On Nov 27, 2011, at 3:09 PM, Tony Duell wrote:
"computer" power cords I have are rated at 10A, but they don't have the
notch down the middle, which would mean I'd have to modify one to plug
the thing in.
No, don;t do that. The 'Hot condition' connector is designed to withstand
the higher then normal temperatures produced by such devices, the ridge
is there ot prevend you from plugging a normal cable in. A normal cable
may well soften enough to be hazardous.
I wasn't seriously considering it; these protections are usually (though not always)
there for good reasons.
You can get 'hot codition' sockets quite
easily over here. I would be
suprised if Farnell didn't sell them (and thye have a US presense IIRC).
I think I've also seen that groove fitted to electronic equipment that requires a 15A
outlet, though it's really not the right plug. The Wikipedia article has nice
pictures of all the standard IEC end connectors, and I think I've seen all but one or
two of them in real use, which is surprising.
Over here, equipent must genrally either be
'double insulated' (which
means even in the event of a failure, exposed metal cannot become life)
or earthed. There is one exception to this -- a single-insulated
non-eartehd device that can still be legally sold -- christmas light
I actually have a very nice book by Morgan Jones on tube/valve amp construction which
details all of those requirements. It's the first exposure I ever had to UK grounding
requirements, and my first thought was, "Wow, I guess they had electrical engineers
come up with their electrical safety requirements". I don't think we have
anywhere close to that level of safety requirement here in the US for our electric
equipment (and if we do, I don't think it's enforced often).
I don;t know when they became common over here. The
older-style round pin
sockets existed in 2 and 3 pin versiosn (and were incompatible, in that
you couldn't plug the 2 plin plug into the 3 pin socket or vice versa).
All ring main socekts (the '13A' BS1362 one) are 3 pin, I think they were
introduced in 1948. I am also darn sure that fititng 2 pin non-earthed
sockets is against the regulations now (as it should be!).
I don't think fitting 2-prong outlets is allowed by building code here, either, though
I can't imagine why anyone would want to anyway. Our three-prong outlets are
backwards-compatible with the 2-prong plugs, which does lead to idiots prying off the
ground prong of many plugs to make them fit in 2-prong outlets. It's a typical
response to the square peg/round hole problem: apply more force!
I did see a two-prong outlet in a hostel bathroom in Edinburgh recently; no idea how
up-to-code that was, but it did have a prominent sign that said "for shavers
Yes, I've seen such adapters. I've also seen a
moulder US 115V plug wit
hthe earth pin cut off, presumably so it would go into a 2 pin socket.
The adaptors, when installed PROPERLY (which is a royal pain to do a lot of the time, as
the screw eye isn't always sized just right, and of course very few people actually
check with a meter to make sure the junction box is grounded) work more or less fine.
There are easily-obtained, cheap neon light devices over here (I'm sure they're
available everywhere else, too) which light up with different combinations for different
circuit faults (including proper wiring). They're the size of a stubby screwdriver,
cost a few dollars, and fit nicely in a toolbox; I don't understand why everyone
doesn't have one.
Ther'es one possible hazard over here. The normal
domestic power cirucit
is called a 'ring main'. As the name implies its a ring of cable and you
can fit as many 13A socket outlets onto it as you like (there are
restrictions as to the floor area it can cover, etc). The cable is rated
at 21A (IIRC) so the circuit can theoretically carry 42A (2 paralell
paths as it's a ring), it's fused at 30A in the 'consumer unit' (aka fuse
Anyway, since 30A is a ridiculaously high current
rating for portable
appliances, there's a cartridge fuse in the plug. These exist in a number
of current ratings, but only 3A and 13A are commonly used.
That's actually my favorite feature of UK power plugs (that and the fact that
they're occasionally larger than the equipment they power).
The worse hazard is that I have a mains lead which has
what appears to be
a UK 13A plug on one end (and will fit a normal UK mains socket) and an
IEC 320 connector on the other, but _no_ cartridge fuse in the moulded-on
plug. That is IMHO lethal over here. I believe it was made for use in
some other country which was once under British rule and which adopted
the same mains socket on a 15A radial circuit (one cable per socket
outlet, each socket indvidually fused in the consumer unit). In that
application you don't need the fuse in the plug.
I once received a PowerPC evaluation board which (surprisingly) came with an ATX power
supply with IEC cords for both the US and the UK. The cord didn't have a fuse, which
surprised me, but perhaps the kit was made up by someone unfamiliar with the regulations?