Ground Resistance Testing IT System

[rig-electrician]

Question here we have been discussing can you perform a ground resistance test with a clamp on meter on an IT (Insulated form Earth) system with no Neutral. I am thinking that the answer is no since there is no return path for the induced signal to return on.

[SecondGen]

Question here we have been discussing can you perform a ground resistance test with a clamp on meter on an IT (Insulated form Earth) system with no Neutral. I am thinking that the answer is no since there is no return path for the induced signal to return on.

You are correct. The clamp-on tester is only effective in situations with multiple grounds in parallel. It cannot be used on isolated grounds, as there is no return path. In addition, it cannot be used if there is an alternate lower resistance loop not including ground.

Clamp-on testing requires a good return path, is susceptible to noise, has reduced accuracy and cannot be used on isolated grounds. It is not applicable for installation checks or commissioning new sites and has no built in proof.

Would recommend "Getting Down to Earth" by Megger to anyone who is interested in reading up more on the topic. https://portalvhds963slh4m3fqg2.blob.core.windows.net/megger-products/GettingDownToEarth.pdf