Good morning Dave.

On my way back to site now.
Some more testing to do.

Theoretically, a bridged neutral and earth on the load side should cause the ELR to trip if there's a load present, not prevent it from tripping, which is the case here.. That's the confusing part.

Hopefully, later today, I can give some feedback.

Like I said, it's a first for me, so it's one of those occurances which I am sure doesn't rear it's head too often.