May 23, 2016 · Maybe once a month the circuit breaker trips when no one is using either room. We had the circuit breaker replaced in the panel. But guess what, it tripped again a few days ago. Upstairs is a TV room with a surge suppressor, TV, stereo, etc. Downstairs just a few lamps and clock radio plugged in. An earth leakage or dead short is the most common causes of RCD and fuse trips, which may occur each time you switch the appliance on. Working with some appliances, you realise that they trip conditionally; when using specific functions.Feb 15, 2017 · The problem with a MCB is it only turns off the line, the neutral is left connected. So start putting the MCB's in left to right and the last MCB on right may trip the RCD, but start putting the MCB's in right to left and the last MCB on the left can trip it. It is just the last MCB just puts it over the limit. Jan 26, 2004 · Actually, it's 8 ga. for a 40 amp double pole breaker and 6 ga. if using a 50 amp breaker. Running 6 ga. to a 40 amp could cause the breaker not to trip and running 8 ga. to 50 amp could cause wire overheating.