Using household distribution box, a trip, so we can look at home have "socket" loop "soft breakdown" phenomenon. After such judgment method is in power, with 500 v shake table check "zero line" and "fire" between the insulation, the insulation resistance shall not be less than 0.5 ohms. There is, will you home "socket" loop "zero line" and "fire" get off, then access the same arbitrary distribution in another capacity switch, if after closing the switch trip, no longer "outlet" is your home circuit have the slight leakage phenomenon. If the switch is trip after closing, that is "outlet" loop in the home has "soft breakdown" phenomenon. Then, would be "socket" loop check home if there is a problem of leakage protection switch.