Borrowed neutral discovered when changing CU and discussion on DIY CU change

[rsmck]

My usual disclaimer applies - I'm not a professional electrician..

I recently changed the CU in a family member's home as a bit of a stop gap (they are building an extension later next year and will have the property fully rewired then - but for now they asked if I could replace the traditional rewireable fusebox with a modern CU with RCD protection)

One room (not a hall stairway or anything like that) has two-way switches and the irritating issue of a borrowed neutral. I know the 'proper' solution is to provide a new neutral - but as the property is being rewired in a year or so anyway and there's no easy way to run this in without extensive redecorating it's wasn't a viable option.

I've put both the upstairs and downstairs lighting circuits on the same RCD (again, would rather not, but it means they have light!) and marked the new CU with a note stating that the lounge lighting has multiple means of isolation and the relevant circuit numbers.

Is there anything else I could do to improve this situation that I may have overlooked ?

As an aside, replacing the CU also showed two FCUs which, when fitted initially, appear to have had a screw cut into the insulation of the live cable. Presumably these screw heads have been live for many years and no-one has touched them, but certainly made replacing the CU worthwhile

 

[MDJ]

Re: Borrowed Neutral discovered after changing CU

I'm not a professional electrician..

I recently changed the CU in a family member's home

:shocked: :toetap05: :leaving:

 

[rsmck]

Re: Borrowed Neutral discovered after changing CU

:shocked: :toetap05: :leaving:

I was waiting for (although optimistically hoping I wouldn't get) that response

The change has been done safely. I've also rewired my last two homes (and had some very helpful advice from others on here)

Despite not being a professional electrician I do have a good understanding of electrical concepts and *do* own and know how to use testing equipment, and conducted (and recorded the result of) full tests on my own installation mainly for my own reassurance - I appreciate it's not valid as a certificate.

Not all "DIYers" are the same....

Now, any other useful suggestions

 

[ian.settle1]

Re: Borrowed Neutral discovered after changing CU

Hope you have notified the LABC or you are breaking the building regulations:6::detective:

 

[trev]

Re: Borrowed Neutral discovered after changing CU

An expensive way of carrying out a relatively easy fix to that problem mate. Presumably the new CU will continue to be in service after you do the rewire.

 

[rsmck]

Re: Borrowed Neutral discovered after changing CU

Hope you have notified the LABC or you are breaking the building regulations

No I'm not. No notification is required in that area.

 

[MDJ]

Re: Borrowed Neutral discovered after changing CU

. I've also rewired my last two homes

Gasp :uhoh2:

 

[snowhead]

Re: Borrowed Neutral discovered after changing CU

Scotland?

 

[rsmck]

Re: Borrowed Neutral discovered after changing CU

An expensive way of carrying out a relatively easy fix to that problem mate.

A problem they never knew was there, the main reason for the replacement was that there's a damaged fuseholder and replacements aren't available. Seemed a good time to change it.

Presumably the new CU will continue to be in service after you do the rewire.

I won't be doing the rewire - any new wiring in a new build extension over 8m2 DOES require LABC notification and as they're getting a lot of work done the rewire will be part of that. I expect the electrician may choose to use the CU that's already there.

 

[bigbaddave]

Re: Borrowed Neutral discovered after changing CU

Shared nutural on same RCD or same MCB... Please say the latter....

 

[bigbaddave]

Re: Borrowed Neutral discovered after changing CU

A problem they never knew was there, the main reason for the replacement was that there's a damaged fuseholder and replacements aren't available. Seemed a good time to change it.



I won't be doing the rewire - any new wiring in a new build extension over 8m2 DOES require LABC notification and as they're getting a lot of work done the rewire will be part of that. I expect the electrician may choose to use the CU that's already there.

Depends what kind of job you have done, Ive done jobs in the past where the previous install must have thought 1.0mm cable requires a hole big enough to get two fingers in..

 

[9regnac]

Hope you have notified the LABC or you are breaking the building regulations

No I'm not. No notification is required in that area.

Do u not need to notify labc in Scotland??

 

[rsmck]

Re: Borrowed Neutral discovered after changing CU

Depends what kind of job you have done, Ive done jobs in the past where the previous install must have thought 1.0mm cable requires a hole big enough to get two fingers in..

All cable enters from behind so there's no huge holes in the side of the CU

 

[bigbaddave]

Re: Borrowed Neutral discovered after changing CU

All cable enters from behind so there's no huge holes in the side of the CU

Good lad......

 

[kingeri]

Re: Borrowed Neutral discovered after changing CU

When you've done can you come round and perform brain surgery on my wife? I know you're not a qualified brain surgeon, but as long as you do it safely and write down all the results on a bit of paper for piece of mind, it'll be fine.