Putting back an old metal wall sconce on a middle landing, that had been knocked loose, I made a point of connecting an earth (from the T&E) which didn't seem to have ever been connected. This made me a little unsure about the earthing of the circuit in general, and tracing the T&E back to a junction box, I discovered earth was not only not connected, but there was nothing to connect it to as the old twin cable feeding it had no earth. To complicate things further, the neutral was being borrowed from a neighbouring circuit, so the short twin cable from the switch was actually just a single live, from an old style dual switching circuit (thus the borrowed neutral).
Unfortunately the wiring going both up and downstairs is entirely embedded in the structure of the house, so pulling it out and putting in a proper 3&E modern dual switching circuit would involve major works, and I've checked the breakers and found that the same one is cutting both the circuit the neutral is borrowed from as well as the switch circuit in both positions, so it'll all have to stay there till the place is rewired. I'm just left with the problem of unearthed metal fittings.
So my question is: as there is a modern shower switch on the landing wall next to the light switch, is there any reason I shouldn't "Borrow" an earth from that, and just replace the short bit of cable from the switch to junction box with T&E (I've got some with the right colours), taking the earth to the junction box and from there to the metal fitting, and to another upstairs which is also earthed to the box with no connection ?
I know it would be preferable to rewire the whole thing, but given that isn't going to happen, are there any down sides to using the nice hefty recently fitted earth from the shower as an earthing point, or rather CPC to link back to the breakers and actually give some protection.
Yes I know I've switched between "Earth" and CPC, but you know what I mean.
Unfortunately the wiring going both up and downstairs is entirely embedded in the structure of the house, so pulling it out and putting in a proper 3&E modern dual switching circuit would involve major works, and I've checked the breakers and found that the same one is cutting both the circuit the neutral is borrowed from as well as the switch circuit in both positions, so it'll all have to stay there till the place is rewired. I'm just left with the problem of unearthed metal fittings.
So my question is: as there is a modern shower switch on the landing wall next to the light switch, is there any reason I shouldn't "Borrow" an earth from that, and just replace the short bit of cable from the switch to junction box with T&E (I've got some with the right colours), taking the earth to the junction box and from there to the metal fitting, and to another upstairs which is also earthed to the box with no connection ?
I know it would be preferable to rewire the whole thing, but given that isn't going to happen, are there any down sides to using the nice hefty recently fitted earth from the shower as an earthing point, or rather CPC to link back to the breakers and actually give some protection.
Yes I know I've switched between "Earth" and CPC, but you know what I mean.
