running cables in lofts/roofspaces

[trefolex]

What is everybodys thoughts on how to avoid cables touching insulation in lofts,while securely fixing them to avoid trip hazards.During a recent bungalow rewire that a couple of collegues did,this was achieved by running everything in mini trunkings at the request of management.I don't know if this is a recent niceic stipulation,although that is the message that seems to be doing the rounds.I would like to know other peoples thoughts on this.cheers.

 

[spark1]

Providing that cables are clipped to the side of a joist then the fact that they are touching insulation will not have an adverse effect on their current carrying capacity,,,assuming that is what you are concerned about.
Have not heard of practice of enclosing them in mini-trunking in loft spaces....would the trunking be supported above the insulation ? if not then I think the cables current carrying capacity will be further affected by this as the cables will be less able to loose heat due to being enclosed in the mini-trunking thereby making the situation worse rather than ,as is intended, better !


spark1

 

[trefolex]

Thanks for the reply and for echoing my views.What they are asking us to do is fully enclose the cables in trunking and run it under the insulation,or if not practical,run it so it isn't a tripping hazard.They say that it is being talked about on the internet but i can't find anything about it.Is their a nic forum,maybe thats where it is being mentioned?.I F IT IS TRUE THEN GOD HELP US.cheers.

 

[pushrod]

agree with spark1 - to reduce a possible trip hazard i would just reduce the cable clip spacing slightly

 

[trefolex]

They are talking about getting a labourer to remove all insulation prior to a rewire or major cabling job,then reinstating it after.Totally agree with spark 1,s reply about heat dissipation and adequacy of just clipping cables.I mentioned this during a conversation with gaffer but he told me that they have not got to touch insulation at all.It is as though somebody has misinterpruted a regulation along the lines,and others are following.

 

[spark1]

Ask your gaffer how he thinks all new build properties are wired if cables cant touch insulation.....these properties are full of the stuff !. Ask him to look in the regs page 282 and there he will find the necessary acceptable installation method and current carrying capacities for exactly this situation.


spark 1

 

[trefolex]

Cheers spark1,have you got any idea where this bull is being discussed ie other forums etc,in 30 years of running cables like we have mentioned or seeing them run this way,i have never come across a problem.Why change now?.

 

[spark1]

As I said Ive not heard anything like this mate.

If he insists on you installing the circuits this way make sure he signs for the design part of the E.i.c.
There is quite a large overdesign on 1mm2 for 6A lighting circuits so even after derating the cable it will probably still comply even in this unusual installation method.Just wondering if as you state ,it is a bungalow, are the sockets wired through the loft? if so I would tell him to definately do the cable calcs
as 2.5mm2 has to be able to carry 20A. in its installed method of installation.also what about Cooker Or shower circuits ?




spark1

 

[trefolex]

Yes everything run in loft,solid floors.Wish i could find where he as seen this,i will ask him next week.cheers.

 

[spark1]

Let us know how you get on.

Clocking off now.......have a Nice Easter !


spark1

 

[scotsparky]

Ho about hammering a bit of 4 ' plank along the eaves of thou house and clipping onto that . Its above the insulation and not a trip hazzard.

 

[trefolex]

and you mate.cheers.

 

[Guest123]

Hi.

I'd agree with whats been said about the trunking issue under the insulation, but have seen it done before.

As long as they are clipped direct to a timber on one side all should be fine. The only cables I do run above the insulation is a shower cable, sub-main cable, and usually the cooker cable also.

I have piped an attic in galv before now, but that was due to a rodent infestation. All the pipe was above any insulation and we used singles for the wireing system.

 

[chippysparks]

My gov' has just had the NIC man in, and he was talking about something along these lines, and the cables have to be touching the plater bord or enclosed, something like that anyway.

Im not entirely sure, im still doing things as a alwayse have, untill he pulls me up.

 

[spark1]

Hi ChippySparks, as I explained last week, providing the cables are clipped to the sides of the joists or in direct contact with the plasterboard ceiling then there will be no problem. The fact that the loft insulation is touching the cable has no detrimental effect as far as the life of cable insulation is concerned...therefore I dont see the point in enclosing it in trunking.
When you say the NIC man is this an NICEIC Inspector or an NICEIC Contractor ?


spark1