Sub Main Zdb Test

[DeanAlani]

Hi, this is my first post here.

I have a 3 phase board with a 40amp circuit breaker supplying a single phase board to a small office.
I understand that with the 3 phase board how to get the Ze thats not an issue. How do I test to get my Zs (Zdb) for the single phase board?

Do I link the L&E together in the 3 phase board and then test between L&E on the main breaker for the single phase board? This will give me a Zs then i add this to the R1 + R2
I want to get a reading for my Ze at DB for my sub main board on the EICR

Thanks

 

[westward10]

Use an earth fault loop impedance tester, you measure Zs at the single phase office board. No different to any other circuit.

 

[DeanAlani]

Use an earth fault loop impedance tester, you measure Zs at the single phase office board. No different to any other circuit.

Thanks - I'm really over thinking this. I have my 2391 Exam in the morning

 

[westward10]

Good luck.