Hi Paul,
Thanks for your quick response. I am actually interested in the lowest fault current for earth loop calculations. You see I would agree with your good self but a seior and may I say well respected engineer in the power company insists that this is effectively a Thenevin equivalent circuit and thus the fault will experience the open circuit voltage.
I measured 190v at the terminals of a pme single phase installation. This voltage varies over time. The Zs of some circuits is close to maximum tolerable values and such voltages give me cause for concern. Now I know that it is not the terminal voltage that drives the fault current but I am convinced that the upstream loads will affect the value of earth fault current?
