Extraneous bonding

[Wolfiesmith]

Hi, I’ve been asked to test the structural steelwork of a factory to determine if bonding is required and have been trying to establish a resistance at which the cut off would be between the MET and the steel work using a wonder lead to test it? Also as the installation is existing and I would be unable to disconnect the earth bonding during working hours is this even a reliable test to carry out?

 

[Fleeting]

Probably wasting your time. The chances of it being free from conductive parts of the electrical installation is probably zero especially if the steelwork is the main structure as opposed to a small "floating" part.

 

[Andy™]

if it goes into the ground then its almost always extraneous. so much so that it can be used as an earth electrode