House rewire

[DIY1992Z]

Hi guys,

I'm renovating a 1920s 2 bed mid terrace I've just bought and I'm currently in the process of stripping everything to bare and I am planning on replacing all plumbing and electrics whilst I have opportunity

By trade I am a maintenance engineer in the food industry (mechanical bias but also electrical). I've not really done any domestic electrical work apart from minor things such as replacing fans, lights and sockets.

I am getting someone to test and sign off after I've done the work but just wanted to check a few things really before cracking on. I have done my 18th edition a while ago for my previous employer, but it was more of a tick box thing for them, rather than actually using the reg book (I don't own the regs book).

Could someone with a bit more domestic experience check over what I'm planning on doing with my circuits.

1 - lighting up and down, 6a RCBO 1.5mm radial
2 - Sockets up and down, excluding kitchen, 32a RCBO 2.5mm ring
3 - Kitchen sockets including appliances - 32a RCBO 2.5mm ring
4 - Cooker 16a RCBO 10mm radial
5 - Shower 40a RCBO 10mm radial

Does this make sense? Would the circuits be better separated more? All cables will either be in conduit in plaster or under floor boards. Advice welcome.

TIA

 

[EFLImpudence]

1 - lighting up and down, 6a RCBO 1.5mm radial

1mm² would be more than adequate but up to you.

2 - Sockets up and down, excluding kitchen, 32a RCBO 2.5mm ring

Ok. Standard arrangement but might not be best.

3 - Kitchen sockets including appliances - 32a RCBO 2.5mm ring

Ok.

4 - Cooker 16a RCBO 10mm radial

No. ???
32A with 4mm² or 6mm²

5 - Shower 40a RCBO 10mm radial

Depends on the shower.

Does this make sense? Would the circuits be better separated more? All cables will either be in conduit in plaster or under floor boards. Advice welcome.

Conduit will reduce the capacity of the cable.

This shows why you really must involve your electrician to supervise what you are doing if you want him to "test and sign off".

 

[DIY1992Z]

Thanks for the quick response EFLI.

Would you say it is good practice to separate up and down sockets? I couldn't see the sockets being used too much apart from your usual TV, internet and the occasional iron/hoover.

The reason for the 10mm cable for the cooker was that is what I was planning using for the shower rather than buying different cables. I can uprate the breaker for the cooker and ensure the shower is within spec.

Regarding the sign off, I was looking for advice from the electrician signing off the work but he didn't seem too worried. I originally asked the council to do the sign off as I wanted it doing properly, but the person I spoke to from building control basically told me not to bother going through them and just get my own electrician..

 

[AndyPRK]

You want 2 light circuits.

You don’t want a fault and be unable to turn any lights on.

 

[DIY1992Z]

You want 2 light circuits.

You don’t want a fault and be unable to turn any lights on.

Hi Andy,

I could separate both the sockets and lightings up and down to make 7 circuits, the CU I will be fitting has space for 8 due to size limitations where it will be installed. So that leaves me with one spare doing that, I think I was getting a bit obsessed with saving space in the CU.

 

[EFLImpudence]

Would you say it is good practice to separate up and down sockets? I couldn't see the sockets being used too much apart from your usual TV, internet and the occasional iron/hoover.

Yes good practice.
Ring circuits are an anomaly these days because of MCBs and only worth doing if the route is actually 'circular'.
Two or perhaps four radials might be better - it depends on the situation.

The reason for the 10mm cable for the cooker was that is what I was planning using for the shower rather than buying different cables. I can uprate the breaker for the cooker and ensure the shower is within spec.

Mmmm ok. It is a waste, though.
6mm² might be enough for the shower, but again it depends - which is why you really do need someone knowledgeable on site.

Regarding the sign off, I was looking for advice from the electrician signing off the work but he didn't seem too worried. I originally asked the council to do the sign off as I wanted it doing properly, but the person I spoke to from building control basically told me not to bother going through them and just get my own electrician..

Oh well done to you.
Not so well done on the part of the BC.

 

[EFLImpudence]

You want 2 light circuits.

Yes, indeed.

I took 'up and down' to mean two circuits each for lights and sockets plus kitchen sockets.

 

[AndyPRK]

For a 2 up 2 down 2 socket circuits seamed ok

If every downstairs socket it going up to the ceiling then a ring seamed good.

If downstairs skts cables are staying down stairs then have separate circuits.

 

[DIY1992Z]

Thanks guys, much appreciated. The house also has solar panels installed with its own isolators and RCB. I've still to figure out exactly how this is wired etc since solar panels are new to me. Provided I isolate the solar system, I don't need to touch any of the wiring since it was installed in 2012?

 

[flameport]

Provided I isolate the solar system, I don't need to touch any of the wiring since it was installed in 2012?

You don't need to do anything - but it would be far better if the solar was put into the same new consumer unit with everything else.
10mm² is grossly oversized for a domestic cooker.
Electric showers are items of last resort, use the gas boiler instead if there is one.
A ring is only of value if there is only one, and it does all of the sockets in the house.

I was looking for advice from the electrician signing off the work but he didn't seem too worried.

Members of schemes can't notify other peoples work to building control - only their own work.
If you are doing the work, then it should be notified to building control by you before the work is started.

but the person I spoke to from building control basically told me not to bother going through them and just get my own electrician..

which basically means they couldn't be bothered with it, and want you to have an electrician do all the work and the notification.

You doing the work first and expecting it to be notified afterwards will result in problems.

 

[Taylortwocities]

Whssign

• Taylortwocities
• 16 Jul 2016

What he said

 

[ntipp]

I have recently moved into a similar aged property and the whole house needed rewiring which was a nightmare. My 16-year-old son had just one plug socket in his room which wasn't practical enough. We got ******** in to do it because I'm not electrical savvy enough. However, your circuit arrangement sounds good to me as they described what they need to fit and what you said was exactly the same!

MOD: Company name removed.

 

[John D v2.0]

There's debate about whether having only one lighting circuit would even comply with regs, in ours I actually split it into three - downstairs, upstairs and hall/stairs/landing so that at least you can see to get down the stairs.
There's no reason not to have two consumer units if you have an awkward space, you can put the 10mm cable to good use as a sub main. But in your case it sounds like you're ok.
Another gotcha just in case, you can have a 8 way consumer unit but you need 2 ways for the main switch, so just to be sure you took it into accoiunt. Since you're using RCBOs you neednt worry about the ways used by an RCD though.

 

[JohnW2]

There's debate about whether having only one lighting circuit would even comply with regs, in ours I actually split it into three - downstairs, upstairs and hall/stairs/landing so that at least you can see to get down the stairs.

Do I take it that you also have some battery-backed-up emergency lighting on your stairs? ....

As I so often point out, no amount of splitting of circuits will prevent one being 'plunged into darkness' in the event of a power cut - and, at least in my experience (where I live), power cuts (albeit often fairly brief) are far more common that MCB or RCD trips!

Kind Regards, John

 

[AndyPRK]

I wouldn’t want Landing and hall on same circuit.