How to detect whether it is a short circuit or grounding
But I will still answer the question on how to detect whether the distribution line of the knife switch without circuit breaker and residual current circuit breaker protection is short circuited or grounded; (Actually, if there is a short circuit in the circuit of the knife switch distribution, the consequences are either burning out the wires or damaging the knife switch. However, I will still answer the question according to the detection principle.).
(1) Turn off the power switch at the beginning of the distribution line, disconnect all load switches on the line, including the plug-in load connected to the socket, and use a multimeter to measure the resistance of the two outgoing lines of the power switch in 100 levels. If the resistance of the multimeter is very small (i.e. the pointer swings to the right almost to the end), it proves that there is a short circuit between the phase line and the neutral line. Otherwise, there is no short circuit. The same detection method is used to measure whether there is a short circuit between the phase line and the protective grounding (neutral) line, and between the neutral line and the protective grounding (neutral) line.
(2) If there is no short circuit between the phase wire and the neutral wire, the phase wire and the protective grounding (neutral) wire, and the neutral wire and the protective grounding (neutral) wire, then it is possible to detect whether there is a grounding phenomenon between the phase wire and the neutral wire.
If you have a clamp meter on hand, it is best to use a clamp meter to detect the grounding current. The detection method is: first disconnect the power switch, remove the distribution neutral wire from the power switch output terminal (and make a mark), then close the power switch, and use a clamp meter to measure whether there is a grounding current in the phase wire (the clamp meter is first set to 100A if no current can be measured, and then slowly set to a smaller current level). If the grounding current still cannot be measured; You can exclude the grounding of the phase line. After checking the phase line, disconnect the power switch and remove the phase line, connect the neutral line to the phase line outlet contact of the power switch, close the power switch, and use the above clamp meter to measure the phase line to check the neutral line.
If you don't have a clamp shaped watch on hand; You can also find a hanging lamp head and a 25 watt incandescent bulb, install the lamp head, and connect two 15 centimeter wires for backup. The detection method is:; Disconnect the power switch, remove the phase wire and neutral wire, first connect the lamp head and bulb in series between the phase wire and the phase wire outlet contact of the power switch, take safety measures, and then close the power switch. If the bulb lights up at this time, it proves that the phase wire is grounded. The higher the brightness of the bulb, the greater the grounding current, and vice versa. If the bulb does not light up, the grounding of the phase wire can be ruled out. After checking the phase line, disconnect the power switch, remove the phase line, connect the original bulb in series between the neutral line and the phase line connection point of the power switch outlet, and also take safety measures. Close the power switch to check the neutral line, and the test result is the same as the above phase line.
