Talk:Domestic AC power plugs & sockets/M and D

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Type M and D do seem to have the same name and countries that use one do seem to use the other. M just seems to be the 15A version of D — I've seen both refered to as BS 546. Maybe they need amalgamating? Secretlondon 03:41, 6 Jul 2004 (UTC)

Yes, they look like the same thing to me, like the two Italian types. Dare we interfere with the letter system, though? If we do, we should probably abandon it completely.

Having said that... since M is at the end, it can be added to D without disrupting the order. — Chameleon My page/My talk 03:51, 6 Jul 2004 (UTC)

I have amalgamated them. — Chameleon My page/My talk 11:08, 10 Jul 2004 (UTC)

Type "D" is physically about half the size of type "M". They might both be defined in the same BS 546, but I don't think that's a good reason to amalgamate the two entries. It would be sensible to list them closer together, however. —AlanBarrett 08:05, 4 Aug 2004 (UTC)

I too would have preferred to move them closer, but that would interfere with the letter system too much, and I'm reluctant to do that. I put them both under D, but under different sub-sections. Do you know exactly how big they are? — Chameleon Main/Talk/Images 20:36, 5 Aug 2004 (UTC)

I can't find free on-line copies of the relevant BS or SABS standards. I did find this page at americor-usa.com which shows the dimensions of the type M plug. I don't have any type D plugs available to measure, but I'd estimate from memory that type D pin diameters and spacing are a little more than half that of the type M. A European 2-pin plug fits loosely into a type D socket, and usually wobbles around enough to cause arcing and poor contact. —AlanBarrett 15:59, 7 Aug 2004 (UTC)

Half? That would make them very small. — Chameleon Main/Talk/Images 21:17, 7 Aug 2004 (UTC)

I have an example of an M type plug and its matching socket, which has a machined groove around the base of the earth pin. The switch not only connects the mains, but also activates a mechanical interlock that engages with the groove, and retains the plug until the switch is unsert. I guess this is around 1950's vintage. Is this arrangement an option under the standard above, or a manufacturers own variant?

No idea. Take a photo of it and upload it! Where was it bought? What does it attach to? Chameleon 22:20, 12 Sep 2004 (UTC)

all the 15A plugs i have seen in the uk (i've been vaguely involved with theatre lighting) have just had solid round pins no grooves or anything. I would guess this was some manufacturers attempt at adding an extra safety feature that didn't catch on (plugwash)