Length of earth rod

[Pandora]

I'm proposing to run a 230V electricity supply to my garage (30m from house) using underground SWA cable.

I need a ground rod to supply the garage with a safe earth. The salesman at Furse told me that the standard domestic rod is 3/8" diameter x 1.2m length.

A few electrical wholesalers I've phoned, however, stock 3/8" x 4ft as "standard". Is 4ft likely to be OK? The garage is above quite a high water table.

Can I drive the rod straight into the soil outside the garage and protect the top with a cover?

I'll measure the rod resistance on a dry day soon after installation.

[Grunff]

4 foot = 1.2192m - so what's the problem?

[Christian McArdle]

4ft IS 1.2m.

There is no mandated length. You must test the rod with specialised test equipment (NOT a multimeter!) to determine the impedence and ensure that it is low enough (and likely to remain so). The length (or number) required will depend very much on your soil type and expected seasonal conditions.

Christian.

[Nick Brooks]

4 feet = 1.2192 meter

Should be OK

possibly not if your soil is really hard/stony in which case you'll have to dig

[Pandora]

Doh!!! How stupid do I feel?

Hope my family and friends never come across this thread.

[troubleinstore]

Nah, don't worry about it. Even the so called professionals make mistakes and boy, have I seen some.

-- troubleinstore