Bringing down Ze?

[Ross1]

Hi,

Im getting a Ze reading of 580 ohms on a TT installation, the existing earth to rod is either a 2.5 or a 4mm and im not sure of the route.

My question is if I run a 10mm earth (approx 35m) how much will it bring down the Ze?

 

[IQ Electrical]

How long are these rods generally and what depth would be a good start mate?

The standard length for 9, 12.5 and 15mm copper/copper clad rods is between 1.2 and 1.5 Metres.

Get a couple of rods and a coupler, drive the first and take an Ra reading before going any further, you'll have a good idea of soil conductivity by then.

 

[ian.settle1]

How long are these rods generally and what depth would be a good start mate?

Have got to agree it does not matter what size your cable to to the electrode is,

If the electrode does not make a good contact with earth then you will get a Ze high reading

 

[Geordie Spark]

I needed to instal a temporary rod recently & used a 5 foot length of 15mm copper pipe bashed into the rear lawn.

I was surprised to get a reading of 74 Ohms - I was expecting something much higher.

Since then, I've got the installation converted to TN - S & removed the copper pipe.

 

[Engineer54]

I noticed some of the lads on this site suggesting an item that fits in a drill that is used for impacting the rod into the ground
I have always used brute force with the trusted lump hammer,so cant comment more on them.but maybe someone else can

That's right, there is an attachment that fits SDS gizmo's, and can be very useful. The trouble with club hammers and the like they can spring the rod during the heavy hammering. You end up with quite a large entry hole... lol!!! ...Personally i would be using 3 rods whenever possible. The project i'm working on now are using 3.1m 3/4'' rods, dropped in bored holes filled with an enhanced (carbon particles) bentonite slurry. These being part of a sizable site earth field in banks of 15 to 20 rods positions.

One more thing to note when using extension couplers to extend a direct driven rod depth. Is that because these couplers have a little wider diameter than the rod itself, it can take upto a year or so to achieve the full potential of your deep driven rod. The ground soil needs to fill and compact to make that good contact with the rod. That's not to say that the first rod (that is in direct contact) isn't going to going to give you a far, far better Ra value than a single rod straight off!! ...lol!!.

 

[Ross1]

Thanks for the advice yesterday fella`s, i knocked my first ever earth rod in today. I bought 2 x 5/8 1200mm long rods and a coupler. I hammered the first rod in and took a reading and only got 660ohms........getting worried i fitted the second one with coupler and hammered that baby home and bingo, I got 167 ohms which was good enough for me

Cheers guys

 

[yellowvanman]

If you're doing lots then try this!

Rapid Electronics - SDS-Max Earth driving rods

 

[daiplayer]

Wouldnt installing a secong rod be better ? ...ie creating a parralel path ?

 

[Ross1]

If you're doing lots then try this!

Rapid Electronics - SDS-Max Earth driving rods

thats a niffty tool there, might need to invest in one as alot of my work is TT installs. Cheers mate

 

[daiplayer]

Wouldnt installing a secong rod be better ? ...ie creating a parralel path ?

Sorry ...didn read the full thread :-/

 

[Engineer54]

Wouldnt installing a secong rod be better ? ...ie creating a parralel path ?

Better than installing a single rod yes, but no-where near as effective as going ''Deeper''

 

[daiplayer]

Better than installing a single rod yes, but no-where near as effective as going ''Deeper''

Really ? .....wouldnt have thought tha.... ( im a newbie to most of this btw so dont go thinking ive got my own thought on this ) lol

 

[Engineer54]

Thanks for the advice yesterday fella`s, i knocked my first ever earth rod in today. Cheers guys

thats a niffty tool there, might need to invest in one as alot of my work is TT installs. Cheers mate

So...Which is it then?? lol!!