LV Lights - notch joists or drill them?

[Winged Cat]

Following on from my post a couple of weeks ago about correct positioning of halogen lights, I now have a question about the cable.

I have two 80mm * 36mm ceiling joists to cross with the 5AMP round cable. The loft will be boarded with screwed down boards.

Do I drill something like an 8mm hole in the joists or do I notch from the top? The lighting circuit currently has notches cut out for the T+E in the top of each joist.

Thanks for you help.

[Ian Stirling]

The correct way is to drill the middle of the joist. However. Notching adjacent to an existing notch to the same depth will have almost zero effect to the strength of a beam. Keep it as close as you can, ideally just widen the notch.

[Winged Cat]

Thanks - I drilled the middle of the joist in the end which seemed to be the easiest solution after all. Didn't fancy the vibrations caused by hammering out fresh notches, what with my new ceiling just gone in.

[Dave Plowman (News)]

You cut across the joist with a saw to the depth required at either side, then tap out the waste with a sharp chisel. Being across the grain, the waste should snap out easily. If your ceiling can't survive this I'd be worried.