. The McCray family was photographed for the Life magazine spread on the Mystery Spot for their November 15, 1948, issue. McCray died in 2001; Bruce Prather died in 2015. Christopher Smith now owns the property.

In July 2004, the Mystery Spot was nominated to be designated a California Historical Landmark, and received its designation (#1055) in August 2014.

Geography
The site is in Santa Cruz, California among the Santa Cruz mountains, Oak trees, Eucalyptus trees, near Granite Creek, and within the California Redwood forest. It is home to a man-made dahlia garden along the hiking trail.

Explanation
The Mystery Spot is a gravity hill, tilt-induced visual illusion. The illusion experienced by visitors results from the oddly tilted environment as well as standing on a tilted floor. Inside the tilted room, misperceptions of the height and orientation of objects occur. Even when people are standing outside on a level ground, the slant of the building in the background causes misperceptions as humans judge the height of people using the slant of the roof rather than the true horizon.

These visual illusions include balls rolling uphill and people leaning farther than normally possible without falling down. Psychologists at Berkeley state that all of the misperceptions stem from the simple fact that the house is slanted at a 20° angle. Professor William Prinzmetal states, "When the perceiver's body also is tilted, the distorting impact on vision is greatly magnified—up to two or three times." Another point he makes is that distorted orientation causes other senses to fall back while one's visual senses become heightened. People standing at impossible angles and water flowing uphill are related to the angle at which the house sits.

Other suggestions have been proposed to explain the reason behind The Mystery Spot's odd gravitational rules and illusions. Tour guides suggest that "a meteor which fell in ancient days and left a magic circle" is the cause behind the mystery, and suggest that an electromagnetic field on the hill deters wildlife. These theories are proposed for entertainment, not scientific reasoning.

Cultural relevance
The Mystery Spot was the first "gravity-defying" tourist attraction in California and was the most prominent illusion-based tourist attraction in California in the mid-20th century. It has been featured on BuzzFeed, and in the Santa Cruz Sentinel and other newspapers, comic strips, and travel blogs for decades.

title: Mystery Spot