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Old 4th Jul 2011, 8:11 am   #21
neon indicator
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Default Re: Is the mains 'earth' good enough?

All agrees. Pipe Earth bonds is purely for safety of anyone touching fittings. I think what ppppenguin says is true, try it. Just ensure the that if you are using mains earth it's via the 3 core mains flex and leakage is within limits.
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Old 4th Jul 2011, 10:22 am   #22
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Default Re: Is the mains 'earth' good enough?

Providing that the earth continuity on your property's internal electrical wiring is ok then it should be ok to use 3 core mains cable and only connect the earth wire of the cable into the earth pin of the plug, just make sure your plug does not have one of those plastic earth pins that are found on plugs for double insulated appliances.

You can test earth continuity by using a multimeter and measuring the continuity between the earth of the socket and a radiator water pipe that should ideally be connected to the ground of the mains, you should hear the continuity beep on the multimeter and the resistance should read 0 ohms.
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Old 4th Jul 2011, 11:31 am   #23
Red to black
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Default Re: Is the mains 'earth' good enough?

Hi,

Quote:
but any incoming service (water / gas /oil etc) should be bonded directly to the main earthing terminal, as close as reasonably possible to where it enters the building
What I think Rob was getting at (and he can correct me if Iam wrong), was if your pipe work is already bonded back to the Main Earth Terminal or 'MET' either in your consumer or otherwise (as it is supposed to be!), then your water/gas pipe will be already connected to your 'mains earth', so there is little/no advantage trying to connect your radio etc. to the water/gas pipe as opposed to the earth (CPC) in the plug, UNLESS as some posters have said, this 'earth' (FE see later) is isolated via an X2 capacitor or otherwise, if it isn't isolated you may introduce earth loops or other problems.

As others have stated, the earth in the mains flex/plug/socket etc. is a Protective Earth or PE, it is there to protect You from a lethal electric shock in the event of a fault.

If you add an earth rod solely to help the radio work better/better reception etc. then this will be a Functional Earth or FE, this is sometimes called a 'clean earth', and should be kept totally seperate from the PE, as this has nothing to do with protecting you from electric shock, it is there to enable the device to function as intended.
They are two completely different things

In the current Regs. a PE should be sleeved in the familiar Green/Yellow stripe, and the FE should be coloured Cream, some of you will have seen this on an RCBO 'earth lead'.
Also the rules are very strict on PE's (and rightly so!), where as there are next to none for FE (except follow the manufacturers instructions)

Some of the confusion arises, because manufacturers have sometimes 'combined' the functions of Both the PE and FE, into just a single conductor, ie. the CPC (Circuit Protective Conductor) in the mains flex, for both cost saving and convenience to the user.
Also the fact almost nobody uses 'Cream cable', and everybody just uses the 'common garden' Green/Yellow for FE aswell!

It also doesn't help that the wiring regs have changed many times over the years, and obviously on this forum we are using long since 'obsolete' equipment (and I mean this in the nicest possible way).

Needless to say that the Protective part takes priority over the Functional part EVERY TIME.

Cheers,
Baz
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Old 4th Jul 2011, 11:57 am   #24
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Default Re: Is the mains 'earth' good enough?

Thankyou Baz, that's a very good summary without getting too technical, which is what I was trying to avoid.
Rob.
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Old 4th Jul 2011, 3:05 pm   #25
neon indicator
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Default Re: Is the mains 'earth' good enough?

Brilliant Red to black / Baz!
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