A friend of mine has recently moved house and asked me to have a look at the wiring to the light in his attached garage, which is in surface mounted T&E. When he opened up the light fitting to replace it with a new one, he discovered that inside, in addition to the cables being used to supply the light, there are also some singles, which disappear through the cavity house wall. Their ends were all in separate screw terminals wrapped in insulation tape.
Investigation of these 'singles' revealed that there is a single red, live supply + earth supplied from the circuit fed by the MCB for the house downstairs lights. Between the switch and the light, there is a second red 'single & earth' which will be the switched live. Also at the light fitting, as expected, there is a black single. Here's a sketch of the set up.
Testing the cables for insulation & continuity reveals that all is well with the live side of the original wiring, however, the black is not connected to a neutral, or anything else as far as I can tell. (no continuity between it and neutral and no voltage present between it and live, or it and neutral)
So it looks as if the neutral has been lost at some point and new wiring installed with the original singles left in situ.
I have not been able to detect the presence of said cables inside the house using a metal detector, so I suspect they run inside the cavity. [The cables from the consumer unit certainly do, but inside a clay pipe] The presence of the staircase behind the light makes checking this difficult.
There are no singles visible at the consumer unit, and it would appear that the wiring uses junction boxes, because the adjacent lights are not 'loop in' as only a single T&E can be found at each light switch and fitting. We've not been able to find any of the junction boxes though. Having recently moved in and had new flooring installed throughout, there is an obvious reluctance to start ripping it all up again.
The previous occupants were there for about 10 years and say the wiring wasn't changed by them.
My friend has asked me what he should do about it & I'm not sure what to recommend. Suggestions welcome.
Investigation of these 'singles' revealed that there is a single red, live supply + earth supplied from the circuit fed by the MCB for the house downstairs lights. Between the switch and the light, there is a second red 'single & earth' which will be the switched live. Also at the light fitting, as expected, there is a black single. Here's a sketch of the set up.
Testing the cables for insulation & continuity reveals that all is well with the live side of the original wiring, however, the black is not connected to a neutral, or anything else as far as I can tell. (no continuity between it and neutral and no voltage present between it and live, or it and neutral)
So it looks as if the neutral has been lost at some point and new wiring installed with the original singles left in situ.
I have not been able to detect the presence of said cables inside the house using a metal detector, so I suspect they run inside the cavity. [The cables from the consumer unit certainly do, but inside a clay pipe] The presence of the staircase behind the light makes checking this difficult.
There are no singles visible at the consumer unit, and it would appear that the wiring uses junction boxes, because the adjacent lights are not 'loop in' as only a single T&E can be found at each light switch and fitting. We've not been able to find any of the junction boxes though. Having recently moved in and had new flooring installed throughout, there is an obvious reluctance to start ripping it all up again.
The previous occupants were there for about 10 years and say the wiring wasn't changed by them.
My friend has asked me what he should do about it & I'm not sure what to recommend. Suggestions welcome.
