Testing ze at the origin

[Andy78]

Why would you want to rethink? Are you referring to the fact that the fault current under short-circuit conditions in a 3-ph system is significantly higher than the line-earth fault current?

What that guy said ^

 

[GB.Kayak]

No mate, it is because PEFC is taken with all bonding conductors and CPCs connected, Ze is taken with the Earthing conductor disconnected from the rest and measured on it's own.

PSSC is a different measurement.

In principle then, the earth loop resistance with the earthing conductor connected may be lower due to parallel paths; therefore, the PEFC may be higher. The same measurement configuration for the meter, but 2 different configurations for the electrical installation. Ze without earthing conductor connected, and PEFC with the earthing conductor connected!

Hope that is correct, thank you for refreshing my memory or correcting my understanding!

 

[joel89]

I passed the practical and failed the theory so have to do a re-sit doh !

 

[Risteard]

No mate, it is because PEFC is taken with all bonding conductors and CPCs connected, Ze is taken with the Earthing conductor disconnected from the rest and measured on it's own.

PSSC is a different measurement.

Indeed, and the Prospective Fault Current (PFC) is the greater of the PEFC and the PSSC. It's amazing that people think that PFC is synonymous with PEFC or PSSC. (Not directed at you as you clearly understand the difference!)