there are few suggestion with the trouble shooting Dave55,,
one is check the starting current and running current if 400 watts MH CWA ballast the starting current useally lower than running current btw ,,
second thing you can do is check the breaker to see how much inrush current during start up if not very high maybe the breaker is weak from all the abuse of inrush current there and there is a breaker that can dealt with high inrush current assocated with HID or transformers in the circuits
the other thing you can do is put the indivual fuseing for each lumiaire but that will drive up the cost for time and materals
hope this can help you with some question you are asking this one dave
Merci , Marc
