Put the multimeter in the R×1 resistance bracket and reset the ohm to zero.

(2) Place one of the multimeter's watch pens on the wire inlet end and the other on the wire end of the socket. Put the leakage protector and the air switch of the socket circuit in a closed state in turn, and read the resistance value should be approximately equal to zero. If the measured resistance is large, it may be a bad contact somewhere and needs to be checked. If the resistance is infinite, it may be a circuit breaker that needs to be checked.

(3) Place one of the multimeter's watch pens on the fire line inlet end and the other on the fire line end of the lamp holder. Put the leakage protector and the air switch of the lighting line in the closed state in turn. Read out the resistance value should be approximately equal to zero or infinity. If the measured resistance is large, it may be a faulty contact somewhere in the fire line, which needs to be checked. If the resistance is infinite in whatever state the switch is in, it may be a circuit breaker that needs to be checked.
Place one of the multimeter's stylus on the zero line inlet end and the other on the zero line end of the socket, put the leakage protector in the closed state, and read the resistance value should be approximately equal to zero. If the measured resistance is large, it may be a bad contact somewhere in the zero line, which needs to be checked. If the resistance is infinite, it may be a circuit breaker that needs to be checked.
Place one of the multimeter's watch pens on the zero line inlet end and the other on the zero line end of the lamp holder, put the leakage protector in a closed state, and read the resistance value should be approximately equal to zero. If the measured resistance is large, it may be a bad contact somewhere in the zero line, which needs to be checked. If the resistance is infinite, it may be a circuit breaker that needs to be checked.
Place one of the meter's watch pens on the ground wire into the end, and the other on the ground wire end of the socket, and read the resistance value should be approximately equal to zero. If the measured resistance is large, it may be that the ground wire is in bad contact somewhere and needs to be checked. If the resistance is infinite, it may be a ground wire break that needs to be checked.