Why did I not die??

[calumr135]

Hi all, I was changing a ceiling light in a very old property, the whole lighting circuit is wired in singles and in conduit, upon replacing the light fitting in the ceiling was a rather unusual set up, there were four wires in the rose, the live wire which was a single yellow for some reason?, an earth wire and 2 black neutrals? upon testing it showed no voltage so I assumed it was dead however disconnecting the neutrals I got a pretty nasty jolt! I felt a huge tingle running down my arm, to my surprise I noticed the 2 neutral arcing together, I then tested again and sure enough there was 245v reading on the multimeter!.

Couple questions
1: Is this setup common? like a borrowed neutral perhaps? I thought originally the loop was in the switches?
2: Why the hell did I not die? I thought touching both live and earth or live and neutral is garanteed electrocution? My finger and thumb were on both neutrals at the time of the shock, maybe I am just lucky but Im surprised it didn't kill me or knock me off the ladder. It was quite a strong shock and cut my fingertips a little.

I guess the moral is switch of the power in future even if the loop does not appear to be in the rose.

 

[DaveHerns]

Most of us have had an electric shock at some time and survived. However it's not wise to push your luck!

 

[wv62]

As Dave says above most of us have electric shocks at some time or another. I've had a few at voltages a lot higher than 240 before now. The severity of the shock depends on lots of factors including the path taken through the body to earth, how moist (sweaty) you skin is plus a whole lot more. To be safe ALWAYS check for dead before you start and with a proper test instrument and NOT a volt stick!

 

[JohnW2]

To be safe ALWAYS check for dead before you start and with a proper test instrument and NOT a volt stick!

Indeed. However, if, as is quite possible, the OP's unfortunate experience was due to a borrowed/shared neutral, then it is very difficult to detect the potential problem by any testing, with any test equipment. So long as the neutral conductors are all connected (as will be the case when 'testing for dead' before one 'touches anything"), there will be no voltages detectable anywhere. It's only if there are two or more neutral conductor and one disconnects one of them that, in the presence of a shared/borrowed neutral, one of the neutrals may become live.

Kind Regards, John

 

[winston1]

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.

In future switch off at the CU, you may not be so lucky with your next shock.

 

[calumr135]

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.

In future switch off at the CU, you may not be so lucky with your next shock.

I definitely will man, not taking any chances next time, Power off in future, ! I will just count myself very lucky. There is also no rcd in the property just an old style fusebox like I say its a very old property so its hardly surprising. Lesson learned the hard way!
cheers

 

[ban-all-sheds]

There is also no rcd in the property

That could be fixed.

 

[gram1980]

When working on circuit I’m even slightly dubious of I alway check voltage to earth between neutrals when disconnected to make sure it’s all dead.
Had my first tingle in a few years last week when I pulled down a light fed from the house next door and that was after I ripped out the fuseboard (of the house I was working in!)

 

[JohnW2]

When working on circuit I’m even slightly dubious of I always check voltage to earth between neutrals when disconnected to make sure it’s all dead.

That definitely makes sense, for the reason I've described, but one obviously has to be very careful not to touch any of the neutrals whilst disconnecting them.

The safest approach is, of course, to kill the entire installation before working on it.

Kind Regards, John

 

[ban-all-sheds]

With an unknown one, yes

 

[pete50]

Hi all, I was changing a ceiling light in a very old property, the whole lighting circuit is wired in singles and in conduit, upon replacing the light fitting in the ceiling was a rather unusual set up, there were four wires in the rose, the live wire which was a single yellow for some reason?, an earth wire and 2 black neutrals? upon testing it showed no voltage so I assumed it was dead however disconnecting the neutrals I got a pretty nasty jolt! I felt a huge tingle running down my arm, to my surprise I noticed the 2 neutral arcing together, I then tested again and sure enough there was 245v reading on the multimeter!.

Couple questions
1: Is this setup common? like a borrowed neutral perhaps? I thought originally the loop was in the switches?
2: Why the hell did I not die? I thought touching both live and earth or live and neutral is garanteed electrocution? My finger and thumb were on both neutrals at the time of the shock, maybe I am just lucky but Im surprised it didn't kill me or knock me off the ladder. It was quite a strong shock and cut my fingertips a little.

I guess the moral is switch of the power in future even if the loop does not appear to be in the rose.

Some are lucky some are not. Looks like you were one of the lucky ones..................this time.

 

[JohnD]

the unlucky ones never write about their experience.

 

[JohnW2]

With an unknown one, yes

Indeed - but, with only a relatively few exceptions, it is rarely the case that one can be absolutely certain that there are no potential 'surprises'.

I know the installation in my house well enough, and am certain that nothing has been done to it without my knowledge, that I am comfortable that it presents no potential surprises of the sort we are discussing. It is rarely the case that I could have such confidence with any other installation, so I do sympathise with electricians who spend much/most of their time dealing with "the unknown".

Kind Regards, John

 

[mwatsonxx]

This dummy didn't get electrocuted

 

[JohnD]

there were four wires in the rose, the live wire which was a single yellow for some reason?, an earth wire and 2 black neutrals?

Did you make the mistake of assuming that a black wire is a neutral?