Why did I not die??

[JohnW2]

Which is what I said in a different way back in post 5:

... and, if we're playing that game, what I said in a different way back in post #4

Kind Regards, John

 

[JohnW2]

Nope, no twin and earth or 3 core and earth, just metal conduit and single wires

Yes, sorry, I had deleted that post - I'd forgotten that you told us that it was wired in singles.

Kind Regards, John

 

[333rocky333]

In old property like the OP was working, Yellow and Black wiring may have been possible and im sure i have seen it, if it was a single phase on a Yellow phase of a 3 phase RYB supply, i always thought it was allowed and the regs later banned it , but someone posted on here that it was NEVER allowed.
For once I agree with WINSTON for his usefull post.

 

[JohnW2]

For once I agree with WINSTON for his usefull post.

I never thought I would find myself saying it, but I essentially agree - albeit he was essentially repeating what had been said by at least two others (plus himself).

Kind Regards, John

 

[333rocky333]

Was refering to post 5, i realise now your previous post 4 said, borrowed/shared neutral , but i focused more on the word Borrowed too be honest

 

[333rocky333]

...

 

[JohnW2]

Was refering to post 5, i realise now your previous post 4 said, borrowed/shared neutral , but i focused more on the word Borrowed too be honest

Ah, I see.

Anyway, what is important is not 'who said it first' but, rather, the fact that we are all saying essentially the same thing - and, given that there was (luckily for OP!) seemingly no perm L at the rose (whether 'switched off' at the light switch or CU), I still think that a borrowed/shared neutral is really the only explanation for what the OP experienced - unless you (or someone) can think of something else?

Kind Regards, John

 

[EFLImpudence]

Anyway, what is important is not 'who said it first'

Ok.

but, rather, the fact that we are all saying essentially the same thing

Are you sure?

- and, given that there was (luckily for OP!) seemingly no perm L at the rose (whether 'switched off' at the light switch or CU),

It seems to have made little difference.

I still think that a borrowed/shared neutral is really the only explanation for what the OP experienced - unless you (or someone) can think of something else?

People already have.

 

[333rocky333]

I think he would have been luckier to have had a permanent live at the rose, at least on testing he may have noticed it and isolated at the FUSE rather than the switch.
Is it not called a LOOPED neutral

 

[ban-all-sheds]

With an unknown one, yes

Indeed - but....

Followed by reason after reason why what I said was sensible, and not one disagreement.

So why the "but"???

 

[JohnW2]

It seems to have made little difference.

I suppose that's true, but 'testing for dead' is really meant to be 'testing to confirm dead', not 'testing to see if it's dead" - i.e. if one thin ks that there is any possibility of their being a permanent live at the rose, one shouldn't be using the light switch to 'render it safe'.

People already have.

They have? What else has been suggested that could/would explain no voltages being present when the wiring was intact, but for a painful voltage to appear when the two black conductors were separated?

Kind Regards, John

 

[JohnW2]

Followed by reason after reason why what I said was sensible, and not one disagreement. So why the "but"???

Because, sensible or not, I believe that it is very rare that your comment would be relevant, since I believe that it is very rare that one can be absolutely certain that an electrical installation (other than one which one has lived with, and constantly 'supervised', for years) contains no hidden 'surprises'. In other words, almost any electrical installation has to be treated as potentially "unknown".

Kind Regards, John

 

[SimonH2]

I assume the yellow was a switched live and the neutrals were looped to other ceiling lights (I know you shouldn't assume, but this way is quite common with singles). Separating the neutrals would break the circuit to other lights and 240v would appear across them through the other lights.

That setup is quite common in old houses with conduit.

Indeed it would be the most sensible way to wire it if working with singles in conduit.
The shortest route for the live would be to daisy chain along the switches only, taking the shortest routes through the conduits. The shortest route for the neutrals would be to daisy chain round the ceiling roses, again taking the shortest routes through the conduits. That just leaves the switched lives from each switch to it's respective rose(s) - and it would be sensible to use a different colour to help differentiate this from other lives (it would certainly make it easier wiring the switches having two reds plus another colour rather than three reds), hence why the live to the rose was yellow.
At one time, there wouldn't have been any earth wires - they'd have just used the slip conduit for the earth, and I wonder how reliable that was after "some years".

 

[EFLImpudence]

They have? What else has been suggested that could/would explain no voltages being present when the wiring was intact, but for a painful voltage to appear when the two black conductors were separated?

It is probable that there was a light on that circuit turned ON in another room and the return current was traversing the Neutral connection. Breaking the Neutral connection created the potential difference.

It doesn't have to be a borrowed neutral.

 

[333rocky333]

Because, sensible or not, I believe that it is very rare that your comment would be relevant, since I believe that it is very rare that one can be absolutely certain that an electrical installation (other than one which one has lived with, and constantly 'supervised', for years) contains no hidden 'surprises'. In other words, almost any electrical installation has to be treated as potentially "unknown".

Kind Regards, John

Your house could be potentially more dangerous than most homes id quess.
Parting 2 neutrals, though unlikely you could unexpectedly find 400 volts, due to a problem elsewhere