Testing the Ze of an electrical installation

Have I got a connection to earth?
How to carry out a Ze test
A vital test that confirms if the electrical installation has an external connection to earth

[@andybrown3653]

Apart from anything else, your graphics are fantastic and very clear. You need more followers..

[@JPElectric]

Thank you Andy

[@fairisfairfairisfair9788]

Another excellent video, with great visuals. Very grateful 🙏

[@tommytar222]

keep the coming. can you cover 16mm cables and flats

[@garylatto4191]

When doing zdb, am I correct you compare the results to a zs ie zs required for the size of protective device ? Thanks 👍

[@jonerasmus9399]

Good

[@JPElectric]

Thanks Jon

[@antonwillis896]

Thanks for the vid. On a 3 phase system I test across earth to each phase do i then test N to each phase also? And then I have to double the highest reading? I’ve confused myself and my am2 is tomorrow

[@JPElectric]

The Ze test for three phase is just between each phase and the disconnected earthing conductor ( DB isolated)
The highest reading would be your Ze..
Remember to reconnect the earthing conductor as soon as you finish the test.
By what you describe I presume you mean a PFC test.
Yes you need to test to see what is the highest possible fault current that can flow between conductors.
So you need to test
Earth to each phase .
Neutral to each phase.
But we also need to know what is the fault current that could flow between phases...
Testing between phases is often discouraged as this will provide the highest fault current, and some testers could not handle it...( but it depends on what training you are doing, I am sure you will have gone through this on your course)
So, to err on caution the highest measurement taken when testing between each of the 3 phases and neutral you would double,and use that as a guide for you phase to phase fault current. So you do not need to test between phases
Remember you safe isolation though.....
For safe isolation on 3 phase its 10 tests
L1 and L2
L1 and L3
L1 and Neutral
L1 and Earth
L2 and L3
L2 and Neutral
L2 and Earth
L3 and Neutral
L3 and Earth
Neutral and Earth

[@fairisfairfairisfair9788]

What does zdb mean by the way?

[@JPElectric]

Hi FairisFair, Thank you for your kind comments on my videos. Zdb is the Zs reading at a distribution board. The Ze is at the origin, any other boards would have a Zdb measurement. So the Zdb would take account of the Ze and the impedance of the cable feeding the distribution board.

[@pcg1276]

Is Zs= Ze + (R1+R2) or Zdb + (R1+R2) at DB2 .thanks

[@JPElectric]

Hi Pcg 127 You only have one Ze and thats at the origin. Any subsequent boards will be your Zdb (your supply to the board. Then you would ad on you R1 + R2 to get the Zs.

[@pcg1276]

@@JPElectric so the measured impedance of a circuit in db2 would be Zs= Zdb + (R1+R2)