Ze reading

[mechelec]

Whats the claculation to work this out, I am interested

Cheers

Si

As far as I can understand it they work on a 5 second disconnection time to bs7671 as the cutout is usually within the property it has to comply with the regs. Check out the max Ze for bs88 and bs1362

 

[CLB]

I was reading a Napit factsheet today regarding Ze readings and on it is a diagram showing the earth disconnected from the MET with the earth lead from the tester attached to it with a croc clip, and the L and N leads/probes on the L and N terminals on the incoming supply. Isn't that testing all three wires to the supply?
I tested mine as shown and got a reading of 0.18ohms. Seems adequate enough to me.

 

[1shortcircuit]

Have you seen the date on the thread you have posted on?

Your Ze sounds fine even if it was to be a TNCS earthing arrangement.

By removing the Main Earth and testing like you explain you are indeed testing the External Earth Fault Loop Impedance (Ze ---- e = external)

Please remember that this is a LIVE test and if you are unsure of the procedure and how to perform the test correctly and what you should be expecting to see on your meter then you should be supervised whilst doing so.

Practicing is all good, killing yourself is not so good... Although considering some of the recent threads some opinions may differ lol (Just kidding )

:thumbsup

 

[Jimmy Boy]

Have I missed something ? Old thread or not, Ze is taken between between Line and the distributors Earth which is disconnected from the board/MET with the CU isolated.
The OP seems to be describing the tests PSSC and PEFC the greater value obtained being the PFC
J

 

[IQ Electrical]

Have I missed something ? Old thread or not, Ze is taken between between Line and the distributors Earth which is disconnected from the board/MET with the CU isolated.
The OP seems to be describing the tests PSSC and PEFC the greater value obtained being the PFC
J

To be fair, he's included the EFLI value at 0.46 Ohms, he just doesn't have a clue what it means or what the recommended upper limits are.
Neither BS7671 nor ESQCR regulations make a maximum limit on Ze values but there was an 'engineering agreement' to attempt where possible to use the commonly known upper limits (0.35 etc etc).

 

[1shortcircuit]

I was reading a Napit factsheet today regarding Ze readings and on it is a diagram showing the earth disconnected from the MET with the earth lead from the tester attached to it with a croc clip, and the L and N leads/probes on the L and N terminals on the incoming supply. Isn't that testing all three wires to the supply?
I tested mine as shown and got a reading of 0.18ohms. Seems adequate enough to me.

This is the part I was referring too which is discussing Ze

I think a forum search would have brought up a more recent thread to add to:thumbsup

 

[Jimmy Boy]

To be fair, he's included the EFLI value at 0.46 Ohms, he just doesn't have a clue what it means or what the recommended upper limits are.
Neither BS7671 nor ESQCR regulations make a maximum limit on Ze values but there was an 'engineering agreement' to attempt where possible to use the commonly known upper limits (0.35 etc etc).

Nor do I please explain ! ha ha
J