Earth rod distance to gas service

[Engineer54]

Bang on....what I've been trying to get E54 to see for ages......For that reason IMO there is little point in going to excessive lengths to achieve very low Ra's,which cant ever be relied upon to be stable enough for operation of all the overcurrent devices in an installation.

The point is, that i've always stated that a TT system for a domestic installation should always avoided and be a last choice not a first choice!!! If your stuck with a TT system, then that's another matter altogether. Then you do the job properly and wherever possible use deep driven rods of a decent diameter!! Depending on the soil type it is more than feasible to get an Ra far lower than 10 ohms and the deeper you go, ...the more stable the system will become. The common use of these thin short earth rods, ....and then only using ''one'' of them, is the main reason why it is so hard to get anywhere near a decent Ra value, an that's the real truth of the matter...

These lattice mats that have been mentioned above, are Not going to be anywhere near stable if buried at one metre or less, in fact there primary use is for rocky locations or where you can't drill or drive rods to any depth....

 

[Cider]

Im going to install a screw joined one (2 of) when I get the chance as the one I did went in a bit easy for my liking even though the Ra droped considerably from the old one

 

[Engineer54]

The deeper the better Cider, and if your only using 1.2M rods, then consider one more making 3.6m. ...Remember, that first metre of depth will be giving you nothing, during winters freezing weather conditions!!!!

 

[Cider]

Will do thanks

 

[04gallsopp]

iee say 100 ohms but nic eic are happy with 200

 

[telectrix]

iee say 100 ohms but nic eic are happy with 200

other way round, i think

 

[TinyT]

I got a rod down to 1ohm before, at the side of a road in the centre of london. About 3 lots of 8 5/8 rods. Used a kango though.

True story.

 

[Dunc]

I got a rod down to 1ohm before, at the side of a road in the centre of london. About 3 lots of 8 5/8 rods. Used a kango though.

True story.

Miles of gas and water pipes make great fault paths when you've hit a few of them don't they! :rofl:

 

[TinyT]

Miles of gas and water pipes make great fault paths when you've hit a few of them don't they! :rofl:

When it feels like you have hit a void piece of ground, you know your in the underground system.

 

[Engineer54]

I got a rod down to 1ohm before, at the side of a road in the centre of london. About 3 lots of 8 5/8 rods. Used a kango though
True story.

Glad to see, that there are still those that are prepared to do a decent job of creating a good TT system. Sounds like you missed the predominant London clay, you wouldn't have had to use anywhere near as many rods!! ...lol!!

I wouldn't be a bit surprised that if you went back and retested that TT system, one to three years later, you would find your Ra will be well within the ''sub'' 1 ohm value!!! As most deep driven rod values, improve over the first few years....

A kango or similar purpose made mechanical hammer, is the only sensible way to deep drive rods past 3 metres...