Isolation Of First Floor Ring Main

[Max6979]

Does anyone know where I am going wrong? A friend wanted to know if a double socket which had been left with cables protruding ( wrapped with insulating tape ) by an electrician/ handyman was dead- I pulled the fuse labelled top floor ring main and I was told that top floor sockets were still live ( TV was still working in a bedrooom) .  I advised him therefore that socket still live and the only way to make certain it was dead was to turn off the main isolator switch to the CU. Is there any reason why pulling the fuse marked top floor ring main did not result in the top floor ring main sockets becoming dead ?

Sorry to ask but I am not too proud to ask and there are some very good engineers on this forum.

Thanks for anny replies.

 

[ProDave]

Yes. the fuse is labelled wrong. NOT at all uncommon.

Or perhaps the circuits are not really split up / down, more like front / back.

If pulling the "correct" fuse does not isolate it, then you just have to try them all in turn one at a time until you find the right one. then correct the labelling.

As others have said, don't rely on the fact the tv goes off to tell you that you have isolated the correct circuit. You need to TEST the actual point you are going to work on, to ensure it REALLY is dead.

The old mantra is "test your tester, test for dead, test your tester again"

 

[sprocketflup]

well the most obvious reason would perhaps be simple mis-labelling of the offending circuit breaker Id say.

Use your test equipment to ascertain what it does actually do and relabel it.

**edit**

lol beaten by a Pro ^^

 

[Doc Hudson]

You are going wrong by assuming things you have not proved yourself. I would never suggest that anyone relies solely on fuse box descriptions as a means to identify a circuit. More often than not descriptions are vague, incorrect or completely wrong. Also only use an approved voltage tester to verify conductors are actually dead. Beware of crossed conductors or lose conductors, i.e. missing neutral may appear dead if you are testing between live and neutral, however there could still be 230v on the live.

Doc H.

 

[SLIPSHOD & SLAPDASH]

Or..................  The sockets were labelled correctly including the taped up connections & the bedroom tv socket was connected to a different circuit. So as others have said you must test  at the point you are working on.

 

[Evans Electric]

Max   ...one of the basic but most important rules of thumb has arisen here ,  the other members have already highlighted it .

NEVER ASSUME ANYTHING .

So :

1)    Never assume its dead .

2)    Do not take someone else's word that its dead.

3)    Never assume your tester is working .

4)   Never assume fuseboards are marked up correctly. 

5)   Never assume the guy before you knew what he was doing .

6)   In your case , do not assume that ALL the plugs upstairs are now dead because the upstairs fuse is now in your pocket. 

7)    Do not assume that everyone counts from  left to right when marking up boards .     (  Many sparkies raised on the old Wylex domestic coloured spot boards still count from the right )     (( There will be some on here I know the're will ))    

 

[ProDave]

And (from experience) do NOT assume the whole house is dead, just because the main switch in the consumer unit is "OFF"