Cables in Attics

[baza]

Hi Guys
Can anyone point me to the regulations for running cables in attics, or what do you guys do in practice, I am unsure whether cables should be run free or clipped to joists

 

[Adam W]

Either is fine, provided not covered by the insulation. I prefer to clip direct to the joists wherever possible because it looks neater and keeps the cables out of the way of anyone going in the loft.

 

[DurhamSparky]

do what most people do!! chuck them up there and then pack it full of crap for xmas then trample them to crap when you go up there...!!

would they do that to gas pipes!!



clipped as already mentioned looks better!!

 

[Andyfm]

I thought they have to be clipped out of harms way wherever people are likely to walk or move stuff about - preferably to the side of joists, this also stop them being surrounded on all sides by insulation

 

[Deleted member 9648]

There are no specific regulations for cables in attics,general rules for protection from mechanical /thermal/vermin damage apply.The regs state that wherever practical a cable should be fixed in a position where it will not be covered by thermal insulation,if it is it must be de-rated accordingly...ref method 100-103 of table 4A2.
Where a job will stand the extra time and expense I use running boards of say 6x2 battens fixed above the level of insulation for main runs and try to plan the wiring to keep as much as possible on these boards.

 

[dichroic]

Cables in lofts and other accessible voids should not be installed over joists (supporting the ceiling below) or over the low-level parts of roof trusses, except:

In areas of the void where the cables will not be susceptible to mechanical damage, and where the cables are provided with adequate protection against mechanical damage.

It should be borne in mind that the joists etc in lofts and other accessible voids are prone to being walked on (for example by persons using the space for storage or to gain access to water tanks), and to having objects placed upon or moved across them (such as stored items or loose-laid boards). It is therefore necessary for cables to be positioned or protected so that they will not be damaged by adverse influences such as impact, penetration, abrasion, crushing or pulling.

Regards

Dichroic

 

[Naz]

Look in building regs for specifics, Part P will give you stuff like holes through joist, max size of holes, distance from walls etc,

 

[ezzzekiel]

I tend to clip cable along top edge of joist to keep it up out of insulation (thats top of side not on top)

 

[martysparky]

you could nail a board to the A frame and run along that then just short runs along the sides of joists to keep as much above insulation for future non aware peoples moving things around in loft.

oh and for when the insulation people come in with extra insulation and there flower pots.

 

[ringer]

I tend to clip cable along top edge of joist to keep it up out of insulation (thats top of side not on top)

The insulation depth in most people's lofts may be 50mm but have you seen how thick the recommended depth of loft insulation is these days?
270mm
Now unless the joists are 12" deep any cables clipped to the sides are going to be covered by insulation to the current recommendations. Customers need to be warned about effects on cables if they are in future covered by extra insulation.

 

[martysparky]

the answer I was told was to move or make void in the insulation for cable but the insulation technicians don't seem to worry about it and that would not stop it being covered with the traffic and stuff being pilled in the loft.

I think, as it is preferable to arrange cables so they are not totally enclosed over 5cm the only real answer and safest option would be to enclose cables in a rigid void / barrier that runs the whole length of the joist so air can pass through.

Something like a narrow cable tray with a hinged lid that could be simply screwed in place would be ideal.

 

[ezzzekiel]

The insulation depth in most people's lofts may be 50mm but have you seen how thick the recommended depth of loft insulation is these days?
270mm
Now unless the joists are 12" deep any cables clipped to the sides are going to be covered by insulation to the current recommendations. Customers need to be warned about effects on cables if they are in future covered by extra insulation.

providing cables are not covered with insulation when installed then you have complied, if some numpty comes along later and covers them.......

besides which an upstairs lighting circuit will usually be very lightly loaded typically 100w per room so even after applying correction factors chances are 1.5mm would be sufficient (obviously depending on each individual property loading)

 

[EasT]

When I laid extra insulation I raised the Cooker, Immersion cables above and also the 13 amp cables for much of their length. The lighting cables I buried. I have 150 mm of insulation in loft. As I live in a solid floor bungalow all cables run in the loft. and 150 on outsides.

 

[martysparky]

providing cables are not covered with insulation when installed then you have complied, if some numpty comes along later and covers them.......

besides which an upstairs lighting circuit will usually be very lightly loaded typically 100w per room so even after applying correction factors chances are 1.5mm would be sufficient (obviously depending on each individual property loading)

how about the shower

above and drop through yeah

I've seen so many houses with insulation top ups with a shower cable unclipped running free between layers of thermal insulation. the same goes for lighting circuits. its wonderful

 

[martysparky]

providing cables are not covered with insulation when installed then you have complied, if some numpty comes along later and covers them.......
)

we knew that might happen and took the chance...common practice I know