Hi all. Just after some advice please just in case i can fix this. On a few occasions i have come to switch my internal garage light off it has caused the garage consumer unit main breaker to trip. I have the lights on a duel circuit, i can switch them off and on at either end of the garage. I have six lights in total on six switches at the back of the garage and two at the front of the garage. It doesnt matter which light i switch off and doesnt matter if i am at the front or back of the garage. The garage consumer unit trips out. Light switch at front of garage i can switch two lights on, one at front of garage and one at back if garage. The switches at back of garage can switch these two lights on and off as well as the other 4 lights. The lights are fluorescent single tubes. The fuse boxes have been installed by a qualified electrician and tested on install. Now out of guarantee . I suspect its just a power surge as doesn't do it all the time? Or is there something wrong or do i need higher values of mcb in the fuse box in the house or is it a faulty garage rcd unit? House supply fuse to garage is a mcb rated at 40. This does not trip out. Garage fuse box rcd says 63A 30 ma 240volt This is what keeps tripping out. the lights mcb on this unit does not trip out. I have tested the garage rcd by pressing the test button and it works fine . Think might have to get electrician out if not a simple fault? any advise welcome.