25 ohms Zdb + same reading for all circuits

[westward10]

Is it earthed by way of the cable sheath if so can you direct Ze to the sheath.

 

[Aaron b]

I had some silly Zs readings once and I just hadn't zeroed the meter properly. Were the R1+R2 readings done with the same probes?

 

[7029 dave]

When you took Ze did you disconnect the main earth lead away from the installation. We dont want parallel paths.

 

[pc1966]

I had some silly Zs readings once and I just hadn't zeroed the meter properly. Were the R1+R2 readings done with the same probes?

They could do "Zs" with N & E probes both to the N and should get the same for PFC and PSCC and it should be in keeping with the supply rating.

So you would expect, say, no more than 10% DNO side drop at the fuse rating, so 600A PSSC or above, hence "Zs" measured that way should be around 0.4 ohm max.

 

[pc1966]

When you took Ze did you disconnect the main earth lead away from the installation. We dont want parallel paths.

Agreed, but high Zs means either nothing useful in terms of parallel paths to the true Earth vis service pipes, etc. Or the meter (or its probes) is borked!