New extension Wiring

[HVliney]

I qualified as an electrician a few years back (not Part P), but decided to pursue other avenues so am a little out of touch on the regs and have a few questions if someone could help

My sister is having an upstairs extension to her bungalow and she has asked me to do the electrics. I need to ensure it complies with the 17th edition, and building regs, as she will need a Certificate for the building inspector to issue a completion notice.She having a couple of double sockets each in the two bedrooms ,one double socket in the landing ,lights and a bathroom extractor fan At current the bungalow has an old consumer unit. Do i have to change it to comply with Part P/17th regs as sockets have to be rcd protected and something about i need to have atleast two spare mcbs? Also can you still extend the ring circuit with the use of junctions boxes? if so can i simply rcd protect the downstairs ring then extend to upstairs or do i need to run a new ring for the upstairs?Will i need to touch the downstairs wiring to make sure it complies or just the new extension wiring. Also roughly how much to get this sort of work certified by a third party?

Any help would be great

Thanks

 

[1john]

If she is having new joists installed it might work out easier to rewire the whole place as the cables will be in the way of the new joists if they've been strung across the loft.

I wouldn't think you would require a ring final circuit for two bedrooms and a landing, perhaps two 16A or one or two 20A radials will suffice, current demand is generally low in a bedroom with the occasional blast of a hair dryer or other hair heating devices and the vacuum, most appliances used in bedrooms tend to be low current consuming.

If its an old property then there is more than likely only one ring final circuit so extending that is not really a good idea.

16th edition regs were keen on and socket liable to be used out of doors to be RCD protected, the 17th edition like almost everything to be RCD protected. You will find it easier and cheaper to have a replacement consumer unit, remember your going to create another lighting circuit and that will probably need to be RCD protected too unless you have very deep walls, are handy with a conduit bender or know how to install pyro/mims/micc.

Check bonding is up to date / present!

Food for thought, unless you wanna do a lot of reading, perhaps go back to school, buy new literature then it may be easier to get someone in, they may let you do the grunt and bones of it mind, but check first. Also what are your provisions for testing the installation, have you got test equipment?

 

[PrenticeBoyofDerry]

If it was me doing the work I would recommend for simple ease of installation and compliance to electrical requirement.
That you first do a conditional report on existing installation.
Once that has been done, perform any necessary remedial work, so it is fit for service and compliant, if this can easily be done. If not consider rewire.
Then install CU which in-cooperates RCD protection, a number of methods this can be done.
You will ideally require at least two RCDs but could go for RCD and RCBOs combo or just RCBOs.
You only require one upstairs socket circuit and a 20A radial would be sufficient.
Also a separate lighting circuit for upstairs, would be ideal.
If you split/share your circuits correctly over two RCDs, you will ideally have both downstairs sockets and upstairs lighting circuits on one RCD and
upstairs sockets and downstairs lighting circuits on the second.
I would also consider having the boiler (if there is one) on it's own supply, via RCBO, to help prevent nuisance trip and frost damage issues.

Junctions can only be made where the joint is easily accessible for means of maintenance, inspection and test.
There are allowances in BS7671:2008 (AMD 1) that will allow maintenace free (MF) boxes to be used. But the new work you are carrying out, should be carried out in a manner that will avoid such connection/joints being made anyway!


I would suggest you get up to speed with current requirements
Purchasing the on-site guide (OSG) will help with the understanding of some of these.
If you are a qualified electrician a third party may not be required providing you have knowledge of inspection and test procedures and access to testing equipment (which can be hired).
May have to brush up on your knowledge of RCD tripping times and form filling though. But not rocket science and sample forms can be found in the OSG as can testing procedures.
Also a few free downloadable guides that you may find useful, can be found here:
http://www.esc.org.uk/industry/industry-guidance/best-practice-guides/

 

[HVliney]

Thanks for your quick responses

I think i will change the CU and run new radial or ring upstairs and new a lighting circuit. I was hoping not to touch the downstairs wiring at all just rcd protect the circuits in the CU while am changing it , however lets just say the dowstairs wiring aint up to scratch will that affect the issue of the certificate or do i only have to worry about the new work being complaint as thats the work notified to building control?

Getting someone in would be ideal but finances are an issue so i have offered to do the work for pretty much nothing. I do not have any test equipment so i will be definately looking to get a third party to test and certifity hence why i want to make sure its up to the regs

 

[ban-all-sheds]

My sister is having an upstairs extension to her bungalow and she has asked me to do the electrics.

When she applied for Building Regulations approval, what did she say, or allow to be said, or by default accept, would be the way that the electrical work would be done?

She cannot ignore what her LABC are now expecting, because if she does something different she could well end up unable to get a completion certificate from them.

Also roughly how much to get this sort of work certified by a third party?

What do you mean by "certified"? What are you hoping the third party will do, and does it agree with what the LABC are expecting to happen?

however lets just say the dowstairs wiring aint up to scratch will that affect the issue of the certificate or do i only have to worry about the new work being complaint as thats the work notified to building control?

Changing the CU is also notifiable.

You don't have test equipment - does that mean you plan to swap the CU with no testing first? Do you plan to energise it with no testing?

I do not have any test equipment so i will be definately looking to get a third party to test and certifity hence why i want to make sure its up to the regs

Same Q as above. Depending on what you mean by "certify" and what the LABC expect, you might find that you simply cannot just get someone in at the end to "certify" your work.

 

[JohnW2]

...a conditional report on existing installation.

That's an intriguing one - 'conditional' upon what, I wonder

Kind Regards, John