I concur with Mike. It is unlikely you could get an accurate reading to discriminate between 0.07 and 0.08 with an MFT. They are really only designed for installations to 100A, PSCC and Earth loop at higher ratings are difficult even with all the right instruments on a real installation because you need bolted connections, exactly zeroed leads and high test currents. If this is a submain as I suspect, the exact disconnection time is probably not the most important thing. If it is 6 seconds not 5, then nothing particularly bad is going to happen. Do you have the original EIC? What is the quoted figure, because if it is close, it is probably better than the one you have measured. The correct way to test this without specilised equipment is to disconnect the live conductors, substitute a high current power supply and pass say 10-50A (Measured to 1% with calibrated meters) and measure the volt drop with a high accuracy millivoltmeter. Now you have the real resistance and it will be lower than you expected. You now also take the path loop inductance into account (either by measurment or calculation having measured the cable length accurately), and calculate the series reactance. Add and that is the real loop impedance. You can use an AC current, but now adjustment and accurate measurment are more difficult (no clamp meters here!).

I concur with Mike. It is unlikely you could get an accurate reading to discriminate between 0.07 and 0.08 with an MFT. They are really only designed for installations to 100A, PSCC and Earth loop at higher ratings are difficult even with all the right instruments on a real installation because you need bolted connections, exactly zeroed leads and high test currents. If this is a submain as I suspect, the exact disconnection time is probably not the most important thing. If it is 6 seconds not 5, then nothing particularly bad is going to happen. Do you have the original EIC? What is the quoted figure, because if it is close, it is probably better than the one you have measured. The correct way to test this without specilised equipment is to disconnect the live conductors, substitute a high current power supply and pass say 10-50A (Measured to 1% with calibrated meters) and measure the volt drop with a high accuracy millivoltmeter. Now you have the real resistance and it will be lower than you expected. You now also take the path loop inductance into account (either by measurment or calculation having measured the cable length accurately), and calculate the series reactance. Add and that is the real loop impedance. You can use an AC current, but now adjustment and accurate measurment are more difficult (no clamp meters here!).