"Correct" way to connect an earth rod at a remote domestic location?

Question

I have a 230V supply to a small CU in an IP65 box in the garden. This box has a pump controller (for a well) and an external socket (both protected by RCBOs) plus an MCB-protected supply (via SWA) to a further point at the gate. At the gate the SWA enters an IP65 adaptable box which will have a gate controller and PIR-operated lights connected to it. The garden CU and the gate each have an earth rod to provide local TT earthing. I'm using 16mm2 wire and have these

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at the top of the earth rods

My questions are: what's the "correct" way to physically connect the earth rods? Should the wire from rod to box be protected in conduit? What's the accepted way to take it into the CU and adaptable box while maintaining the IP65 protection?

John Rumm · Accepted Answer

It does not need to be protected, but the CSA required will vary depending on if it is. There is a table here:

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(16mm^2 is going to be more than adequate for any style of installation)

The physical connection is usually a clamp of the appropriate size for the rod diameter. E.g:

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or

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A standard compression gland will do the trick:

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nothanks · Answer

Thanks, so are there really no protection requirements? It seems odd to just run a wire over soil so I've tended to put it in "unofficial" plastic conduit.

earth wire, hence the question. Silicone works wonders but I wondered whether there was anything made for the job because I've looked without success.

nothanks · Answer

Belay that. I just tried a different search and there are plenty available for smaller sizes - sigh! I seem to have an intermittent fault with my google fu ;-)

John Rumm · Answer

It's quite common to see a green/yellow single running out to an earth rod. The size dictated by the conditions usually (the earth rod impedance is not usually low enough to make the current carrying capacity of the wire relevant).

So no harm having it in a conduit etc (and in some cases more maintainable) but it would be ok without in many cases.

I picked that particular gland because it covered wire CSA from 13 to

18mm^2 (ironically I was going to link to the parent page with all the sizes on).

(BTW, if you a gland from TLC, you need to order the backnut separately... DAMHIK)

"Correct" way to connect an earth rod at a remote domestic location?

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