different lighting wiring

[tbs1983]

Hi Guys, I'm from a mainly industrial background so looking for an experienced domestic sparky who can help out.

My mate asked me to change a couple of old pendants in his house for new ones.
Went there tonight to do them, in both pendants (different rooms) were 3 x double insulated single cores. One of which was connected to the line side of the rose, and the other 2 were connected to the neutral. (no earth present, not uncommon in older lighting circuits)
I thought it was strange but thought there may be a borrowed neutral case going on or something.
On disconnecting the old pendant I powered up and was surprised to see that I was getting 230v across the 2 cores connected to the neutral side.
Anyone come across this type of wiring method before? I can't fathom it out to be honest. I assume there are JB's above in the ceiling somewhere but why the need for this rogue 3rd neutral core that is seemingly live?

Any help will be greatly appreciated!

 

[tbs1983]

Thank you showerman! The lightbulb has literally just switched on in my head !!!! Makes perfect sense now!!!

Why didn't I think of that before !!!!

Thanks guys for all the help, the case is now closed!

 

[Pete999]

Can't see the lives from the neutrals lol

 

[KAS1]

If you split the 2 blacks them "power up" and measure across the 2 blacks If there is another light switched on somewhere on the circuit you will of course pick up 230v across the 2 blacks lol

 

[MDJ]

Can't see the wood for the trees you mean Pete

 

[Pete999]

Yep something like that.

 

[R G]

If it was working before and you have i/d off the live return wire to the pendant , and the other cores were in the neutral bar , then no problem , the reason you are getting 230v between the neutral is because the its the return through the other lamps on the circuit .

 

[tbs1983]

Cheers Ray, understand it now. Thanks for the help (and the usual sarcastic comments from the trolls).
Done a bit of new housebashing but Not worked on 2 many older installations. Once the wiring method was established by the very helpful Pete, the answer to the voltage problem made sense.

Thanks again

 

[MDJ]

(and the usual sarcastic comments from the trolls).

Nothing Sarcastic at all, you were encouraged to think about what happened, you understand now and got your answer, don't be so Touchy :troll: