In the case of a total power disconnect, find a wire that can be connected from the home outlet to the ground of the main distribution box. One end of the line is connected to the grounding line at the total incoming line in the distribution box of your home. The other end of the line is connected to a test pen on the multimeter. The other meter of the multimeter is used to detect the grounding end of the socket. The standard connection method is the left hole zero line, the right hole fire line, and the upper hole ground.
The multimeter is adjusted to the minimum position of the ohm file. If the measured resistance on the meter is not more than 4 ohms, the grounding is normal! If the wiring of the socket is not standardized, the position of the live and neutral jacks needs to be newly determined.
In the case of voltage on the socket, adjust the multimeter to the AC voltage file. Assume that the socket is connected according to the standard connection, left zero, right fire, grounding, first measure the voltage of the left and right holes, and then measure The voltage on the left hole and the upper hole is normal if the voltage of the left hole and the right hole is slightly larger than the voltage of the left hole and the upper hole within 5V. Live operation, pay attention to safety.