CU change only one lighting circuit ???

[ianphilip007]

hi there

need a little advice when you change a C.U that currently has only one lighting circuit covering the whole property( upstairs and down) this circuit would need to be split into 2 seperate circuits before beeing connected to the new CU is my thinking correct re reg 314??

 

[Knobhead]

Believe it or not Knob and Tube wiring is still OK in some US states!

View attachment 12480

 

[Rockingit]

Believe it or not Knob and Tube wiring is still OK in some US states!

View attachment 12480

My knob and tubes have always had a good polish in the States.

 

[Mr.Ian]

So you all put lighting on a single supply ?
Well it looks like i'm not on my own as this is a quote from Bill Allan from N.A.P.I.T.

Lighting circuits - In the 16th Edition, lighting circuits would not use 30mA RCDs for additional protection because of the possibility of nuisance tripping, leading to the potentially dangerous scenario of people being left in the dark. In the 17th Edition, however, the requirement of Regulation 522.6.7 means that such additional RCD protection applies also to lighting circuits. To eliminate the risk of both lighting circuits going off simultaneously because of nuisance tripping, I've put each lighting circuit on a separate RCD.

 

[Darkwood]

Dont forget the BS7671 is not law! It is advised - you should follow it as much as possible unless you have a good reason not to - customer would not pay for a rewire is an ok reason

Do an Ohms law if your in doubt:
P=IxV
I=P/V
= 1000/230
=4.35A

Use a 6A MCB and you have more than enough room to move with.

If in doubt change all the bulbs to Energy Saving - you would only get a max of 140w (based on 10 lights at 14w Energy Saving Bulbs - 0.6A

Although i doubt O/P will have any issues here; try not to give the impression that fitting energy saving lamps will give the circuit design current more lee-way, the circuit should always be calculated with the max rated lamp that can be fitted to the outlet, additional to this a 1.8 factor needs to be applied to inductive lamps, and in the O/P's favour diversity can be applied when working out demand on the circuit too.

 

[DPG]

Nobody would put the lights all on one circuit on a new system, but neither would they try and get money out of someone to change an existing system just because the cu was being changed. My thoughts anyway. Daz

 

[Rockingit]

Nobody would put the lights all on one circuit on a new system, but neither would they try and get money out of someone to change an existing system just because the cu was being changed. My thoughts anyway. Daz

Exactly! We split where we can (and often in my installs to 3 or 4 circuits on a new build big house), we lose no sleep where we can't.

 

[SirKit Breaker]

This thread seems to be another case of regulations overcoming common sense. You can only do what you can do. If you have upgraded from rewireable fuses to MCB's, then you have made the set up a lot safer. Ok you loose all the lights cos its on one circuit, just as it was before you started, but you dont need to fumble around rewiring the fuse, just reset the breaker, either way you need a torch, but its a lot less hassle, especially if your client is older.

My mind boggles sometimes at the arguments that get thrown up about application of the regs.

Cheers...............Howard

 

[Dave 85]

I priced a C/U change in a 1 bed flat with only 4 circuits (1 lighting) I phoned elecsa and they reckoned it was perfectly satisfactory to put in a single RCD board. I quoted £230 for this. The guys jaw nearly hit the floor, another firm had come in and quoted £750.
Another very happy customer.

With regards to the whole regs vs common sense thing, I totally agree. You're never gonna make any money if you spend your whole life buried in a regs book desparetley trying to find reasons to force the customer into having unnecessary work.
I havn't opened my regs book for months.

The way I see it, when you stick in an RCD board you're making the place 10 times safer than it was before. Theres no point losing jobs because you're insisting on making the whole house how it would be as a brand new installation.

 

[LukeBuckaz]

Agreed, the installation would have been left in a much more user friendly state than it was before.

Would you like a plumber to change your boiler then say "sorry got to split your upstairs and downstairs radiators into different zones and its gonna' cost you £400" ?

 

[SirKit Breaker]

I priced a C/U change in a 1 bed flat with only 4 circuits (1 lighting) I phoned elecsa and they reckoned it was perfectly satisfactory to put in a single RCD board. I quoted £230 for this. The guys jaw nearly hit the floor, another firm had come in and quoted £750.
Another very happy customer.

I agree it is compliant, and acceptable, but i would have charged £400 and used RCBO's, but that is down to the customer i suppose.

Cheers..........Howard

 

[Dave 85]

I priced a C/U change in a 1 bed flat with only 4 circuits (1 lighting) I phoned elecsa and they reckoned it was perfectly satisfactory to put in a single RCD board. I quoted £230 for this. The guys jaw nearly hit the floor, another firm had come in and quoted £750.
Another very happy customer.

I agree it is compliant, and acceptable, but i would have charged £400 and used RCBO's, but that is down to the customer i suppose.

Cheers..........Howard

Aye and I'd of got the job
I rarely even bother trying to suggest RCBO boards to people these days (I'll admit, I hate installing them) they usually look baffled enough when I try and explain what an RCD is and would rather pay £350 for something they don't understand or particulalry want (15 way board) than £600 for something they still dont understand and is no safer.

 

[Knobhead]

The more I see of these posts the more convinced I become that some electricians use the regulations as “the law” and browbeat customers in to unnecessary work. I know that most of you are honest and upright tradesmen.

There’s only one law I believe in.

View attachment 12483

 

[mark ju]

If you want to take this to the extreme then every room should have it’s own MCB. BUT a room may have a centre light and wall lights, so that’s two MCB’s. One step further and each room should have it’s own radial for the sockets. We will finish up with every house having to have Sizewell B switching station under the stairs.

Hey lets do that then. i like doing consumer units/distribution boards. More circuits the merrier. makes it more of an interesting job!

 

[pencilpusher]

My knob and tubes have always had a good polish in the States.

My knob is fine but my tubes don't work any longer since visiting the US!

 

[Rockingit]

My knob is fine but my tubes don't work any longer since visiting the US!

We clearly visit different bars.