Multiple earth spikes ???

[FIAT LUX]

Here

 

[Andy™]

general rule on distance apart is twice rod length. id measure each rod (to make sure its getting some reading), then test as one to get Ze, adding as many as necessary. also allow for ground drying out

 

[matt.leung]

you could always use earth tape or plates...

 

[SPECIAL LOCATION]

Hello Fiat Lux...

NICEIC guidance suggests as follows:-

5.2 The use of additional earth electrodesWhere the resistance of a single electrode is unacceptably high, a number of such electrodes may be connected in parallel. Clause 10.2 of BS 7430: 1998 states that where a number of vertical rod or pipe earth electrodes are so connected, the combined resistance is then practically proportional to the reciprocal of the number employed, provided that each is situated outside the resistance area of any other. The same clause states that, in practice, it is often assumed that such rods or pipes are outside of each other

 

[Apache]

which in summary says...

not less than the depth of one spike..

but no major advantage going greater than 2x spike length!

Are you sure it does? To quote your quote:

it is often assumed that such rods or pipes are outside of each other

 

[Evans Electric]

Fiat, I don't envy you with that kind of ground . I put 5 rods in soil linked together and still had no reading. No idea why .

 

[Andy™]

Fiat, I don't envy you with that kind of ground . I put 5 rods in soil linked together and still had no reading. No idea why .

you need to turn test kit on...

 

[green-hornet]

Fiat, I don't envy you with that kind of ground . I put 5 rods in soil linked together and still had no reading. No idea why .

Your meter was turned off?

well thats one idea

Fiat you have a major problem as far as the ground is concerned, this would normally require some expert electrical engineering, going as far as some geophysics.

If its really rural there may be a posibility to establish a remote earthing station, often installed beyond a bedrock, however this would have to be investigated as a possibility.

Multiple rods if connected together may not give you the required resistance.

You may have to place some earth mats down, if there is enough land available. This gives a greater mass to earth than a rod, or multiple rods can do.

This is a network of tapes or plates to spread the surface area to earth, hopefully giving a better earth.

The other option is to core drill the rock and insert a rather long rod,not a financially viable option I would have thought.

 

[kme]

Are you sure it does? To quote your quote:The way I read that is if you drive 2 X 1 meter rods in they need to be 2 meters apart?

:|

Would concur with "electrivet" on that - distance of BOTH spikes into account methinks??????

 

[Evans Electric]

This raises the question , after wanging 1000 rods in and still getting carp reading what does one do? I spent a day on those rods , in the end I kept it TT but used the incoming cable sheath ( 14 ohms)

 

[kme]

If you put 1000 rods down in one day, then I know why you didn`t have a reading worth a damn.....

"You`ve got to send the buggers more than a couple of inches down!!!"

Or, you could`ve laid the rods end to end, theyd`ve reached to either a substation or a pylon. Good earth available at either...Guiness DrinkO)

KME

 

[green-hornet]

This raises the question , after wanging 1000 rods in and still getting carp reading what does one do? I spent a day on those rods , in the end I kept it TT but used the incoming cable sheath ( 14 ohms)

Connection of remote ground grid and adjacent grounding facilities

Use of deep driven ground rods and drilled ground wells in combination with a chemical treatment of soil or use of bentonite clays for backfilling.

Use of counterpoise wire mat. Copper clad steel wires of AWG No 6 size, arrange in 0.6mx0.6m grid pattern, installed 0.05-0.15m depth, then the main grounding grid 0.3m-0.5m.

A nearly low resistivity material can be used as extra grid. Example: clay deposit, part of large structure such as concrete mass of hydroelectric dam

Well you did askROTFWL

 

[Evans Electric]

Cor blimey guv'ner , I only arsked !!! :|

As with some of the others ,working in a large urban area ( West Mids) TT was a rarity but not anymore .

 

[SPECIAL LOCATION]

Are you sure it does? To quote your quote:The way I read that is if you drive 2 X 1 meter rods in they need to be 2 meters apart?

:|

erm....

NOPE!

"such rods or pipes are outside of each other

 

[Apache]

I do think from the quote in post 4 it's a bit ambiguous!

(not your fault SL - your source's )

I do wonder if we are counting the same bit of 'earth' around the rod twice if we have them a meter apart. I imagined a 1 meter radius cylinder around the rod to dissipate fault current to earth.

 

[a1]

"electrivet"

ROTFWL

 

[FIAT LUX]

Thanks to everyone for their very helpful replies (as always!)

 

[ericmark]

I wonder what you are using to measure with? In UK we often use the earth loop impedance tester but that is where the suppliers earth is 21 ohms or less. Where supplied by non UK suppliers then they may not follow the rules we have in UK. So you may need to use a bridge to measure resistance of rods and this also relies on the two test spikes.

Even in the UK I have seen where pole mounted transformers are used then earth has eroded away and the suppliers earth is well over the 21 ohms. However not to get 200 ohms is very rare.