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Earth Wires And Electrical Safety
12 Answers
I recently rewired a table lamp and the process raised some questions.
1) If there is no place for the earth connection on a brass lampholder, could I solder the earth wire to any place on the body of it?
2) The lampholder includes two brass pillars which hold the switch in place. Could I attach the earth to one of those or might that mean it was ineffective if the switch was off?
3) If there is no indication on the lampholder where to connect live and neutral wires, does it matter which way round they go, taking the switch into account?
4) Once the job is done, is there any DIY version of the legally required safety tests for small electrical appliances?
1) If there is no place for the earth connection on a brass lampholder, could I solder the earth wire to any place on the body of it?
2) The lampholder includes two brass pillars which hold the switch in place. Could I attach the earth to one of those or might that mean it was ineffective if the switch was off?
3) If there is no indication on the lampholder where to connect live and neutral wires, does it matter which way round they go, taking the switch into account?
4) Once the job is done, is there any DIY version of the legally required safety tests for small electrical appliances?
Answers
1 to 12 of 12
As with any metal-bodied fitting, Chiefy, it must be earthed, and have a 3-core cable. (2-cores are for "double insulated" fittings which don't need an earth.) I wouldn't earth with the switch pillars for the very reason you mentioned. Solder to the lampholder by all means. A mechanical connection by drilling and self-tapping screw would also be fine. As...
14:30 Wed 23rd Jul 2014
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1) Go out and buy a brass lampholder that has an earth wire screw terminal on the body of it.
2) Can't visualise what you mean, but after 1) it should be irrelevant.
3) While the lamp will still work whichever way round the wires are connected, the preference would be for the brown (live) wire to be connected to the cable's plug side of the switch. That way, with the switch in the 'off' position, you wouldn't get a shock if you stuck your fingers into the lampholder.
4) Not really. Electricians have to pay a lot for PAT testers, which aren't aimed at the DIY market.
2) Can't visualise what you mean, but after 1) it should be irrelevant.
3) While the lamp will still work whichever way round the wires are connected, the preference would be for the brown (live) wire to be connected to the cable's plug side of the switch. That way, with the switch in the 'off' position, you wouldn't get a shock if you stuck your fingers into the lampholder.
4) Not really. Electricians have to pay a lot for PAT testers, which aren't aimed at the DIY market.
As with any metal-bodied fitting, Chiefy, it must be earthed, and have a 3-core cable. (2-cores are for "double insulated" fittings which don't need an earth.)
I wouldn't earth with the switch pillars for the very reason you mentioned. Solder to the lampholder by all means. A mechanical connection by drilling and self-tapping screw would also be fine.
As for polarity... not important with conventional bayonet fittings which,I guess, yours is. Only matters with ES (Edison Screw) bulbs where the "live" should connect to the pointy bit of the bulb, and the neutral to the screw bit.
PAT testing (Portable Appliance Testing) has to be done by someone competent. Some simple Earth continuity and Insulation Resistance tests primarily. If you have the meters, and know how to use them, you could satisfy yourself, but any electrician, or maybe a shop, can do it for a few pounds.
I wouldn't earth with the switch pillars for the very reason you mentioned. Solder to the lampholder by all means. A mechanical connection by drilling and self-tapping screw would also be fine.
As for polarity... not important with conventional bayonet fittings which,I guess, yours is. Only matters with ES (Edison Screw) bulbs where the "live" should connect to the pointy bit of the bulb, and the neutral to the screw bit.
PAT testing (Portable Appliance Testing) has to be done by someone competent. Some simple Earth continuity and Insulation Resistance tests primarily. If you have the meters, and know how to use them, you could satisfy yourself, but any electrician, or maybe a shop, can do it for a few pounds.
Anyone who needs to ask this question should not be undertaking the job.
Be aware that a PAT meter test is NOT the last word. I have long made a habit of casually looking over electrical goods at Op shops in the town where I live.
I saw a lamp at the Salvation Army shop that had been fitted with a test certificate. Yes it passed the insulation resistance meter test but it should have failed on the visual inspection.
It had been a double insulated but someone had replaced the part of the wiring in a metal clad flexible section with speaker wire. Very, very dangerous.
Be aware that a PAT meter test is NOT the last word. I have long made a habit of casually looking over electrical goods at Op shops in the town where I live.
I saw a lamp at the Salvation Army shop that had been fitted with a test certificate. Yes it passed the insulation resistance meter test but it should have failed on the visual inspection.
It had been a double insulated but someone had replaced the part of the wiring in a metal clad flexible section with speaker wire. Very, very dangerous.
Well, I'm impressed by the firepower this site can bring to the question. Thanks for it.
Methyl is right to guess the old cables were two-core and I was tempted to simply copy, as I had some nice old silk-wound flex, but I guess attitudes to risk have changed. I too am surprised to hear that Anglepoises were wired the same way. I suppose that was with what The Builder calls double-insulated fittings, which I take to mean those with plastic around the outside as well as around the actual power-supply pins.
Heathfield and Beso suggest I shouldn't be even trying to do my own PAT tests if I need to take online advice. Fair dos, although it would be a dull world in which a fella can't repair his own table lamps. However, I might try to get a shop to do a PAT test, just to see how easy it is and how much it costs Will let you know.
Meanwhile, thanks for the guidance.
Methyl is right to guess the old cables were two-core and I was tempted to simply copy, as I had some nice old silk-wound flex, but I guess attitudes to risk have changed. I too am surprised to hear that Anglepoises were wired the same way. I suppose that was with what The Builder calls double-insulated fittings, which I take to mean those with plastic around the outside as well as around the actual power-supply pins.
Heathfield and Beso suggest I shouldn't be even trying to do my own PAT tests if I need to take online advice. Fair dos, although it would be a dull world in which a fella can't repair his own table lamps. However, I might try to get a shop to do a PAT test, just to see how easy it is and how much it costs Will let you know.
Meanwhile, thanks for the guidance.
/I saw a lamp at the Salvation Army shop that had been fitted with a test certificate/. One of the drawbacks is that anyone can go out and buy a packet of PAT test stickers.
/Heathfield and Beso suggest I shouldn't be even trying to do my own PAT tests if I need to take online advice./. I wasn't suggesting that, Chiefy. Just that PAT testers aren't normally found amongst DIYers. If you could borrow one, then you might just as well have its owner to do the test for you.
/Heathfield and Beso suggest I shouldn't be even trying to do my own PAT tests if I need to take online advice./. I wasn't suggesting that, Chiefy. Just that PAT testers aren't normally found amongst DIYers. If you could borrow one, then you might just as well have its owner to do the test for you.
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