Earth Rod Resistance is high

[weston]

Hello All,

I hope somebody can give me some guidance.
I have an installation that is a TT system, the area is very sandy, down the hill from the distribution board is a lake, approx 70 Meters away. The rise is about 10 metres from the lake to the level of the DB.
Next to the DB enclosure I have installed an earth rod 5/8 extendable, this is 3M deep in the ground, reading 612 ohm.
I have installed 9 x 1.2M (11M approx) 5/8 rods straight down approx 5M from DB enclosure, reading 658 ohm.
I have installed 3 lots of 3 x 1.2M (3.6M) 5/8 rods stright down at a distance of 3M apart in a triangle arrangement down at the lake level, reading 512 ohm.
I can't seem to get the reading down low enough.

Any ideas before I install enough rods to raise the copper and steel content of the area.

 

[truckster]

Blimey are you on top of a sand dune?

I would hazard a guess that you need to go further down with your extendable rods until you hit better ground.

 

[malcolmsanford]

Bentonıte Powder can often help you, or the old fashioned way salt or coal.

I have to admit I had to once make a mesh in really chalky ground, but that is another job altogehter

 

[weston]

I thought 11M straight down would have been enough, but no.
Being down at the lake level I thought would have done the trick, but no.
Arrrh

 

[telectrix]

same here, near northwich. sand. afraid i don't have an answer, unless you can get DNO to provide PME.

 

[weston]

Sorry meant to say its a Caravan site, so its got to be TT....Arrrh

 

[weston]

Scottish Power have put a transformer in to supply the site, they have installed a HV and a LV earth in the ground 300M away from my DB, I don't know how they arranged there earth rods, mats or whatever they used, but I was told they had a good earth.

They did have a big hole dug though.

So it can't be impossible, can it?

 

[Marvo]

Next to the DB enclosure I have installed an earth rod 5/8 extendable, this is 3M deep in the ground, reading 612 ohm.

If you got 612 ohms with a 3 meter rod then I would whack another 3 or 4 x 2.3 meter rods on top of it and retest. I regularly need to go down at least 12-15 meters in our area which is also sand to get a decent earth reading.

 

[grimysparks80]

Have you tried tying a donkey to it?

 

[Amp David]

But a truck load of rods and an adapter for the sds and keep on drivin them in. Eventually you'll get a good reading

 

[Des 56]

Another variable is your test meter accuracy

 

[grimysparks80]

May be cheaper to run a 10mm to the next house

 

[telectrix]

a bonus could be a cheap tunnel to australia.

 

[grimysparks80]

How about moving the caravan.

 

[weston]

a bonus could be a cheap tunnel to australia.

I did think I would start getting lava up at some point....