L.V. and E.L.V, cables running together.

It only becomes a real problem in terms of safety,  if the outer jacket on the T and E were missing - then it would be LV and ELV sharing containment, and if the insulation on the bell wire has to be neglected for the mains purposes, then it becomes single fault to danger. With the T and E jacketed, it is more like singles in a (thin) plastic conduit, which we would consider adequate segregation.

From an EMC perspective it still  is not a good idea to run cables that feed electronics next to mains wiring. An old fashioned coil hammer and bell is unlikely to be affected, but a modern synthesised electronic unit perhaps with a radio link, that plays 'Colonel Bogey' or whatever may not be as tolerant of spike when the fridge kicks in.

I doubt that is a big issue in practice, but strictly speaking, if LV and ELV cables are to share the same containment, then BOTH must be insulated for the highest voltage present.

If the bell wire shown is only ELV insulated, then it should not be in the same containment as the mains voltage cables.


Had the bell circuit been wired in mains rated cable, then I see no problem. I have used 300/500 volt 0.5mm flex to wire bell circuits and consider this to be acceptable in the same enclosure as mains power cables.


My personal view is that the requirements are unduly onerous. If the insulated and sheathed mains cables are safe to touch, then in MY VIEW they are safe in contact with single insulated bell wire. However my personal view does not override the requirements for ALL cables to be insulated for the highest voltage present.

Combined power and data SWA


Andy Betteridge

That EV plus cable is a nice idea for the work at home office in a garden summer house idea as well, telephone and power in the same trench. I can imagine that preserving the separation at the terminations could  be quite fun though, as well as getting enough shielding for EMC purposes. Box in box perhaps.

Also puts power over ethernet in its proper place.