Looked at an existing install for a friend of client of mine. They had solar inverter installed with with mains supply for when the sun isn't shining. Basically when the sun is shining the solar panels charge the batteries, if the sun is not out the mains charges the batteries (after load shedding). The power goes to a sub DB (from the man DB) in 6mm flat twin and earth, through 30 amp breaker to the inverter and back to the sub DB through an earth leakage before going to 4 x 20 amp circuit breakers feeding 2 sockets each. The earth leakage sometimes trips, even when nothing is plugged in. The socket circuits were tested (earth, ins res, polarity) and all good, I tested the earth leakage to see if was oversensitive and it didn't trip. I found that the voltage coming out of the inverter to the earth leakage is 230 L-N, 180 volt(+/-) L to E and 50 volt(+/-) N - E. Even when I completely disconnect the out going cables from the inverter I still get these unusual voltages at the out put terminal of the inverter. I have triple checked with 3 different meters (2 major techs and a fluke 1653B) and still the same. The neutral bars are separate in the sub DB, one for the supply into the DB and supply out to the DB the other for the earth leakage protected circuits.
If I do a Earth leakage test it doesn't trip when in the sub DB, which is because of these strange voltages. If i take the same earth leakage and test at my own home, it trips at 24mA perfectly.
Contacted suppler and suggested that I link Neutral and Earth of the out going terminal and install an earth spike on the outgoing side. This sounds like a very bad idea to me. I get linking N and E on a generator but that operates when the the supply is completely disconnected via change over switch
I have never had this before from an inverter. Surely should be 230 L - E, 240 L - N and pretty much 0V N -E
What do you guys think, faulty inverter?