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Junction box depth

RustyH

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? 

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  • 0

    Thanks, I actually hadn't thought about the loft boarding situation, although it has 300mm.of loft insulation, so would have to be on stilts anyway.

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

    Is the most common still at the ceiling rose (where pendants are fitted), or are most switching to looping at the switch now? Do many loop at Maintenance Free boxes, so only a. Single 2 cores cables drop to the switch and single 2 core off to the light point? (especially as most modern lights these days done have terminal to loop at them, so option 1 is dying out a bit) 

  • 0 in reply to RustyH

    I loop switch to switch so that a neutral is available at the switch. The more points of connection you have spread around under floors and in lofts, the higher the number of points of potential failure you are introducing, plus some accessories won't work with out a neutral at the switch position. For retrofitting downlights to an existing loop-in system I use wago boxs or J804s.

  • 0 in reply to whjohnson

    Yep, loop at the switch positions. That is sensible, and a neutral available if needed in the future. Perhaps a deeper box than usual at the light switch positions as well.

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  • 0 in reply to whjohnson

    Yep, loop at the switch positions. That is sensible, and a neutral available if needed in the future. Perhaps a deeper box than usual at the light switch positions as well.

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