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Electrical

Joists - notched in the middle of their span

Hi guys,
just had an electrician install new sockets - but he has notched the joists, all along a room - and in the very centre of their span.
I think that is not to specs - there are regs on where you can notch and the centre of the beam's span seems the worst spot possible. The notch is appprox 1.5 cm so is below 1/8th of the joist height. But still.
I am concerned that these same joists were already notched for central heating and are quite bouncy.
Your opinion?
--- turns out the notches were quite old, the electrician reused them rather than make further holes ---

1 Answer from a MyBuilder Electrician

Best Answer

If notched into the joist cables are required to be provided with mechanical protection sufficient to prevent penetration of the cable by nails, screws and the like (NOTE: the requirement to prevent penetration is difficult to meet)
Maximum depth of notch should be 0.125x joist depth. In a zone between 0.07 and 0.25 of joist span.
Normal practice is to drill holes max 0.25 x joist depth at least 50mm from top and bottom. In a zone between 0.25 and 0.4 of joist span.

2019-12-01T11:50:37+00:00

Answered 1st Dec 2019

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