Ze readings >2000Mohms

[ELECELEC]

Sorry, I've read all this but I still don't understand why your disconnecting the earth at each DB to carry out the test. What cable type of cable is supply them? And are you turning the DBs off before you carry the test out? Also are you reconnecting the earths before you move on to the next test?

Requirement for the Power station is that every distribution board must have a Ze reading captured - Zs readings captured on outgoing circuits.

Ze - The value of Ze is measured at the intake position on the supply side with the earthing conductor disconnected.

The main isolator / MCB is always turned off before disconnecting the supply earth, thus no outgoing circuits are energised from the DB.

Yes lol, if the earths weren't being reconnected after testing, I'm pretty sure we would all be down the road!

 

[bennie]

Requirement for the Power station is that every distribution board must have a Ze reading captured - Zs readings captured on outgoing circuits.

Ze - The value of Ze is measured at the intake position on the supply side with the earthing conductor disconnected.

The main isolator / MCB is always turned off before disconnecting the supply earth, thus no outgoing circuits are energised from the DB.

Yes lol, if the earths weren't being reconnected after testing, I'm pretty sure we would all be down the road!

Are all the DBs connected directly to the main panel or are they sub DBs fed via another DB?

 

[ELECELEC]

Are all the DBs connected directly to the main panel or are they sub DBs fed via another DB?

For this case :

Main Distribution Board Feeds - 3 Lighting DB's
- 2 HVAC DB's

 

[bennie]

Have you tested N to E to see if there's voltage with everything on. If it's to high the fluke testers will show the reading your getting. And the test your doing is for the Zdb not Ze. Ze is only done at the main incomer and it's the only test that needs the main earth disconnected. You've got 5 sub DBs so your going to have a lot of parallel paths.

 

[ELECELEC]

Have you tested N to E to see if there's voltage with everything on. If it's to high the fluke testers will show the reading your getting. And the test your doing is for the Zdb not Ze. Ze is only done at the main incomer and it's the only test that needs the main earth disconnected. You've got 5 sub DBs so your going to have a lot of parallel paths.

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?

 

[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.