Feeding a loft

[landyman53]

Hi everyone

I am thinking of a future loft conversion in a '30s semi. I want to pre-feed services into the loft space in advance of the conversion (doing up a room below, make all the mess now!)

Can I run a decent sized cable, say 10mm T&E to the loft space from the CU so that a smaller CU can be installed in the new loft once converted?

Would this be the best way or should I run 2x 2.5 t&E plus 1 x 1.5 T&E for lights back to the existing CU?

I like the fist option as a dedicated CU in the loft would provide flexibility in the future.

Thanks for your help

Steve

 

[Spudnik]

Hi Steve and welcome.

If it is easier to run in one single cable then yes, a standalone CU supplied from downstairs is a good way to go.

However, this work is very notifiable to your LABC, so, you can either appoint a registered electrician to do it for you, or do the work yourself, but you must notify BC first, and they will come and check it over, if they have the means to do this, as some/many dont. BC will also charge you for this and it could be anything from £100 upwards.

 

[WarrenG]

Hello Steve,

You mention that the property is a 30s semi.

It may be wise for you to check that your current installation can take the additional demand that your are planning for it before you start any work?

A qualified electrician could assess this for you.

 

[landyman53]

Thanks for the replies.

I only want to run in a cable at this stage and leave it coiled both ends for future connection/use once the loft conversion takes place. The route is torturous and as I am having ceilings down and walls chased now, I could get the main cable in and prevent a difficult job later. I have to get a part P certificate so I guess I will have to employ an electrician then to use my cable and complete the job in the loft.

I had a qualified electrician install my kitchen and living room extension for a Part P and was disappointed with the job he made. Looking at the definition of "Competent Person", I beat him hands down!! I was helping him with calculations, earthing etc....

Oh, and the whole house was rewired back to the meter in 2001 with a split CU etc and the wiring is in excellent shape generally.

Just wanted to know the cable size for by disconnected link cable (and a separate earth of course!)

Thanks

 

[Paul_Rawlinson]

The problem is that a qualified electrican shouldnt test and commision the final ciruits when the lost conversion is done. This is because he has not seen where the cable(s) have been run, and wether they follow BS7671, i.e mechanical protection, safety zones etc... he would need to see it at various stages, in your case before it is plastered.

 

[landyman53]

Thanks Paul

I will of course install it to BS7671 and I propose taking pictures at each stage to clearly show the route and mechanical protection. fixings etc.

Then, once connected and tested, the electrician can use the pictures as back up evidence of a correct installation.

I think all installations with hidden wiring should be photographed during installation to show the home owner where the cables are run in the future. It would save and awful lot of "drilled" cables!!

When I had the extension wired, I photographed all the cable runs before plastering (with a guide measure) and this saved many problems and much time when I came to install cupboards later.

Just a thought.....

 

[Steve D]

If you're concerned with the future running of addition cables causing mess by chasing walls etc, might it be worth considering installing a duct or conduit in the wall in readiness for any future installation of cable.

That way, the installing electrician would be installing the cable himself so he would be sure of the method of installation.

 

[landyman53]

Hi Steve_D

You are right there and I have considered it but the route is around the underside of a staircase and quite inaccessible once the ceiling is replaced! There are too many twists and turns for conduit and using a flex conduit means the diameter would be too large.

I have been reading part P and it seems that if I notify Building Regs in advance of the work, I can do it all myself. I wont get a part P but I will get a completion certificate once done to their standard. This is good enough to go with a future HIP's apparently.

Has anyone ever tried this in practice?

Steve

 

[Steve D]

You may be able to do it, but the crux of the matter is that the electrician signing off the work needs to be satisfied that the installation method of the cable is satisfactory and does not deviate from BS7671.

 

[WarrenG]

Hi Steve_D

You are right there and I have considered it but the route is around the underside of a staircase and quite inaccessible once the ceiling is replaced! There are too many twists and turns for conduit and using a flex conduit means the diameter would be too large.

I have been reading part P and it seems that if I notify Building Regs in advance of the work, I can do it all myself. I wont get a part P but I will get a completion certificate once done to their standard. This is good enough to go with a future HIP's apparently.

Has anyone ever tried this in practice?

Steve

A completion certificate is not the same as an Electrical Installation Certificate to BS7671 which you may need if ever you were to sell your property or if it were to be requested for insurance purposes.

 

[coxy]

It is impossible to run a cable without knowing the exact loads it may take.When doing the loft conversion you may decide to install a shower etc.I have come across this so many times that you must prepare for the worst case.

 

[62patrick]

Hi, its just a point, but I think you need to consider BS5839, as you will be adding an extra room,

 

[landyman53]

Hi everyone

You have all been most helpful and I take all the points on board. I think my first call is going to be to building control at this stage. Ultimately, even though I can show that I am a "Competent Person" here, I will use an electrician to install the loft electrics and certify it all. I intend running hot and cold feeds plus heating flow and return pies into the space (capped at this stage) and wanted to add an electrical feed cable at the same time. This will save so much disruption later on and allow the trades in the loft to work "independently" of the rest of the house. As I know the electrical loads (no electrical shower, just a small ring main and a few lights, an extractor fan and a shaver socket) I calculated that a 10mm feed plus a 6mm earth feeding a localised CU in the loft would me more than adequate. It will be around 12m long and the volt drop will be nothing worth worrying about.

As I said before, I will photograph the installation at all stages as evidence of good and proper working practices. I wonder how many electricians would bother to do this?

Best wishes

Steve

 

[Spudnik]

I will photograph the installation at all stages as evidence of good and proper working practices. I wonder how many electricians would bother to do this?

Best wishes

Steve

A registered electrician doesnt have to because he signs the certificate stating that work is done in accordance with bs7671. The buck stops with him.

This is why you may find it difficult to find someone who is willing to put their name on something that they had no involvement in.

Also, the scheme operators DO NOT ALLOW 3rd party testing

I know i wouldnt UNLESS i inspected EVERY stage of the installation. Even then i still might not.

IF is was you , i would go down BC route.

Good luck!

 

[landyman53]

Hi Jason

That is fair enough and reasonable. I would not be comfortable signing off anyone elses work as my own!

I can see that 3rd part certification is not allowed but using a "Supervised Person" to do the work is. Maybe I should find an electrician to use me in this way? I want to do all the work on my own house, I know what I am doing and am just looking for a way to get my work certified.

Back to Building Control then.....

Thanks to all the people who helped here, great forum!