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UK diy (uk.d-i-y) For the discussion of all topics related to diy (do-it-yourself) in the UK. All levels of experience and proficency are welcome to join in to ask questions or offer solutions. |
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"Earth" floating at 80-120V ... why?
Hello
I noticed that a light switch back box measured around 100V ac w.r.t. the cold water tap in our recently-purchased house. I checked the earth bonding on the metal pipework for the hot and the cold tap and the radiator; all are at the same zero volt potential. I checked the earth of a nearby mains socket and saw no p.d. between it and the pipework mentioned. I looked around the house and I see lots of earth bonding that has been carried out within the last 3-4 years. Measuring a current flow to ground from this "dodgy" earth, I see a couple of hundred microamps flowing (actually about 275uA). Not enough to hurt but you can just about feel a "buzz" on your finger tip. I shall start trying to trace the lighting ring main back, but I am puzzled as to why this lighting ring earth should float when a nearby socket ring main earth doesn't. I am yet to carry out furthr investigations i.e. other looking at other ring circuits. Maybe this is a simple fix but I'd appreciate some guidance before I get up loads of floorboards etc. thanks in advance DDS |