Hello all, the las cct I'm putting in is the upstairs lighting. this will have to run through insulation as the specs require me to run quilted insulation in two layers at right angles. I will derate the lighting cable, but will it be OK to derate to 2.5mm, might be an overkill but i have some left over and it would save me buying 1.5mm
Cheers
If you are using 1mm cable on a 6A MCB, it is already redated by about 50% and no further derating is required. You can use thicker cable if you want to, but it might be harder to get the conductors into some lighting accessories.
Try to run the cable on one side of the insulation (either above or below) rather than through the middle, although at 50% or more derated, you can theoretically run it through the middle.
Use this calculator to find out what's needed. 2.5mm might be awkward to terminate in some lighting fittings.
Nice one, thanks.
I will only be drawing 200watts off it so not even an amp !! I'll just use 1mm then, there will be 2.5m which will have to run in insulation unless I suspend it on the trusses above and then drop it down, is this OK, are there any regs as to running cables in roof spaces?
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