Junction box ok under insulation in loft?

[nellystew]

I want to move the position of the light fitting in one of my bedrooms.

I'm going to extend the current cable using a Quickwire MF 2-way splitter, I'll mount it to the side of the joist but will it be ok under the insulation?
It's a new build and there's a lot of it.

 

[flameport]

If this is the usual 6 amp lighting circuit wired in 1.0mm² or 1.5mm² then OK for the box under the insulation and so is the cable.