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.
I've certainly seen a lot of them, includign the higher-current ones. I
think my Zilog S8000 machine has such a mains connector.
I actually have a very nice book by Morgan Jones on
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
Actually that's true. The electrical safety rules came from the IEE
(Institute of Electrical Enginenrs, now renamed)
to that level of safety requirement here in the US for
equipment (and if we do, I don't think it's enforced often).
I beelive you can break the rules for prototypes,homebrew devices, etc.
Howev,er I try to avoid doing so (obviously there are times when
prototyping that yuou have live parts exposed, etc). I do amke sure
anything I build is properly earthed. 204V shocks are unpleasant if
you're lucky, if you are not lucky, you don't feel a thing -- ever again.
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
As I mentioned in anotehr message, I've seen that :-(
make them fit in 2-prong outlets. It's a typical
response to the square
peg/round hole problem: apply more force!
As an aside, the common mains plug/socket over hera has rectangualr pis,
specifically to make it incompatible with the earlier round pin ones.
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 only".
Yes. that type is allowed, in fact it;s the only type of socket allowed
in a bathroom (defined as a room containign a fixed bath or shower). The
reason is that the socket contains a double-wound isolating transformer
(abotu 20VA rating).
Some years ago one of the 'pounds shops' (equivalent of dollar stores)
over here had some of said sockets on sale (I guess they were bankrupt
stock or something). I bought all I could find. A 20VA mains isolating
transfomer (with the cecondary tapped at 115V, since said shaver sockets
often ahve a 115V outlet too) was well worth a pound ;-)
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
Tha'ts the main problem IMHO. Said adapters are only safe if the screw is
earthed (and if it is, why wasn't a 3 pin socket installed?). IF the
screw is earthe,d then of course the adapter is fine, it's equivalent,
really, to a 3 pin socket.
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).
Yes, they exist over here too. The circuit is beacially a delta of neone
and series resisotrs, often with a couple of otehr lad resisotrs so tht 2
neons in series will not strike. They indcate any signle wire being
disconencted, lvei/neutral swapped, etc.
They're not ahrd to get, and there have been projects to build then in
the magazinse over the years.
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.
Probably for the same reason that not everyone has a multimeter, a
solderign iron, etc :-).
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 built-in fuse is a nice feautr,e sure. It means that a failure of the
plugged-in device, even a dead short in the cable, notmally only blows
the fuse i nthe plug and you don't have to go to the consumer unit to
change the fuse.
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?
I wonder if that cable was actually intended for use in the UK, or in
whichever country it is that uses said socket son a radial circuit? I
would not be happy using it over here, unless plugged into a fused
mult-socket block (there is a common multiple socket over here, what you
cal la power strip, whth 4 13A sockets in parallel and a 13A fuse on the
incoming feed (which is generally connected to a 13A plug). You use them
to run several low-power devices from one wall socket, of course. In that
case, an unfused plug plugged into such a board is not a major safety
hazard, since the incoming feed is fused at 13A).