Re-routing existing lighting cables, in the attic

ijrwe

Hi. The wiring for my upstairs lighting is currently routed very poorly through the attic and just lies across the various beams. I want to board it all out so have to get them tucked away somewhere. The wiring is quite old, I think, but I don't know when it was done. All the light switches are 30-40 years old, anyway.

I'm going to install an attic light from the last ceiling rose in the series, and this cable I will route entirely around the outside permiter of the attic where the boards won't reach. This seems like the sensible way to do it.

To get the existing cables out of the way, it seems like I have several options:

1) Notch the beams - not recommended?

2) Put new beams atop the current ones, raising the floor level but giving plenty of places for the cables to pass through everything.

3) Drill the beams - but if I was going to do this I'd need to take all the wire out of the ceiling roses to thread it through the new holes, and so while doing all that I might as well just...

...4) re-wire the whole thing to skirt the edge of the attic and avoid the problem.

I'd rather avoid it, though - seems like a waste of time, money and cable.

What have you done in this situation?

Thanks,

ValHaller

If the existing joists are not up to bearing the local load, then you will need to add a crossways layer of beams across the existing joists anyway. Otherwise you might find that you can raise the floor using 50mm square timbers crossways.

I would initially check the wiring - is it earthed? is it modern cable? is it in good condition? are the fittings in good nick? and if it was anywhere near dubious, I would bite the bullet and rewire around the edges before boarding, taking care to leave it all rewirable for future

ijrwe

ValHaller wrote: »

If the existing joists are not up to bearing the local load, then you will need to add a crossways layer of beams across the existing joists anyway. Otherwise you might find that you can raise the floor using 50mm square timbers crossways.

I would initially check the wiring - is it earthed? is it modern cable? is it in good condition? are the fittings in good nick? and if it was anywhere near dubious, I would bite the bullet and rewire around the edges before boarding, taking care to leave it all rewirable for future

It's earthed, old colours, and superficially in OK condition. Some parts of the grey housing are quite dented and scuffed from being trapped under boards, but that's all.

I presume re-wiring that much will be notifiable? I need to look into it.

ValHaller

Rewiring for this job should not be notifiable as you are only replacing components in a a existing system. But that is only my take on it.

Avoriaz

With wiring 30 to 40 year old or more, plus evidence of some squashing, my instincts would be a completer rewire before you board over.

Are you capable of doing that yourself safely? (assuming that is legal)

If yes, then it won't be very expensive.

keystone

ijrwe wrote: »

The wiring is quite old, I think, but I don't know when it was done. All the light switches are 30-40 years old, anyway.

How old? Is it rubber insulation or PVC? Is it grey with harmonised cores or is it white with red black and earth. Does it have an earth?

I'm going to install an attic light from the last ceiling rose in the series, and this cable I will route entirely around the outside permiter of the attic where the boards won't reach. This seems like the sensible way to do it.

Go along the side of the joits to the hatch which is where you put your switch. Then continue along the joist until you can run it up a rafter to the place where you want to put the light.

1) Notch the beams - not recommended?

Notch for pipes, drill for cables.

2) Put new beams atop the current ones, raising the floor level but giving plenty of places for the cables to pass through everything.

Yes provided the additioanal loading is OK as has been advised. In this case you do not need to do anythging with your cabling.

3) Drill the beams - but if I was going to do this I'd need to take all the wire out of the ceiling roses to thread it through the new holes, and so while doing all that I might as well just...

As above and why is that a problem?. BTW A couple of sparks I know maintain that all the cabling should go up the rafters and drop vertically down to the light fitting. PVC forest!! Comes awfuly expensive in cables though but.

...4) re-wire the whole thing to skirt the edge of the attic and avoid the problem.

I'd rather avoid it, though - seems like a waste of time, money and cable.

I think I agree.

If you need junction boxes do not use these:



if they will be inaccessible. If you are using new harmonised cable but the majority of your cable has white outer and red/black conductor insulation make sure you put one of these:


on your consumer unit.

Cheers

keystone

ValHaller wrote: »

Rewiring for this job should not be notifiable as you are only replacing components in a a existing system. But that is only my take on it.

It is notifiable if he goes anywhere near the CU with his new cable. Only a registered sparky should touch the CU.

Cheers

keystone

Avoriaz wrote: »

With wiring 30 to 40 year old or more, plus evidence of some squashing, my instincts would be a completer rewire before you board over.

Very valid observation but OP did say that some of the fittings were that old not the cable but perhaps its not to far a stretch to suspect the age of the cable too.

An EICR would give OP all he needs to know to make a considered decision.

Cheers

Gloomendoom

keystone wrote: »

How old? Is it rubber insulation or PVC? Is it grey with harmonised cores or is it white with red black and earth.

Isn't a grey sheath with black and red cores also an option?

keystone

Gloomendoom wrote: »

Isn't a grey sheath with black and red cores also an option?

Of course it is - good point.

Cheers

ijrwe

Thanks for the replies. The cable is grey outer, with red, black and bare earth. The earth has been sleeved with solid green in one of the light sockets, which I think helps to date it as well.
Elsewhere in the house is green/yellow sleeved earth, though.


I drew up some generalised plans to show you guys the situation:

1) Basic attic floor plan. The attic space does extend beyond the boundaries shown but the floor kind of dips down a bit there, it's hard to describe.

http://i.imgur.com/XaDpx.png

2) What's underneath.

http://i.imgur.com/kEfzP.png

3) Current cable layouts. Origin is in the top right, final light and switch are on the left. The first ceiling rose on the circuit (i.e. in the middle of the diagram) is part of a two-way switching setup, hence the single cable, I suppose.

http://i.imgur.com/Ige9k.png

4) Proposed new cable layout. Roughly 40m required.

http://i.imgur.com/UqRlg.png

Note that from where the cable first appears in the attic would remain lengths of the original cable, joined somehow to new cable. That's so I don't have to run the cable all the way back downstairs to the hall light switch, which I think may be the next "junction".