professionally fitted new CU bypasses lighting circuit ?

[lostinthewoods]

Hi all sparkies

I've just had a professional (NICEIC etc) electrician install a new CU at my house (that I'm away from at the moment and renting out so can't get to see what he's done easily). When the tenants move out I'd like to get the lighting circuits rewired but I can't have it done while they're in residence.

It's a split load CU with RCD. It replaced an old style black fuse box plus a separate lighting installation (a separate black unit). Except he has left the old lighting installation in place. He says it is too delicate too touch - this may be true. But I keep asking the question - which he refuses to answer - 'does the power go through the CU and then onto the old lighting installation, or does the power bypass the CU and go direct to the old lighting circuit i.e. the lighting circuit is not protected by the CU'. And I am getting very nervous that he WILL NOT answer this question (asked 4 times in writing now).

So I ask the resident sparkies: even if we take it as true that the old lighting installation is delicate and should not be moved, surely it can still be wired inline with a new CU ? Surely it is completely missing the point for the lighting circuit to bypass a new CU ? Please help...

I'm asking this because there a lot of things this 'professional' has done which mean I have approaching zero confidence in him or his work, and I would appreciate a couple of second opinions on this...

Thanks.

 

[THRIPSTER]

What does the Electrical Installation Certificate that he has handed you say on it with regard to the lighting circuit?

 

[lostinthewoods]

he hasn't done this yet (although the work was (theoretically) completed at the end of September...). But I am chasing up very keenly on the Part P certificate, which he says he will issue with a recommendation to re-wiring the lighting circuits at a later date - which sounds appropriate to me.

My question that he will not answer is, until this happens, what is the situation regarding the lighting circuit ? is it protected through the CU or not ? And my question to this forum is, is it reasonable to leave a lighting circuit outside a CU ? even if the lighting installation is 'delicate', surely it could be connected in line without moving it until the rewire takes place ?

thanks for your response

 

[securespark]

Why is it important that the lighting wiring goes through the new CU?

 

[lostinthewoods]

I don't know if it is important or not - that's what I want to find out.

What I was expecting from the work specification was that the whole house would have a single main on/off switch on the CU so that it could be turned off easily in case of an emergency.

If the experts want to tell that it's quite normal that the lighting circuit is separate from the CU (where the RCD is), then I'll be happy. It just seemed counter-intuitive to me.

And thanks everyone for having the conversation with me - its been frustrating just being stonewalled on this one by my electrician.

 

[Adam_151]

It sounds like you had two consumer units before, a main one and a separate one for the lights, and he has replaced the main one and left enough room for the lights, but not connected them upto that because your lighting circuit is old and possibly in VIR (rubber cable... we use PVC these days) There is two things that could have been done, the lighting CU might be supplied from the same place as the main CU, or the lighting CU might be fed from a submain running from the main CU, to find out, you can either look at which way the wires run, or switch off the main switch in the main CU and see if the lights go off.

When feeding multiple CUs from the supply, its good practice to have a separate switch before you split the tails (the main wires from the meter) in service connector blocks, so you have a 'main switch' however the regulation in this area is a bit open to interpretation, and quite a lot of houses have no overall switch

 

[lostinthewoods]

Thanks Adam_151, your reply makes a lot of sense.

I can understand that it might be more prudent to leave an older lighting CU untouched (yes, it is VIR - that much the electrician DID tell me. But not what VIR was). But if I understand you rightly, it sounds like there are various possible solutions that would allow this and still allow for a 'main switch' i.e. adding in a switch before the meter tails split.

Thanks again.

 

[securespark]

The only danger in this arrangement would be if your supply was TT. (Overhead (or more rarely underground) supply cable with no earth connection provided by the DNO. Instead, there should be an earth rod nearby.

In this case, the lighting needs to be protected by an S type RCD.

 

[Adam_151]

VIR = vulcanised india rubber, expected lifetime from it is 25years...and they stopped installing it in the 60's .... the problem is that it dries out and the insulation drops off if you move it sometimes

You may still have an overall switch as I said before... the old unit may now be fed from a breaker on the new unit and the main switch on the new unit is the overall main switch (easiest way to find out is to opperate it), or if its been branched off before the new CU, there might be a main switch fitted before the cable splits (have a look). But its also possible that there isn't an overall switch, its not an uncommon situation for there to not be one, different sparkies will have different interpretations on whether or not the regs require it

As said by secure, its unlikey the lighting will be on an RCD regardless of its age unless you have a TT install (simple reason is that the danger of shock from lights is less than other circuits*, and if it nuisense tripped, stairwells in darkness could lead to injuries...)


*for a start you are unlikely to be gripping a light, especially not while standing barefoot in a puddle

 

[lostinthewoods]

Thanks securespark, that's helpful too.

I'd be interested to know what people would have reccommended as a best practice wiring solution in his scenario ?

 

[markthebuilder]

adam 51 am I right in believing that had the electrician moved the lighting circuit to the new CU he would be responsible for it and if it was defective (not up to current standards)he would be on a dodgy wicket and would not be abel to issue a part p cert by not moving the lights he will be able to issue a part p cert that excludes the lighting circuit

 

[dingbat]

There is no such thing as a Part P Certificate!

Your spark should have issued an Electrical Installation Certificate (in accordance with BS 7671) and notified building control. The notification should have been prior to work commencing work, or, if he is self-certifying, within 30 days of completion.

If the former then the local building control office should issue you with a certificate of compliance with building regulations, if the latter this compliance certificate will come from his registration body.