Earth Spike Test Kit

[uksparks]

Hi,

I ordered a Fluke ES165X Earth Spike Test Kit yesterday, arrived this morning, has a go with it in the garden, popped a single 5/8 rod in and got 57 Ohms, im going to stack another two on top of it and see what I get after the weekend when the shop opens again as have no more rods!

The kit is quite good.

I thought I would get one as have a job in a week or so where I am going to be putting a few rods in to get a good reading and would like to put them in before I run the SWA down to it, so will be able to get my earth ready!

I am going to aim for sub 1 Ohm! Ill keep you posted on what happens with that. I won't give in until I get under an Ohm.

 

[Marvo]

I'd be interested to know how many rods you need to get a sub-ohm Ra. The last one I did we needed 64 x 2.3m rods and it took some effort, final Ra was 0.3 or 0.4 ohms I think.

 

[PEG]

Fair play to you,i love it when a dude gets enthusiastic about a task,and it is this which drives us to better ourselves,and keep standards high.

I don't know what ground you possess,but sometimes sub 1 Ohm is just not attainable,which should never deter us from trying.

I look forward to your results,and if you are as sad as i,you may decide to take readings at differing stages of sinking your mini fracking drill...

The core of our planet is especially conductive,so tally-ho :yes:

 

[Marvo]

I'm not sure what length rod he used but 64 ohms from a single rod is the kinda figures I can only dream about getting. If it was a short rod then a sub-ohm result might not be out of the question if he couples another 2 or 3 rods onto it and gets some depth then repeats the procedure further up the garden.

 

[rustynails]

64 ohms from a single rod is the kinda figures I can only dream about getting

Me too. Most of the figures I get round here are around the 100 mark. I've got this kit and it is very occasionally useful.

 

[uksparks]

I have done very little with earth rods, so its a good opportunity for me to have a good crack at getting a good reading.

Ill put a 1m rod in first and see what I get make a note, then put another meter on top and make note again, then put a third on top of that, see what I get, then ill hook another rod up about 10 meters or so away, again start with 1m, then 2m, then 3m and have that connected to the first rod, hopefully ill be able to get a good reading from this, if not, ill just put more rods in.

Im confident ill be able to achieve the figure I want as its very close to flood plain and low land so should have quite wet ground when a rod or so down into the ground.

Do you think I would be better trying to go deeper at one location say 4m - 6m or would you say put another rod in 10m or so away? I don't really know which is better? I do know that a deeper rod is going to be more stable but is there a limit to how far you can go without making any additional benefit to the reading?

 

[Richard Burns]

It is really going to depend on the type of soil you have, the method of driving you are using and the space you have available.
If you are going 3.6m deep then the next rod can be only 4m away (though 10m would be certain).
Market Harborough seems to be generally on clay sand and gravel with mud to the north, so this should be a reasonably low resistance substrate especially as there are aquifers through the ground, but your local conditions may vary from the average.
This would mean that a 3.6m rod should be OK, but maybe not sub 20Ω.
If you are driving by hand then you may find it too much to go beyond 2.4m.
If you can get a rod 10m away then you have plenty of space for a network of rods, but it would be best to ensure they do not interfere with other activities in the area.
Measuring correctly and repeating your measurements may give you better results so ensure you have followed the correct procedures.

 

[uksparks]

Thanks for the lengthy response, much appreciated.

althpugh my nest of rods will be between 70m and 80m from the house, it's probably only 20m from a load of nbrand new houses, your reference to not interfering with other areas, how best do I avoid the issue or know what I'mblooking for as to put them in the best position?

thanks

 

[Sintra]

Handy little pdf on the subject.

 

[Marvo]

Ill put a 1m rod in first and see what I get make a note, then put another meter on top and make note again, then put a third on top of that, see what I get, then ill hook another rod up about 10 meters or so away, again start with 1m, then 2m, then 3m and have that connected to the first rod, hopefully ill be able to get a good reading from this, if not, ill just put more rods in.

Rather than using 1 meter rods use 2.3 meter. You can knock them in half way, take a reading then knock the rest in and take another reading. It will save you on couplings and work out cheaper.

Do you think I would be better trying to go deeper at one location say 4m - 6m or would you say put another rod in 10m or so away? I don't really know which is better? I do know that a deeper rod is going to be more stable but is there a limit to how far you can go without making any additional benefit to the reading?

Go as deep as you can in a single location. We usually manage about 10-12 meters per rod before it becomes too difficult to carry on. Obviously the depth you can go is limited by the geology in your particular area.

I'll give you some advice, either use one of these with an SDS-Max earth spike driver attachment

Or you can use one of these and we don't bother with an attachment, we just use ours straight onto the rod. If the end of the rod becomes mushroomed we cut off the last 10mm with a battery grinder so a coupling can then be fitted. If you use the larger jackhammer just be careful if you need to use it with stepladders, they're a bit tricky with the balance.

 

[Richard Burns]

Thanks for the lengthy response, much appreciated.

althpugh my nest of rods will be between 70m and 80m from the house, it's probably only 20m from a load of nbrand new houses, your reference to not interfering with other areas, how best do I avoid the issue or know what I'mblooking for as to put them in the best position?

thanks

Have look at the spheres of influence part in Sintra's pdf.
Try and determine the route of the supply cable (easy if it is overhead) and avoid locations within 4m of the cable route (or the earthing points if overhead). However it is often likely in built up areas that you are overlapping spheres with the DNOs PME supply, which is not advised.
You also need to be sure you are not meeting your own earth rod spheres of influence where using multiple rods.
And ensure that your earth rods are unlikely to be disturbed by future works, I am sure at one customers house they built the extension over the earth rod!

 

[telectrix]

and if you have an underground supply cable, try not to spike your rod through it. :mad2:

 

[uksparks]

and if you have an underground supply cable, try not to spike your rod through it. :mad2:

Would I correct in assuming supply cables generally go into the road and not down the back garden?

 

[Richard Burns]

If the CU is at the front of the house on the road then yes, the DNO will take the shortest route into the house (in most cases, old properties and extensions excepted).

 

[uksparks]

Have look at the spheres of influence part in Sintra's pdf.
Try and determine the route of the supply cable (easy if it is overhead) and avoid locations within 4m of the cable route (or the earthing points if overhead). However it is often likely in built up areas that you are overlapping spheres with the DNOs PME supply, which is not advised.
You also need to be sure you are not meeting your own earth rod spheres of influence where using multiple rods.
And ensure that your earth rods are unlikely to be disturbed by future works, I am sure at one customers house they built the extension over the earth rod!

Move been reading up on the spheres this afternoon, makes sense!

i would think a 10m space between rods is going to avoid any overlaps.

As with what telectrix just said, the supply cable I can only presume should be going back into the road and not down the back garden? I can rent a CAT scanner for £20 locally so might just have a go with that to be on the safe side.

ill take a screen shot of Google Earth so you can see where it's going.