New Single Story Extension - Dining Room/Lounge

Hi

Just wanted to start planning and get an idea of materials and setting out?

I am looking to do most (if not all the) first fix and have spark connect and test.

The existing wiring is on a RCD (10 yr old CU) and looks to have been split into a radial circuit. The new extension internally would require 8 - 10 double sockets, 8 downlighters and externally 2 weatherproof sockets and maybe 4 x IP65 lights.

Would you suggest we run a new feed (6mm?) off CU with its own sub panel with 32A mcb for sockets and 16A mcb for lights?

Or is it best to simply add new radial to existing CU again with their own mcb's (on 2.5mm & 1.5mm)?

Many thanks for any help/advice?

Cheers!

Rusty10 said:

I am looking to do most (if not all the) first fix and have spark connect and test.

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If you really must do that, get the electrician involved before doing anything.

Rusty10 said:

Would you suggest we run a new feed (6mm?) off CU with its own sub panel with 32A mcb for sockets and 16A mcb for lights?

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No, totally pointless.
Extend the existing circuits, or perhaps add a new one for the sockets depending on what is to be used in this room and what the existing circuit has on it now.

The installation certificate will have either one or three signatures for design, installation, inspection and testing, what you are asking is for forum members to the the design for you, we clearly can't do that, but we can give a few pointers.

In the main lighting circuits are limited to 6A, although the regulations does permit up to 16A, many ceiling roses and lighting junction boxes are rated at 6A so better to keep to 6A if you can.

As to having more than one person doing the work, this will likely mean you can't have the electrician raise a compliance certificate, some in England may be able to do it, but most in order to use a three signature installation certificate would need to work through LABC and get a compliance certificate so you would need to be careful to have the electrics on the application form with building control.

It may be that a mini consumer unit off main one is way forward or connecting to main one, however cable lengths will be important ensuring volt drop is not exceeded etc. Stage one is clearly to measure what you already have, then calculate what new figures will be, northing to stop you from doing it DIY if you have the skill, question is do you have the skill?

Rusty10 said:

Or is it best to simply add new radial to existing CU again with their own mcb's (on 2.5mm & 1.5mm)?

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Yes, but a new ring with 2.5 mm cable, radial is pretty pointless.
Lighting circuit on a 6a MCB (not 16), in 1.0mm cable. No point in using 1.5mm.

Hi

Many thanks to all the comments, really all I was looking for is to run appropriate cables before I renovate the existing house as floorboards are available and loft has yet to be boarded?

The cable run from the CU would be around 15m

Rusty10 said:

Hi

Many thanks to all the comments, really all I was looking for is to run appropriate cables before I renovate the existing house as floorboards are available and loft has yet to be boarded?

The cable run from the CU would be around 15m

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Then find your electrician NOW, explain what you are trying to do and seek his guidance on cable types, routes etc.
He may be OK with you then doing the basic grunt for him to do the next step.

I'm assuming the local authority is involved wrt Building regs for this project?

Taylortwocities said:

Then find your electrician NOW, explain what you are trying to do and seek his guidance on cable types, routes etc.

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Taylortwocities said:

I'm assuming the local authority is involved wrt Building regs for this project?

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Rusty - I don't know if you appreciate how important this is.

You will not find an electrician prepared to rock up after the event and sign documentation to say that he did the work. (Or, if you do, you'll basically be entrusting that certification to a criminal).

And if you, actively, or by allowing their default assumption to stand, tell the council in your application for Building Regulations approval that your route to ensuring compliance with Part P will be something different to what you then go and do, you'll be in a world of pain when it comes to getting a completion certificate out of them.

As above - get an electrician on board NOW - he can design the circuits, and may let you do some of the first fix under his supervision.

No one in their right mind is going to want to take on something an amateur has started.