pvc trunking run under loft insulation

[bradder]

was asked this question the other day :-If cables are run in pvc trunking under fibre glass in a loft would the Reference method change ie from B (trunking on a wall) to possibly A (in a thermally insulated wall)?
if not , what reference method would you go for ?
Existing cables in the loft are bunched together and run under fibre glass.

 

[MarkieSparkie]

What types of cable are being run in the trunking?

 

[Richard Burns]

If the existing cables are run on top of the ceiling but under fibreglass (presumably insulation) then this would be method 100 or 101. If the cables are then placed in trunking on top of the ceiling and the trunking covered in fibreglass I think this would then be method A.
You would have a similar thermal transfer effect to conduit in an insulated wall. There would be a reduction in heat loss through the insulation so could not be classed as B, but no significant change in heat loss by placing it in trunking rather than directly under insulation, so if the fibreglass is over 100mm then probably best to stick with 101.

 

[telectrix]

or remove insulation from directly over the cables. sssimples.

 

[bradder]

pvc twin and earth cables

 

[bradder]

thanks for the reply's ,
was thinking along the lines of reference method A