You are quite right in saying that the RCD is strapped out.
The reason this came to my attention was an electrician working about half a mile away from this site was changing an RCD in a domestic property and noticed that there was 113V earth to neutral and 353V earth to phase.
After several hours of checking and testing other properties, supply cables and overhead line connections we got to the end of the line. I removed his yellow phase distribution fuse from the cut-out and the problem disappeared. As the RCD had been strapped out, the fault was feeding back onto our network.
Because of the nature of the site, we agreed to help the owner locate the fault. The whole place was an absolute nightmare.
The switch on the bottom left feeds the sub-main cable which runs up to the pig sheds. At the other end is a fuseboard with 3 fuses in, and then everything is fed out on 2.5mm2 twin and earth with unfused cooker switches used to isolate different sheds!
Needless to say, he got a severe ear-bashing and has promised to sort this mess out. I will be going back soon...
#105349 - 09/28/0405:43 AMRe: Problems with nuisance tripping
Just to point out to anyone here not yet familiar with British systems that this should be 230/240V phase-to-neutral, 400/415V phase-to-phase.
Ian, What earthing arrangement is being used here? Assuming your supply neutral is earthed securely, the only way I can figure to get the voltage readings you state a half mile away is if it's TT earthing at the farm and there's a fair amount of underground metallic pipe between the two locations as well.
By the way, what's the newer meter feeding? Separate single-phase for the house maybe? (Can't make it out from the pic, and that Marks & Spencer bag could be hiding something! ).
I guess we should at least give the guy credit for using the right phase colors on his jumpers!
#105350 - 09/28/0408:33 AMRe: Problems with nuisance tripping
The farm is on a TT system. The cable from the cut-out runs for 30m underground, then up a pole to 7 spans of aerial bundled conductor (ABC), then underground for 60m before running up another pole and along 3 spans of copper overhead.
The feed is teed off to the local transformer along the route somewhere too.
You are also correct about the newer single phase meter being for the domestic dwelling. They didn't have a trip switch in there either......
#105351 - 10/07/0410:34 PMRe: Problems with nuisance tripping