Installation regs on multiple earth rods.

burnzybubbles · Jul 30, 2018

Hi everyone, just a quick question, Earth rods aren’t my strongest subject and I have no access to my 7671 at the mo, what’s the regs or guidance for installing multiple Earth rods?

Issue I’ve had was services in the way, can the Earth rods be put into a different pattern than a square or a straight line? Like an L shape for instance? I have no clear route for the standard ways and it seems the only possible solution.

Thanks.

telectrix · Jul 30, 2018

think it's the spacing of the rods is more critical than the layout. aslong as you get decent readings, who gives a ----?

burnzybubbles · Jul 30, 2018

Better to ask than just plow ahead and do

Like I said I’ve never really had to deal with installing Earth rods so I’m learning as I go.

Common sense does point towards it not being an issue but I thought I’d just ask

Thanks though.

Wilko · Jul 30, 2018

Hi - no regs that I know of, just design practice as Tel has said. If you're using multiple rods the advice from GN8 is to space them at least as far apart as they are deep. I generally use 2 x 1.4m rods joined and repeat until the right Ra is obtained. I put them about 3m apart. Hope that helps

Gavin John Hyde · Jul 30, 2018

I have always where size of the ground permits, spaced them the same as the length apart, so if the first rod is 2.4m the next should be 2.4m away. Although in fairness its rare to need another if i have got 2.4m in. i put a rod in yesterday for a rolec charger, got a decent reading of 88 ohms on a single 4 footer.
Got myself a nice new tool for driving them in now too, cost me £30 on ebay and fits in the sds drill and over the rod and then on hammer action only drives them in nice and easy, no more swinging hammers about! for some reason they are all sold as ground rod driver as they are imported from the good old us of a.

burnzybubbles · Jul 30, 2018

That’s brilliant thanks, yea was going to use 2 rods but 2.4 apart, so I’ll just stretch it to more like 3m instead

burnzybubbles · Jul 30, 2018

Gavin John Hyde said:
I have always where size of the ground permits, spaced them the same as the length apart, so if the first rod is 2.4m the next should be 2.4m away. Although in fairness its rare to need another if i have got 2.4m in. i put a rod in yesterday for a rolec charger, got a decent reading of 88 ohms on a single 4 footer.
Got myself a nice new tool for driving them in now too, cost me £30 on ebay and fits in the sds drill and over the rod and then on hammer action only drives them in nice and easy, no more swinging hammers about! for some reason they are all sold as ground rod driver as they are imported from the good old us of a.

I’ve seen the tool on eBay already thanks, I was going to take a grinder to an sds max bit and make my own

the rods came with a large Allen head bolt which I presume to be for the installation so I’ll just make something that fits into that

The ground is really bad where they are being installed so they’ve asked for 4 to be installed and we’ll see how we get on.

Taylortwocities · Jul 30, 2018

Earth rods can interfere with each other if they aren't far enough apart.
3metres separation should be ok. but its a black art: here's a sample from a document on the subject

[ElectriciansForums.net] Installation regs on multiple earth rods.

netblindpaul · Jul 30, 2018

BS 7671 defers to BS 7430 on the detailed information and specifics of earthing, and there is a bit to it, but, to avoid interference rods should really be twice the driven depth apart.

burnzybubbles · Jul 30, 2018

Thanks guys so far, more than enough to chew on

Strima · Jul 30, 2018

Quite a good explanation of sphere of influence here: Grounding Electrode Sphere of Influence - E&S Grounding - http://www.esgroundingsolutions.com/grounding-electrode-sphere-of-influence/

Installation regs on multiple earth rods.

burnzybubbles

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telectrix

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burnzybubbles

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Wilko

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Gavin John Hyde

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burnzybubbles

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burnzybubbles

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Taylortwocities

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netblindpaul

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burnzybubbles

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Strima

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