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Checking Appliance Earthing.

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Today I spoke to the manager of a local chain of domestic appliance retail shops. The chain sells and installs appliances like cookers and ovens etc. I asked the manager if they carry out an earth fault loop impedance test to confirm adequate earthing of the supply circuits and good earthing of appliances like cookers. He said that they did not. He asked me what test gear is used to carry  out the tests. I was shocked by this. People are having appliances installed by unqualified installers and the earthing effectiveness is not being tested.


Also his shop has nuisance tripping of the R.C.D. when several appliances are turned on. In particular washing machines cause tripping. Probably down to the 50 appliances each leaking a small current to earth via their internal mains filters. Get the cheapest quote. That''ll do. That's Norfolk for you.



Z.


Z.
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    mapj1:

     At the level of Dangerous Dave's Domestic Appliances Installed Daily  (*), a continuity check with a  wander lead from the new cooker or new light fitting to the earth pin on a nearby socket would be within the capability of anyone who can read a multimeter and do their own car electrics. It does not need a £1000 multi tester, at a push a torch bulb and battery would do, and would be an easy 2 sentences to add to the fitting instructions.

    We don't honestly need an ELFI value accurate to 3 significant figures,  - that was presumably designed to be right at some earlier point, we just need to know it is not open circuit now because the screw has fallen out.


    (*) Apologies if that is anyone's real company, like the Far Eastern Dangerous Toy and Lawnmower Import Company I used in another post,  any resemblance is unintended and accidental.




    The continuity test from cooker exposed conductive parts and the earth pin of a nearby 13 Amp socket confirms that the two items are connected together electrically, BUT are the two connected effectively to Earth? They may not be.


    A torch bulb and battery may confirm that a few milliAmps can pass through  the route but will not prove that the route is good enough to carry a large fault current sufficient to operate a protective device like a fuse or M.C.B. The circuit may only be hanging on by a strand or two of fine copper or a loose screw terminal.


    Z.

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  • 0

    mapj1:

     At the level of Dangerous Dave's Domestic Appliances Installed Daily  (*), a continuity check with a  wander lead from the new cooker or new light fitting to the earth pin on a nearby socket would be within the capability of anyone who can read a multimeter and do their own car electrics. It does not need a £1000 multi tester, at a push a torch bulb and battery would do, and would be an easy 2 sentences to add to the fitting instructions.

    We don't honestly need an ELFI value accurate to 3 significant figures,  - that was presumably designed to be right at some earlier point, we just need to know it is not open circuit now because the screw has fallen out.


    (*) Apologies if that is anyone's real company, like the Far Eastern Dangerous Toy and Lawnmower Import Company I used in another post,  any resemblance is unintended and accidental.




    The continuity test from cooker exposed conductive parts and the earth pin of a nearby 13 Amp socket confirms that the two items are connected together electrically, BUT are the two connected effectively to Earth? They may not be.


    A torch bulb and battery may confirm that a few milliAmps can pass through  the route but will not prove that the route is good enough to carry a large fault current sufficient to operate a protective device like a fuse or M.C.B. The circuit may only be hanging on by a strand or two of fine copper or a loose screw terminal.


    Z.

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