On 22/01/2009 18:50, Tony Duell wrote:
I beleive that Christmas lights are one of the few (if
not the only)
single-insulated non-earthed device that can be sold in the UK.
[ ... ]
I also wonder how the light bulb sockets (both the BC
(Baynoet Cap) ones
used in the UK and the ES ones used elsewhere are approved. With the bulb
removed (which can be done without the use of a tool), there are exposed
livel parts.
The IET Wiring Regulations merely require that you can't touch a live
part with a finger (and there's a standard to define how fat a finger
is) and without the use of a tool. It doesn't mean you can't remove the
bulb without a tool, it means you can't then touch the live part without
a tool. In the case of Christmas lights the metal is somewhat recessed,
and you can't get a finger in, so it's allowed. I assume here that
we're talking about the ones that use miniature E5 (5mm ES) bulbs. Of
course even in this case, you can touch the live part with a
screwdriver, the tines of a table fork, a paperclip, etc -- but those
are defined as tools :-) Amusingly, these lights are classed as if
double-insulated, even though all the ones I've seen are not -- the
rather bizarre justification for that definition seems to be simply that
they have no earth wire!
Can shops still sell such strings of lights? I've not seen any for
ages, only the spare bulbs, and ELV sets. The last time I saw any IET
publication about them was dated 2004 and I'm not sure if they are still
sold.
--
Pete Peter Turnbull
Network Manager
University of York