Anyone know how to get ZE from Scottish Power ???

None of these are really the way to “measure” this Ze. It is best done by the analysis I suggested above, the resistance to the N - E link. Any suggestion that this has anything to do with real “Earth” is illusory. Does anyone remember the definition of a Ze value, or the Earth loop? 313.1 and page 41 (BS7671:2018).

In reality, it does not matter what the value is, it just needs to be low enough to ensure disconnection of an Earth fault at whatever the current level CAN BE at a particular point in the installation. Close to this supply transformer it can be very high indeed, further away the current falls rapidly due to cable resistance, and this is why the N-E link may be at the local switchboard. A short at the transformer will be protected by the HV CPD, at perhaps fuses or circuit breakers of about 20 or 25A for a 500 kVA TX. The primary current will be about 15A at full load, the secondary about 750A. Pro-rata obviously for larger transformers. You can easily calculate all these yourselves, it's not rocket science. The transformer short circuit current is set by the winding resistance and leakage reactance, both available from the manufacturer data.

None of these are really the way to “measure” this Ze. It is best done by the analysis I suggested above, the resistance to the N - E link. Any suggestion that this has anything to do with real “Earth” is illusory. Does anyone remember the definition of a Ze value, or the Earth loop? 313.1 and page 41 (BS7671:2018).

In reality, it does not matter what the value is, it just needs to be low enough to ensure disconnection of an Earth fault at whatever the current level CAN BE at a particular point in the installation. Close to this supply transformer it can be very high indeed, further away the current falls rapidly due to cable resistance, and this is why the N-E link may be at the local switchboard. A short at the transformer will be protected by the HV CPD, at perhaps fuses or circuit breakers of about 20 or 25A for a 500 kVA TX. The primary current will be about 15A at full load, the secondary about 750A. Pro-rata obviously for larger transformers. You can easily calculate all these yourselves, it's not rocket science. The transformer short circuit current is set by the winding resistance and leakage reactance, both available from the manufacturer data.