# Talk:AC power plugs and sockets

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AC power plugs and sockets is a former featured article. Please see the links under Article milestones below for its original nomination page (for older articles, check the nomination archive) and why it was removed.
This article appeared on Wikipedia's Main Page as Today's featured article on September 10, 2004.
Article milestones
DateProcessResult
July 21, 2004Featured article candidatePromoted
August 8, 2004Peer reviewReviewed
October 6, 2004Featured article reviewKept
October 23, 2006Featured article reviewDemoted
Current status: Former featured article

## broken URL

The URL http://www.iec.ch/worldplugs/list_bytype.htm gets a 404 error. Part of the problem is the fact that "worldplugs" should be "world-plugs". However, even when this is fixed, the error remains. -- RichMorin (talk) 23:19, 6 September 2021 (UTC)

Please somebody create a new article about child safety plugs, or whatever they are called.

Socket that looks like a face wearing glasses

Jidanni (talk) 18:07, 18 November 2021 (UTC)

They are described here: Childproofing#Electrical_safety. You can add a redirect. Gah4 (talk) 15:15, 6 December 2021 (UTC)

## Rating for Swiss plugs

The ratio between phase voltage (phase to neutral) and line voltage (phase to phase) is fixed. It cannot be any ratio other than the square root of three (1.732 to four significant figures). For a 250 volt phase voltage, the line voltage is 433 volts. For a 230 volt phase voltage, the line voltage is 398 volts. If a plug is rated at 250 volts phase voltage, then it must be rated at 440 volts for line voltage. If the plug is only rated at 400 volts line voltage, then application of the rated phase voltage will over stress the plug which is hazardous. Swiss documentation often refers to the three phase plugs and electrical system as being 250/400 volts. However, that documentation does not state that that is the rating for the plugs (or even the actual voltages) and therefore cannot be used to support any claim otherwise. The given voltages are merely their way of [incorrectly] stating the nominal voltages of the Swiss electrical system. The correct stated nominal voltages should be 230/400 volts but the plug's ratings should be 250/440 volts (ratings usually being rounded up to a standardised number). Even the Swiss "... canna change the laws of physics". 86.188.36.150 (talk) 18:12, 5 December 2021 (UTC)

As far as I know, no plug is anywhere close to dielectric breakdown. The ratings are all for political/legal purposes. This is especially true in Europe, where the voltage standardization tends to use 230V, when they mean somewhere between 220V and 240V. The answer to this question depends on Swiss law, not the laws of physics. Gah4 (talk) 21:50, 5 December 2021 (UTC)
Breakdown is often a long way from the specified working voltage and often the voltage at which plugs and sockets are tested. The US NEMA plugs (type A and B) are specified for 125 volts or thereabouts) but in practice they will usually operate without problem at 240 volts (and they often are on older installations in Thailand). Nevertheless, proper electrical practice dictates that a plug and socket should never be used at any voltage above its specified voltage (also true for current). If the Swiss three phase plug were really specified for a maximum of 400 volts line voltage, then such a plug would be marginally rated as the line voltage is less than two volts lower, which means that if the voltage deviates within its specified tolerance then the plug will become underrated. I know the Swiss well enough to know that they do not practise this sort of shoddy indulgence. The Swiss plug and socket designs are probably the best in the world and highly unlikely to be poorly rated.
Three phase (red) Commando plugs and sockets (to IEC/EN 60 309) are described as 400 volt plugs and sockets in most, if not all, catalogues. However, the specified line voltage for the plugs is 440 volts not 400 volts (though the test voltage is a lot higher). Just as well as they would otherwise be barred from use in the UK where the line voltage is 415 volts in most places and 433 in the suburbs of some cities (very notably London). Unfortunately: I cannot access the Swiss standard, but I would be very surprised indeed if it did not specify the line voltage for the three phase plugs as less than 440 volts as 440/250 volts seems to be standard for non North American plugs and sockets. 86.188.36.150 (talk) 11:26, 6 December 2021 (UTC)
Not being in Europe, I haven't followed it quite that close, but there is: Low Voltage Directive, otherwise called voltage harmonization, which is used to make things easier for all of Europe. As well as I know it, they use 230/400 with a large enough tolerance to cover the range from 220/380 to 240/416. In all cases, there is a tolerance on the voltage given. Voltages given are nominal voltages, not maximums, and this is all legal and not physics. Gah4 (talk) 15:12, 6 December 2021 (UTC)
The Low Voltage Directive does not apply to plugs and sockets because there is no unified design of plug and socket combination in Europe. As you say, there is the nominal voltage of the various electrical distribution systems. But it is not the plug (or socket) specified ratings just as in the example that I gave above. The so called voltage harmonisation was not a real harmonisation. All that happened is that Europe became nominally 230 volts plus or minus ten percent. The UK remained 240 volts (with pockets of resistance at 250 volts) and most of the rest of Europe remained at 220 volts. All encountered voltages are within the ten percent band which most modern appliances can tolerate without problems. The only exception is filament lamps which still remain available in some designs and these are still 240 volt in the UK and 220 volt in most of Europe. 86.188.36.150 (talk) 17:43, 6 December 2021 (UTC)
Yes. So a plug should be rated 230/400 which can be used +/- 10%. Plugs and outlets have a nominal voltage rating, not a maximum. Current ratings might be maximum, though still with a reasonable tolerance. Gah4 (talk) 19:24, 6 December 2021 (UTC)
No. The rating of a plug is the maximum voltage at which it should be used. This is why the IEC/EN 60 309 plugs are described as 400 volt plugs but are rated at 440 volts. If they were rated at 400 volts they could not legally be used in the UK.
I have discovered that the new SN 441011 specification revision due to become valid on 1st March 2022 specifies the phase to phase voltage rating for the type 15 and type 25 plugs and sockets as 440 volts (though it does describe them as 400 volt plugs). Since this new revision only changes certain aspects of checking the mechanical aspects of the pins of the plug, it can be safely assumed that the existing standard specifies 440 volts as the electrical characteristics are unaffected (I cannot access the current revision as money is required to change hands). 86.188.36.150 (talk) 13:39, 7 December 2021 (UTC)