RE: Question About Wiring Regs.

[Nigel Orr <nigel@xxxxxxx>]

At 09:19 01/11/00 +0000, you wrote:
>The IEEE have been a bit over-paranoid about wiring fires ever since
the
>70s when they got caught out by timber-framed houses.

Assuming you mean the IEE (the UK version), I'm not familiar with older
versions of the wiring regs (just the 15th and (current) 16th editions),
it's quite possible they had restrictions on proximity of other low voltage
cables for that reason.

It sounds a bit unlikely that it could happen- assuming something weedy
like phone cable, and assuming it would create a fire risk with 1A passing
along it, with a typical impedance of 600 ohms at the frequencies of
interest, it would need to induce a voltage of 600V in the cable.  That's
would take quite a bit of coiling of cables to achieve from a nearby 240V
line.

But the paranoia of bureaucrats should never be underestimated, I'm not
claiming it wasn't a concern at some time in the past, but I've not come
across it as an issue in audio, lighting, network or phone installation,
and I don't think there's mention of it in the current wiring
regs.  Anyway, as I've said, IME interference is an issue much earlier than
insulation for most cable runs (with the exception of signal and data
cables crossing mains cables at right angles), it's just the actual
interface equipment where insulation is a big issue.

Nigel


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