Ze readings >2000Mohms

[bennie]

So basically a Zdb is a Zs reading for an outgoing distribution board. Which clears up the misunderstanding with some of the previous comments.

Is there a reason / requirement why the engineer is telling us to disconnect main incoming supplie earthss for every Sub DB?

Not that I can think of. I take it the DBs are supplied by SWA or conduit or trunking with singles? Either way that DB and all the CPCs in it will still be connected to the main earth via parallel paths so taking the earth out will not make much of a difference and like I said the only test carried out with the main earth disconnected is the Ze test.

 

[ELECELEC]

Not that I can think of. I take it the DBs are supplied by SWA or conduit or trunking with singles? Either way that DB and all the CPCs in it will still be connected to the main earth via parallel paths so taking the earth out will not make much of a difference and like I said the only test carried out with the main earth disconnected is the Ze test.

Yes all cables used are SWA.

 

[bennie]

Yes all cables used are SWA.

Your tester is obviously picking up something that's stopping it carry out the test. If you've checked the leads & the tester settings and all is good then you might want to check for loose neutral & earth connections and test for voltage between N & E. If all your there to do is give them Ze/Zs/Zdb results then you've done that, may be people have just made them up in the past. They might need to pay for further investigation.