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Junction box depth

Evening All, 

I typically wire lighting circuits with Hager JBs close. To the light switch drops, and I guess I have been lucky enough not to have come across thin loft joists before to ask this. 

I'm working on a house at the moment where the loft joists are thinner then I have seen, such they are equal to or slightly shorter than the Hager Junctions boxes I like to use, meaning the JBs would rest against the ceiling and protrude above the joist 

I can't point to a Reg that defines any requirements on this, so is that acceptable or would it be better to travel a few meters away from the switch drop to the joist binder beam that sits above the joists? 

  • While on the subject and in regards to WHjohnsons comment, what are most peoples preferences these days to creating the loops.

    On the recommendation of this forum, I have tried looping at the switch, but the box can become terribly crowded, especially with 2-way switching - e.g. entrance hall with one switch for upstairs, one for downstairs, and one for the front porch. So I am not terribly keen on that.

    The answer really is to be familiar with all varieties, but in an ordinary house and starting from scratch, my preference is for junction boxes (MF these days) because they are simplest.

  • I don't see a problem. It's better that it's accessible than not. It would generally be below the insulation if pushed back up through a down light hole. 

    Gary