British gas TT earthing and rcds

[netblindpaul]

Rods should be a minimum of 2x depth apart from memory from 7430, though I would need to check, that is what I was taught and have always worked to.

Can't look it up now go to go, wife has just been ill.

 

[ImpededLoop]

Just checked Guidance Note 8 which says the spacing should be at least equal to the length of the rods used.

Edit: Page 28 GN8

 

[davesparks]

Rods should be a minimum of 2x depth apart from memory from 7430, though I would need to check, that is what I was taught and have always worked to.

Can't look it up now go to go, wife has just been ill.

That's a new one on me, I shall try and get some more research into the subject done

 

[Engineer54]

Just checked Guidance Note 8 which says the spacing should be at least equal to the length of the rods used.

Edit: Page 28 GN8

All very much depends on the the resistivity of the soil the electrodes are being used in. With a good soil resistivity the spacing between the earth electrodes need to increase to avoid electrode zones of influence overlapping.

My general rule of thumb for small installations is 1.5 to 2 X the buried rod length when soil resistivity isn't known....

 

[Knobhead]

My use of 8' and 10' originates in an entry in Stubbs' electrical encyclopaedia, which although it is a bit out of date seems to concur with modern information I have read on the subject.

Stubbs may be old but it’s a mine of information that’s still relevant. Electrical theory doesn’t change.

 

[Engineer54]

Originally Posted by davesparks
My use of 8' and 10' originates in an entry in Stubbs' electrical encyclopaedia, which although it is a bit out of date seems to concur with modern information I have read on the subject.

Stubbs may be old but it’s a mine of information that’s still relevant. Electrical theory doesn’t change.

Up until recently (last couple of years) i'd never seen a 1.2m 5/8'' rod, and was told at the time they were extention rods only. I've still never seen these 3/8'' twigs/test spikes they call earth rods!!

The majority of the earth rods i've used over the years are generally 3/4'' X 2.4 or 3.2m extendables with the odd project using 5/8'' X 2.4 or 3.2m extendable.