I have a a 4-way light switch in one room which I would like to move to the hall. I can't easily access rose connections as they are all over the place so fully replacing switch cables is not an easy option.
I've considered extending the existing cables back up the wall using 1.5mm, running across the top in the safe zone and into the hall, then back down. I was then going to move the existing light switch out into the hall, and splice the cables in the old switch backplate using connection blocks. I'd then cover the old back plate with a blank panel.
Is this a reasonable, compliant, and safe approach? My concerns were with (1) this approach to splicing and (2) with running six cables next to each other back up the wall due to any derating, heat, etc concerns. (I cannot figure out the IEE site guide with regards to this)
So what you are doing is joining the cable within the existing back box for a four gang switch and fitting a blankplate over this box? Then extending cables from this box, within the permitted safe zones, to the hallway, then installing the switch there. Should be no issue with cable grouping, but because you are installing new cable to the circuit, which will be buried in the wall (less than 50mm), then 30mA RCD protection will be required for at least this part of the circuit, or the use of mechanical protection, unless this protection is already offered upstream on the circuit, such as at the consumer unit.
Exactly what you said - leaving everything as-is, but extending the cable run to the new location of the light switch, in safe zones. The cables will run primarily in dry wall; and be spliced in the existing back box (will sit behind a free-standing bookcase)
The property is new build so RCDs are in place - although if they are 30mA on this circuit or not I will need to check. I assume that requirement would be to make any new installation of conductor comply with current regs if an RCD were not already in place (?)
One question - is fire-proofing putty required in plastic back boxes..?
Generally I would say that if the CU was new that RCD protection existed, and chance are that it will be 30mA, this normally viable on the RCCB unit, will say something like "IΔN 0.3A" on it. To make sure the circuit is protected by RCD press test button on RCCB, if circuit loses power than it's covered. Then reset to power back up.
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