Earth rod

[mickys86]

Hi guys. I've been reading a few posts about earth rods. What's the preferred way to join them, and also when installing a few of them what is the preferred way to link them? I've read some posts that says when installing them next to each other you should spread them apart the same distance as you go down. But none to answer my above question. Cheers

 

[Engineer54]

There is only ONE way to couple rods together and that's using the manufacturers couplings!!

You never install earth rods next to each other, they must be a Min distance apart, based on the length/depth of the adjacent buried rod, but better to add a metre, as unless you measure by testing you won't know if you have overlapping areas of influence.

You connect multiple rod positions by appropriately sized earth conductors, preferably using manufacturers rod clamps, U bolt clamps, exothermic welding, braze welding, etc, etc!! Don't use the general pipe earth clamps, they are not suitable for buried exposed to elements earth rod connections....

 

[mickys86]

Thanks E54 I was wondering if the cpc had to be continuous between the rods. Its difficult to explain.....
Let's say from the earth block to one rod, Joined to that rod, then we decide to put another earth rod in. Would it be acceptable to link the the Rods together?
I must stress that I am asking hypothetically. I like to know these things

I have an earth rod to install. It seems the acceptable way to install it is to join 3-4 together? Am I correct

 

[Guest123]

Some info here.

 

[huntos33]

Am i missing something ? ive never seen more than one rod drove into the ground ?

 

[mickys86]

Am i missing something ? ive never seen more than one rod drove into the ground ?

Ditto. But after reading some older posts it seems there's some things to be learnt.....

Thanks Lenny

 

[Guest123]

Am i missing something ? ive never seen more than one rod drove into the ground ?

There is a lot more to a TT system than just one rod poked into someones garden. Even meeting the minimum rule of thumb of 200ohms requires a couple of well driven rods at times.

Comm/Ind require a lot more thought.

 

[trev]

Am i missing something ? ive never seen more than one rod drove into the ground ?

It's a very common misconception that one skinny little copper twig is all you need and that as long as you hit 200 ohm you're good to start loading the van up. As many of us have stated before with a little bit of thought and effort you can achieve stable, very low Ra.

 

[huntos33]

It's a very common misconception that one skinny little copper twig is all you need and that as long as you hit 200 ohm you're good to start loading the van up. As many of us have stated before with a little bit of thought and effort you can achieve stable, very low Ra.

I was at one yesterday 40ohms just assumed this to be ok, never thought about adding more to be honest my own house is tt on a 10mm with a skinny rod around 30 ohms earthy soil in the south west !!

So how low would you get it ? i mean there has to a limit when you stop banging in rods ?

 

[huntos33]

looking through my test sheets now !! been to one this year on a single rod at 0.50 ohms , guess it depends on soil and ground conditions ?

 

[trev]

If I were installing a TT I would do exactly as Glenn suggested. Get 3 X 5/8 (or whatever the metric equivalent is) couplable rods. I'd drive 2 of them, see what the result is, if I was happy with it, tools in the van and away I go.
If not happy I'd drive the 3rd one in and recheck.
In my experience the wholesaler will take the spare rod/s back. If they don't you have one for your next TT

 

[Engineer54]

Any values you achieved with a single 1.2m rod is unlikely to be a stable rod!! As ground can dry out or freeze during the seasons, rendering the rod virtually useless. In all honesty, you always need an absolute minimum of 2 X 5/8'' rods coupled together for depth. It's depth that will give you stability and lower Ra values.The thin 3/8'' twigs that are passed off as earth rods, should be taken out of circulation, they are basically useless, and can't be coupled together...

Those of you stating low Ra values with a single 1.2m rod, if correct, ...can be substantially improved by the addition of coupling an extension rod, (preferable for depth) or linking to another rod (2 X coupled 5/8'' rods) positioned outside of the area of influence of the existing rod location... Your aim, is for as low a Ra value as you can practibly achieve, ...NOT the numbty 200 ohms mentioned in BS7671!! lol!!

 

[huntos33]

All advice is good, trouble being paye for so long is when your chucked a twig and a clamp you just do it, also not being a domsetic godess does not help matters ,no company i have ever worked have so much as owned any kit for testing rods.

Now being the boss of myself i find lots of very helpfull advice thanks guys

 

[trev]

At least now you're getting an idea of how to do it properly mate

 

[mickys86]

All advice is good, trouble being paye for so long is when your chucked a twig and a clamp you just do it, also not being a domsetic godess does not help matters ,no company i have ever worked have so much as owned any kit for testing rods.

Now being the boss of myself i find lots of very helpfull advice thanks guys

So what advice do you give to someone on paye who has been given 1 earth rod to put in and only having a mft to test with. I tested Ze (my next question soon will be what's Ra) and the value I got was 179ohms. When I told my boss he said its below 200 so it's allowed......

When you join the rods do they clamp together or screw into each other? Because the rod that is in is just 1m copper rod. I need sound advice so I can learn something and also do the job right.