Electronic components sources

From: Tony Duell <ard_at_p850ug1.demon.co.uk>
Date: Tue Mar 23 18:02:22 2004

> If you break both, the device could float. Floating parts
> are generally not good in the electrical world, as their behavior is

Exactly why not?

Are you saying that the main switch in your fuse box / consumer unit /
breaker box / whatever you call the thing after the electricity meter in
your house is a single pole device ? In the UK it is _required_ to be a
double pole one, breaking live and neutral (and for 3 phase star
installations it's required to break all 3 phases and neutral).

> uncertain. It is always better to have a circuit whose behavior is known -
> even if the behavior involves fuses blowing for even silly little faults -

The behaviour of a circuit with a double pole mains switch is known. And
I have _never_ come across a problem that could only be explained by the
fact that both mains wires were disconnected.

> than to have one that could go anywhere.
>
> Floating circuits are also no fun for electricians. Many have been fooled
> (and zapped) when their wiggie lit (or did not light) because one end was
> connected to a flaoting wire.

The most common problem is that your neon tester will light on a
disconnected wire due to capacitive coupling to a still live wire. This
is a safe error, in that it says a wire is live when it's not. For the
life of me I don't see how a totally isolated circuit can test dead on a
neon tester but actually be live (in fact I don't see how it can be live
at all if it's isolated on both live and neutral wires).

>
> Wiggie: A small neon bulb tester, used by electricians to do quick and
> dirty checks for voltage.

Horrible things!.

-tony
Received on Tue Mar 23 2004 - 18:02:22 GMT