Isolating electric circuits while working.

[Ivan Dobsky]

I've always switched off the whole lot at the consumer unit, but the bloke next door but one says he's happy to just pull out one of the fuses. I know what he's saying, and I understand why he's not killed himself yet, but I'm too much of a coward to do this myself. My feeling is, with the fuse pulled, the neutral is still connected, and if you're unlucky, something could happen outside of the property which might make it suddenly become live. Or am I being too cautious? It is sometimes a pain having to switch everything off, and if pulling the relevant fuse was sufficient, I'd rather do that.

[docholliday93]

How much do you trust the chap who installed the system? I've found quite a few cases where the fuse you need to pull isn't the one you'd expect (e.g. 13A sockets spurred off immersion heater wiring), so that's my main worry when jut pulling one fuse. I wouldn't expect the switch on the consumer unit to disconnect the neutral, anyway...

[Bob Eager]

The big double pole master switch on the consumer unit (to which the OP is undoubtedly referring) disconnects the neutral, by definition.

[Ivan Dobsky]

It seems mostly okay, but our downstairs lights are daisy-chained together, and a failure to properly connect an earth wire to one of the roses left two-thirds of them unearthed. This only came to light when I decided to try and find out why a metal-faced switch felt faintly tingly.

So, I can't trust him 100%

I'd have thought it was a double-pole switch, but I don't really know.

[Ivan Dobsky]

I've never really thought about it before, I just always assumed that was the case.

[Dave Plowman (News)]

I'm happy to work on something here by just switching off the relevant MCB, but I wired this place myself. I'd not do it without checking things elsewhere.

Trouble is if the circuit is also RCD protected. There's a good chance you'll trip that when working on things anyway.

[Ivan Dobsky]

No RCDs. But I'm not so much worried about the possibility of faulty wiring in the house. I'm just not entirely sure that there isn't something 'out there' (e.g. some fault or condition at the substation, or someone in the vicinity trying to bypass his electricity meter) that might make the neutral wire become unexpectedly dangerous.

[tony sayer]

In article , Ivan Dobsky scribeth thus

If its your house and you did the wring then go and pull the fuse.

Also short the live and neutral on the circuit your just about to work on it will go flash bang if its alive _but_ You stand a much better change of being alive afterwards;)..

If you pull just the fuse and other circuits are live and its RCD protected then a neutral earth short on the cables your working on will if any circuits elsewhere are pulling a bit of power will cause the RCB to trip.

Best bet is to switch it OFF at the main switch and pull the fuse/s on the circuit your working on and *** TAKE IT WITH *** you!.

I once had a real Wally put the bloody thing back whilst I was working on that circuit I almost thumped him one to try to knock some bloody sense into the prat after I got a severe belt !!!...

[tony sayer]

In article , Ivan Dobsky scribeth thus

Confucius he say .....

"Assumption was the mother of all f*ck up's";!)...

BTW where is olde a w_tom did he get struck down somewhere;?..

[Dave Plowman (News)]

Do you worry about getting hit by lightening too? ;-)

[Ivan Dobsky]

I know, I know :-) But some things are avoidable, and I have a family to think about.

[Ivan Dobsky]

I like that idea!

[Jethro_uk]

Sparky (older chap) who fitted some lights when we moved in put the fuse in his pocket. He said when he was an apprentice, his gaffer had removed a fuse in a warehouse they were working in, and placed it on top of the fusebox. Of course somebody wondered why the lights were off, investigated, replaced the fuse and the gaffer fell off a ladder to his death when he got a shock. Stories like that stick with you.

[charles]

we had a science teacher at school whose hair was completely white. A similar thing had happened to him, but he wasn't on a ladder.

[Mark Bluemel]

The rule when untangling carrier bags from the propeller of a canal boat is that the person doing it has the ignition key in their pocket...

[docholliday93]

OK, perhaps I should have said I wouldn't 100% trust it - having seen cases where it didn't - and one where it disconnected the neutral but not the live...

[cl]

**ALWAYS** check the circuit that you're working on is disconnected after pulling the fuse or switching the MCB. I usually use a lamp or a drill plugged into the circuit in question and do a check before (e.g. lamp on) and a check after (lamp off).

[charles]

when altering the lighting in this house, I found a junction box with red, black joined to black, red to leave.

[Dave Plowman (News)]

That checks the circuit is no longer made - but not that it's the line which is disconnected.

[whisky-dave]

I did a ceiling light for a friend, I switched off at the consumer unit. I thought bwell 15 mins job, I'll just leave everything off. Two hours later I finished.

Usually I switch off, remove the fuse on the circuit I'm working on, turn everythig back on and check with a neon screwdriver that I've pulled the right fuse.

Well I wouldn;t call it being a coward.

Think you're beingn slighly over cautious, nothing wrong with that unless you're being paid by the hour ;-) I tend to switch everything off (or as much as possible) before switching the CU off or back on, just to avoid surges while I'm close to the CU. :)