Running cables through boxes

I have quite routinely done tthis - actually I have put back boxes and cover plate on a wall to serve no purpose other than to reveal a route, and make a buried cable then be in a 'safe zone'. In effect the back box becomes rather  like an inspection elbow would be for conduit.


It is very rare you need to take a box out of the middle of a run and if you do, either split the box (tin snips to slot and bend out a section from the front to the holes, then tuck the cable behind and reflatten the box)  or cut and rejoin the cable.

But normally a box change implies some catastrophic event requiring new cables anyway.

The bigger barrier is that the box gets too full if say there is a single socket too, but no regs related objections.


I now await a storm of folk telling me this is wrong and why   ?

We used to run cables of many different circuits through large steel adaptable boxes in metal conduit installations. That is normal practice.


Go for it, whatever type of cable, singles or T&E. Perhaps a warning label may be required if there is any doubt about some circuits still being alive when others are disconnected by the circuit protective device if you prefer. Similar to 514.15.1.


Z.

I have seen a prohibition on running cables through boxes not served by those cables, in some client specifications. This may have given the impression that the practice is forbidden by regulations, rather than simply being contrary to some job specs.

MHRestorations:

... imagine a row of sockets on an RFC... his method would have you cutting the cables at each box and jointing them?

It's not very economical use of cable (radial would be better) but I have that (cables running through boxes, not jointed) in my workshops at home - surface mounted boxes and mini-trucking. Perhaps your chum would allow this situation because they are limbs of the same circuit?

 

... not proper surface conduit work, where he agreed that no cutting would be necessary as you can unthread and rethread the cables

Unthreading might be OK, but retreading could be a bit of a challenge. In these circumstances, I don't understand why you would want to remove a box. ?

There could be something related to the bad old practise of running cables through luminaires to other fittings. A real pain if you need to change the fitting.

Yes - I'd agree that is not a great practice, but it is not forbidden. And actually my expectation, to solve that issue, is the wires going through a box behind or beside the light fitting, in an arrangement rather like the ceiling rose but with a junction box instead. (or an appelby or similar.)

Yes - I'd agree that is not a great practice, but it is not forbidden.

Actually, for luminaires, it is forbidden (unless the fitting is specifically designed for through wiring) - reg 559.5.3.1.


  - Andy.

Thanks for the responses, it's likely that it's just how he was trained? With regard to the running through light fixtures... that came up on our 18th edition course,  the manufacturer's directions will state if it's acceptable to through wire, but I'm with zoomup, if there're holes both ends... it's obviously envisaged.


Any wiring through a fixture though, imo, should be directly related to that particular row of fixtures, to avoid the issue of having to replace a middle of a run fixture. Although these days with wago's being so reliable and 'maintenance free'... It's not insurmountable.


I admit I don't like running ANOTHER circuit through an accessory box, unless it's unavoidable, and labelled. ('can you add undercabinet lights', after the tiling's been done in a kitchen, is a prime example). The conduits we ran in for the ring final running to the FCU above the extractor hood are often the only place to run a 1.0mm for them! (in that case we usually spur them off the ring with a 3A in an FCU so they ARE technically on the same final circuit)