Faac C721 + 4 Photocells Tripping House Power - Transformer or Wiring Issue?

Hi, I have installed a FAAC C721 with 4 photocells and everything we connect the transformer it trips the power in the house. We have tested and we get 250V but cannot understand why it keeps shorting the circuit. The C721 is just sat on driveway can't get around it. Has anyone noticed problems with this before - the transformer could just be a smoke screen it's brand new only a couple of weeks old. FAAC have said send it back for testing but that's a nightmare with all the blockwork settled back in. I have the nylon racking off also. Any help would be grateful.

What is tripped GFCI / RCD or over current?
if 1 check ground fault
if 2 you can put light bulb (incandescent and rather big) in series or some current limiter like space heater, electric kettle and then try to find out where to much current flow.