Earth spike

[faceman]

Hi

Im newly qualified and i am working on a domestic property that requires an earth spike, which i have never done before. From what i can tell the property was being eathed through the incoming water before.
I need to know any specifications required when using an earth spike. Obviously an RCD is required but what size cable? is there a certain distance required from the property? if so i guess this will affect the cable size..?. Also what is the depth required..is it 3m...or does it depend on the reading you get? Also does it have to be contained in a manhole type box with access panel?

Its a 100amp main fuse with a 6way Rcd protected fuse board.

Any help would be great. thanks.

Steve

 

[Des 56]

The cable size for aTT earth can be calculated and in the majority of cases cable as small as 2.5mm is more than sufficient,this is not permitted however because of the possibility of mechanical damage

In practise I generally run 10mm and mechanically protect it where it is external,others may use 6mm and some prefer 16mm which can then be unprotected


The earth box can be what you/they are prepared to pay

It can be a small plastic conduit size terminal box with a cover and label or the full monty inspection chamber

Using these depends very much on the location and can it be fitted, I'm thinking, "terraced house" no way
Detatched buiding with soft ground the chamber may be ideal

A standard rod is about 4 ft (Never ever measured the lenghth though )
If the reading is poor,then rods connected to rods can be used,so the depth may be as deep as the lump hammer you are using will permit
Distance from the building is not absolute.just remember that the foundation concrete may be wider than the building and too near may cause difficulty