TT Earthing

I intend wiring up a remote garage so it will have a TT earth.What is the best way of protecting the exposed part of the earth rod and the cable clamp from the elements outside?Could I drill a hole through the garage base and hammer the rod into the foundations so the top is inside?I don't have and specialised test equipment, how do I know for sure I have a good earth except by deliberately causing an earth fault to check the RCD? Mark Atherton
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RCD?
Borrow an earth loop impedence tester. Connect earth to the rod and live to your supply (before the RCD, or with the RCD shorted out). Press Test. You need a much better earth than that required to simply trip the RCD. The tester will attempt to draw up to 20A and measure the voltage drop.
Technically, you can get away with higher impedences without breaking the rules, but 200 ohms is a recommended maximum to allow some margin. You should be aiming for much less that this, unless you have some sort of problems with soil or rocks.
Christian.
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"Mark Atherton" wrote in message
og40>. With a 30 mA RCD the earth electrode resistance must be less than 1600 ohms (500 ohms with a 100 mA RCD) but, as Christian says, the OSG recommends a figure of under 200 ohms to give a large margin of safety in case of drying out or freezing of the soil.
HTH
--
Andy



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Something like:
http://www.screwfix.com/app/sfd/cat/pro.jsp?id 092&ts558
?
Darren
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"dmc" wrote in message

That's the sort of thing. The Furse one is round at the bottom, and probably a bit smaller than that though. Thanks for finding the picture.
--
Andy



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