how to find where is trip place of the machine

Some times when you switch on the machine, the power ideateliy trip, if this happened, what will you do: 1 check if the netural cable connect to the ground. 2 check if the insulation of the bracket, if there got wet or not, blow with hotair, and make it dry, try again. 3 switch off all the switch, then switch on the main power first, then one by one to switch on the switch, check and find out which is the problem.