L and N on different circuits


Postby 333rocky333 » Sun Dec 23, 2007 10:57 pm

Working on a large chain of stores,there lights are controlled by 240v contactors,
They have employed another company to fit a large timer control box to work them.

This has its own 240v supply, could be any phase!

They then run a multicore to the contacter box using seperate core for some of the contactor coils and removing existing live control wires.
some contactors are left on the old circuits with same existing neutral.

Instead of using a new core for the neutrals. they have left existing control circuit neutrals on the contactors.
This neutral now does the old circuits as well as the new supply contactors.

My concern is to replace the contactors or break the neutrals you would have to isolate both supplys, however if you did not know you would still have voltage and possibly 415v between neutrals
I think this is wrong as they are now bridging across two circuits and in some case two boards, and if old board turned off it would become live due to there neutral feeding back.

I am sure there must be a reg regarding this
does anyone know the number of it so I can prove them this
333rocky333
Posts: 182
Joined: Sun Nov 25, 2007 11:03 pm

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Postby BLAKEY1963 » Wed Dec 26, 2007 5:55 pm

333rocky333

i think this could be the outlawed practise of borrowed
neutrals.
NICEIC did an article on the dangers of it ,and was compiled
not so long ago , and can be lethal as you correctly point
out.
a phone call to niceic helpline will verify your concerns ,
confirm the reg ( as u already know rocky r changing jan 08) and help u address your concerns to the electrical installation firm
responsible for this work. on the grounds of health and safety and the electricity at work act u would have a duty to point out these concerns.

BLAKEY1963
BLAKEY1963
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Joined: Wed Jun 13, 2007 10:57 pm


Postby 333rocky333 » Wed Dec 26, 2007 10:03 pm

Cheers blakey

Have ordered new 17th regs book but wont get till late jan
Apparently just the quide book has some 600 pages , the actual regs book looks twice as thick.

Maybe something in there
Just cant find it in the sixteenth

I have reported it to my firm, they can sort it
Just nice to have something in print to back it up
333rocky333
Posts: 182
Joined: Sun Nov 25, 2007 11:03 pm


Postby 333rocky333 » Wed Dec 26, 2007 10:16 pm

borrowed neutrals, spot on found using that.
reg 314-01-04 covers bunching circuits and crossed circuits
333rocky333
Posts: 182
Joined: Sun Nov 25, 2007 11:03 pm


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