Earth rod virgin needs help

30 Oct 2012
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United Kingdom
Hello All, I drove in my very 1st 4ft 3/8" earth spike today...feeling VERY macho wielding the lump hammer, but....using my dvm was only getting 3.5MegOhm , which, after watering the spike hole, improved to 1.5MegOhm . By comparison, the earth to neutral reading I get using the earth bonding on the incoming water main, gives me approx 40 Ohms (I know this isn't a Ze, but rather a resistance reading ,but does give some idea of the quality or lack of, my earth spike conductivity. Questions are:
a) When I connect together the bondings from the gas, water AND earth spike, the earth-to-neutral is going to be ..well, not bad, but JUST on it's own , the earth spike reading is lamentable. Is this a bodge and should I strive for a lower (much lower) earth to neutral reading ?
b) What to do to improve (lower) the earth spike-to-neutral resistance?
I've just been down to Screwfix and ordered up 2x 4ft 5/8" rods and associated hardware to join them together, but that'll be for another day. In the meantime...if you're still reading this...well, thanks! Any advice or observations/comments from you experienced earth rod installers will be very gratefully received.
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Earth rods need to be tested with the proper equipment. It was not in the megohms range, that is impossible.

If this is for an electrical installation, the impedance of the rod needs to be suitable on it's own, not connected to anything else. Values of less than 200 ohms are normally required, and generally under 100 ohms is far better. It's not measured between the rod and neutral either.

If it's too high then options include a longer rod, more rods, or some other arrangement such as a metal grid, mesh or tape.

A lump hammer may work eventually. An SDS drill is a more realistic option.

The top of the rod(s) must be protected, and the top of it installed below ground level (which is why a cover is required).
Hi, thanks for replying! Re the sds drill to drive in a spike... do you mean just using chisel action setting alone?
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