A 1.5kW motor single phase is tripping the 30mA RCD protected sub dis-board out on a construction site. The installation is new, tested and clear. What's the cause, and do I need to call the motor-people out to sort out the motor? I thought it might be the armature going to earth or similar. Cheers
It's probably something to do with the switching-on of an inductive load, like a motor, that can trip an RCD. Not sure how you would get over this problem. If switching is double-pole that may help. Ideally a motor of that size shouldn't be run through a normal 30Ma. RCD. It's either some sort of imbalance to the supply caused by the motor switching on, or it's deforming the mains frequency wave-form somehow, and that can cause unwanted tripping. There is I believe, a special type of RCD that can handle this. There is a post somewhere on this forum and link, that explains this. Perhaps a "type S" time-delayed RCD at the mains and then seperate the motor off of the rest of the wiring, which can be protected with the usual type of RCD. JS
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