Todays Earth Rod Efforts

uksparks · May 15, 2015

Hi,

As I mentioned last night, I was going to be putting the earth rods in for this summer house this morning.

I put 8 rods in, this was one stack of two, and two stacks of three rods.

The readings from the two that were 3 rods deep were around 10 Ohms per location, and the two rod stack was approx 17 Ohms.

I tested the first rod at approx 10 Ohms, then connected the second rod to the first which was 17 Ohms which them reduced the total down to approx 6 Ohms, then connected the third rod which was 3 deep and that bought it down to 3.2 Ohms.

So the Ra that I achieved today was a respectable 3.2 Ohms

All rods were connected together with 16mm earth.

I am going to go back next week and bang in another couple of piles of two rods so another four in total because I want to get that sub 1 Ohm reading.

Anyway, what do you think, 3.2 is not bad is it!!

Reading from first rod: 10.6 Ohms (3x 4ft 5/8" Rods)

[ElectriciansForums.net] Todays Earth Rod Efforts

Reading from second rod: 17.2 Ohms (2x 4ft 5/8" Rods)

Reading from third rod: 9.6 Ohms (3x 4ft 5/8" Rods)

Reading from first and second rod combined: 6.3 Ohms

Reading from all three rods connected together: 3.2 Ohms

NDG Elecs · May 15, 2015

uksparks said:
Hi,

As I mentioned last night, I was going to be putting the earth rods in for this summer house this morning.

I put 8 rods in, this was one stack of two, and two stacks of three rods.

The readings from the two that were 3 rods deep were around 10 Ohms per location, and the two rod stack was approx 17 Ohms.

I tested the first rod at approx 10 Ohms, then connected the second rod to the first which was 17 Ohms which them reduced the total down to approx 6 Ohms, then connected the third rod which was 3 deep and that bought it down to 3.2 Ohms.

So the Ra that I achieved today was a respectable 3.2 Ohms

All rods were connected together with 16mm earth.

I am going to go back next week and bang in another couple of piles of two rods so another four in total because I want to get that sub 1 Ohm reading.

Anyway, what do you think, 3.2 is not bad is it!!

Reading from first rod: 10.6 Ohms (3x 4ft 5/8" Rods)
View attachment 29132

Reading from second rod: 17.2 Ohms (2x 4ft 5/8" Rods)
View attachment 29134

Reading from third rod: 9.6 Ohms (3x 4ft 5/8" Rods)
View attachment 29133

Reading from first and second rod combined: 6.3 Ohms
View attachment 29135

Reading from all three rods connected together: 3.2 Ohms
View attachment 29131

Good work. Bet you only get down to 1.5 ohms with the next rods driven in mate....sods law I think we call it! You could always put any RFCs on a 20A and tell them they can't use their electric shower and hob!! Tell them disconnection times are very very important!! Look forward to the update mate.

Neil

mechelec · May 15, 2015

3.2ohms is not bad it will be better when you get it finished ; )

Richard Burns · May 15, 2015

No a load of rubbish, pull them all out and start again!!:mad2::53:

I would say 3.2Ω is a pretty good reading, 71A fault current enough to trip a 10A MCB.
Pretty close to the resistors in parallel results actually which is interesting to know.
Thanks for putting in the effort to give us some feedback.

uksparks · May 15, 2015

I think I'll put two more locations in and end it there, I bet each will knock an ohm off the figure.

it about killed me off beating them in with a lump hammer!

By the time the group has settled the reading will have got better as its really only the bottom rods that are in are touching the earth as the others are flapping round due to the couplers.

Richard Burns · May 15, 2015

Manually driven gives you some definite points, I am just not sure if they are for stupendous effort or stubborness!

NDG Elecs · May 15, 2015

Richard Burns said:
Manually driven gives you some definite points

I think the points are called callouses aren't they!

uksparks · May 15, 2015

The first one was easy, the second was a little touch, but the third rod was the killer, the deeper you go, it just gets sodding hard work.

I need to achieve a higher fault current really as 71A is pants, just looking at the time current tables in the BYB and max zs etc.

Andy78 · May 15, 2015

I applaud your efforts with this one I really do. Looks like you will end up with something close to very good.

I have to say though, driving coupled rods with a lump hammer..... don't you like yourself very much ?

Marvo · May 15, 2015

uksparks said:
I think I'll put two more locations in and end it there, I bet each will knock an ohm off the figure.

it about killed me off beating them in with a lump hammer!....

You must be mad, get an attachment for a jackhammer. Also if you want a better Ra go 1 rod deeper on all your existing locations rather than making new locations.

By the time the group has settled the reading will have got better as its really only the bottom rods that are in are touching the earth as the others are flapping round due to the couplers.[/QUOTE]

uksparks · May 15, 2015

Im not going to get a 0.2s disconnection with 71A, so need to improve that some what!

How many amps am i going to need to get 0.2s ? I know its RCD protected but thats not the point!

uksparks · May 15, 2015

Marvo said:
You must be mad, get an attachment for a jackhammer. Also if you want a better Ra go 1 rod deeper on all your existing locations rather than making new locations.

By the time the group has settled the reading will have got better as its really only the bottom rods that are in are touching the earth as the others are flapping round due to the couplers.

[/QUOTE]

I could try putting another on the top of them, I could do with someone holding the rod so i can hold the hammer with two hands.

Corbs · May 15, 2015

I could try putting another on the top of them, I could do with someone holding the rod so i can hold the hammer with two hands.[/QUOTE]

or one of these

much easier

[video=youtube;vvCZvNj8H30]https://www.youtube.com/watch?v=vvCZvNj8H30[/video]