Domestic wiring question of the day
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Yeah, I got a 40 seconds blast through the chest when I was 6. Wasn't much fun actually and it burnt a hole right to the bone in my right hand. They grafted skin from the back of my then hairless fingers over it with the consequence that I now have a hairy part of my palm-cum-finger. Nice one NHS. Having said that, I don't know where to find skin without any hair, soles of the feet maybe.
Regards, Rob Philpott.
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Unless you're a Hobbit!
They had hairy feet! You get hairy palms...um...another way... :-O
Those who fail to learn history are doomed to repeat it. --- George Santayana (December 16, 1863 – September 26, 1952) Those who fail to clear history are doomed to explain it. --- OriginalGriff (February 24, 1959 – ∞)
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Sounds like you have a floating earth and it definitely needs to be fixed. You could be picking up voltage through inductance or there is an earth fault developing on a piece of equipment somewhere. Hopefully you have a functioning ELCB at the main incomer which is at the current legislative requirements (UK) of 30mA, so if things do get worse you have some protection. Time to get a sparky in.
DaveAuld wrote:
Hopefully you have a functioning ELCB at the main incomer which is at the current legislative requirements (UK) of 30mA, so if things do get worse you have some protection.
Thank elephant for decent safety legislation - I know we all knock 'elf & safety, but having lived in a place where the [rare] actual standards are flouted I'm glad we have them & they are adhered to. Over in the middle east the "electrician" we had in extended the cable to the portable electric heater - he wired a existing 13a three-core cord to the sort of two-core cable commonly used for doorbells. He didn't even use a junction box - just electrician's tape - double plus good when the cable was run across the floor with children running around. I wired up a proper extension cable - when I found out, and I only noticed it something was wrong because when I trod on the doorbell cable it was warm underfoot... I blame the "it is written" mentality in the Middle East - it took some convincing that just leaving this to chance was not a good idea, especially in a tinder-dry room.
Alberto Brandolini:
The amount of energy necessary to refute bullshit is an order of magnitude bigger than to produce it.
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Also - when testing a circuit that may be live, put your left hand in your back pocket. That way any electricity will not have a path across your heart. You use your back pocket because a large shock will cause your hands to clench....and you don't want that to happen in your front pocket :-)
A guy I once worked with had been a sparks in the Royal Navy until invalided out with a condition not related to electricity zapping! According to him the way to test if a circuit was live was to touch your fingers to it, but you had to make sure that you used the backs of your fingers. Using the pads of your fingers could lead to the involuntary muscle contractions making your hands grab on to the cable. Using the backs of your fingers caused them to pull away when the muscles went into spasm!
========================================================= I'm an optoholic - my glass is always half full of vodka. =========================================================
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So, in my old house you could get a small 'shock', although that's probably a strong word for it from touching the metal light switches. It would be most noticeable if you gently stroked the switch (there are worse perversions) as a sort of fuzziness in your fingertips. One of those electrical tester screwdrivers lights up when you touch it. Said light switches were earthed, but I guess it means the earth wire wasn't actually attached to the Earth and was floating. My questions is where the electricity came from. I was thinking a short via a very high resistance somewhere but then I actually wondered whether it could be caused by induction, the wiring in the house acting as a very spread-out transformer as such. Any thoughts from the electrically minded?
Regards, Rob Philpott.
It is probably stray capacitance that's giving you a small leakage current. However, as others have said, it's a symptom of a potentially serious fault and you need to get a professional to look into and rectify the problem, and the sooner the better. If indeed there is no main earth connection, but you have appliances with metal cases that are connected to the (floating) earth, then a second fault in one of those appliances could make the cases of all of them live. The consequences of that would not be good.
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No, not really. What it means is that your earth is not connected. pretty much anywhere, but certainly in your lighting circuit. Which means your appliances aren't earthed either, most likely. Since this isn't tripping your RCD (which has earth leakage detection and should shut down if any live reaches the earth) that probably means you don't have one. So an "good" electrical fault could leave the casing of your washing machine live, for example. Or start a fire. Or hurt children or the elderly. This is not a good thing.
Those who fail to learn history are doomed to repeat it. --- George Santayana (December 16, 1863 – September 26, 1952) Those who fail to clear history are doomed to explain it. --- OriginalGriff (February 24, 1959 – ∞)
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OriginalGriff wrote:
Or hurt children or the elderly.
This is not a good thing.Nope. Still failing to see the downside.
Some people love their children. (Presumably because they still have the receipt and they are still in warranty) And many old folk can afford good lawyers.
Those who fail to learn history are doomed to repeat it. --- George Santayana (December 16, 1863 – September 26, 1952) Those who fail to clear history are doomed to explain it. --- OriginalGriff (February 24, 1959 – ∞)
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So, in my old house you could get a small 'shock', although that's probably a strong word for it from touching the metal light switches. It would be most noticeable if you gently stroked the switch (there are worse perversions) as a sort of fuzziness in your fingertips. One of those electrical tester screwdrivers lights up when you touch it. Said light switches were earthed, but I guess it means the earth wire wasn't actually attached to the Earth and was floating. My questions is where the electricity came from. I was thinking a short via a very high resistance somewhere but then I actually wondered whether it could be caused by induction, the wiring in the house acting as a very spread-out transformer as such. Any thoughts from the electrically minded?
Regards, Rob Philpott.
BarrRobot is right sir. Many appliances (washmachines, computers, microwave oven...) have Pi filters with small capacitances linked to the metal case that make an voltage leakage on cases when earth (plug) is not realy earthed (grounded) from main power supply. The actual leakage current may be not sufficient to make protection effective (30mA min.)! You must connect ( if not) an additional earth (ground) fault protection device to the earthed (grounded) connectors. Any case, the electrical system has to be earthed and that it have to comply with safety standards.
entia non sunt multiplicanda praeter necessitatem
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BarrRobot is right sir. Many appliances (washmachines, computers, microwave oven...) have Pi filters with small capacitances linked to the metal case that make an voltage leakage on cases when earth (plug) is not realy earthed (grounded) from main power supply. The actual leakage current may be not sufficient to make protection effective (30mA min.)! You must connect ( if not) an additional earth (ground) fault protection device to the earthed (grounded) connectors. Any case, the electrical system has to be earthed and that it have to comply with safety standards.
entia non sunt multiplicanda praeter necessitatem
I hope I'm right - I'm a Chartered Electrical Engineer! I can think of a relatively simple test to establish whether there is indeed a missing earth connection, but the test itself would involve an element of risk. As there is a strong indication that the installation is not compliant with the safety standards, professional help is the only course of action that I'd normally recommend.
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So...you are admitting to having "hairy palms" and blaming it on "Electricity"? :laugh:
Those who fail to learn history are doomed to repeat it. --- George Santayana (December 16, 1863 – September 26, 1952) Those who fail to clear history are doomed to explain it. --- OriginalGriff (February 24, 1959 – ∞)
Not so - I take Gentlemen's grooming very seriously. No hair there, nostrils or ears, although regular remedial action is required.
Regards, Rob Philpott.
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So, in my old house you could get a small 'shock', although that's probably a strong word for it from touching the metal light switches. It would be most noticeable if you gently stroked the switch (there are worse perversions) as a sort of fuzziness in your fingertips. One of those electrical tester screwdrivers lights up when you touch it. Said light switches were earthed, but I guess it means the earth wire wasn't actually attached to the Earth and was floating. My questions is where the electricity came from. I was thinking a short via a very high resistance somewhere but then I actually wondered whether it could be caused by induction, the wiring in the house acting as a very spread-out transformer as such. Any thoughts from the electrically minded?
Regards, Rob Philpott.
If you are familiar with the current regs and have the correct equipment by all means trace the fault and fix it yourself . Failing that , and recognising that because you do not know the cause then it could potentially lead to electrocution ( which tends to be a bit ouchy if your lucky or a bit deathy like if your not) Then I would get someone who does know the regs and does have the equipment . I believe they are called professionals . Just imagine this as the coding VB6 to control an aircraft whilst you are on the aircraft . It might work , there might be no issues , but ? Really ?
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Well, it's been like that for four years. I just started using plastic light switches in the end. Clever huh?
Regards, Rob Philpott.
