I was about to replace the two 2-way switches that control a ceiling light when I noticed that the mounting boxes are live - as indicated by touching with an electricians screwdriver! I would be grateful for any advice about this. Many thanks
switch mounting box
- Thread starter EMBEE
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I suspect there is no earth to the backbox
Thanks for that, although it seems odd that none of the other switches in the house respond in the same way to the tester screw driver. I will arrange for a check with a multimeter. Thanks againjj4091 said:
Thanks for responding. There are definitely green sleeved earth wires connected to the back of the box, but the mains tester screw driver lights up when they are touched [accepting that this is not a totally reliable test.RF Lighting said:
many thanks
There may well be an earth wire connected to the box, but I suspect there is no earth to the backbox.
The earth wire may not be connected to anything at the other end, or the entire lighting circuit may not have the earths connected.
The earth wire may not be connected to anything at the other end, or the entire lighting circuit may not have the earths connected.
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Are you confident with a DMM?
If so, what is the voltage between live & earth?
If so, what is the voltage between live & earth?
I'm not confident with DMM so have called in a qualified electrician who will come on wednesday. He suspects there probably is not a problem, other than the mains tester screwdriver, but I need to have peace of mind!securespark said:
Thanks for your suggestion
Maybe the screwdriver is lighting up due to an eddy current.Ive often put a screwdriver up to the earth or one of the cables in a twin brown T+E used for two way lighting switch and it has lit up .This wat ive been told so dont know if its true
RF Lighting said:
Sounds spot on to me, the earth is not connected at the other end and as it is running alongside the live wire a voltage is induced (will collapse if you try and draw any current). DMM will probably read a voltage as well.
Check the ceiling rose or junction box that the earth goes to to see if it is actually connected.
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stevesey said:
I agree. But not the full whack.
Yes, spot on! There was no earth connection on either switch, even though earth wires were connected at each switch. Earth wire now installed. Thanks to all!stevesey said:
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Do you know, I've come across that 3 times in as many months.
Light switch boxes that are connected to each other earthwise, but not to anything else.
In all 3 cases it's been two switch boxes at each end of a two-way circuit.
Very strange....
Light switch boxes that are connected to each other earthwise, but not to anything else.
In all 3 cases it's been two switch boxes at each end of a two-way circuit.
Very strange....
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These were all professional 60's installs where the feed comes in at one common as a single red & leaves the other common as another single red bound for the lampholder, and the only cpc was in the twin & earth used to strap the two together.
Nobody had thought at the time (probably due to earthing in lighting being in it's infancy) to bring an earth from the rose (although in the loop going round the house, a cpc was available).
Nobody had thought at the time (probably due to earthing in lighting being in it's infancy) to bring an earth from the rose (although in the loop going round the house, a cpc was available).
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