Jb wrote:

This is without doubt an old voltage trip and needs scrapping.

Thought as much...

Many properties of this age were earthed to a rod using steel wire and over
the years lost the connection to rust so it may well have disappeared by
now.

I could not even find evidence of a wire inside - the only obvious one
running downward from the install was the one to the gas main. If there
was a rod is it also possible it got burried when the previous owners
laid the concrete drive which continues up the side of the house beside
where the meter cupboard is located.

Asking how many earth rods is a bit like asking how long is a piece of
string. You need a meter to check (not a multimeter) the final earth
resistance. Don't make the common mistake of banging in rods close to each
other thinking more is better; getting them too close actually increases the
resistance. In clay you probably only need one but you buy a 'proper' earth
rod they will screw together to achieve a greater depth should you need to.

My plan was to measure the fault loop impeadance of what is there first
to see what the starting point is, and then add at least one proper
earth rod and carry on unitl I get a decent low enough value. Finally
add the cross bonding to the water main.

--
Cheers,

John.

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