How to use a multimeter to measure the circuit before power is supplied
The lights and panels have been installed on the construction site. How to use a multimeter to measure if there is a problem with the circuit before power is supplied? To ensure that the wire panel lights are not burned out during power transmission.
The first step is to confirm whether the rated voltage of the lamp is consistent with the voltage at the power supply point. Use a multimeter to adjust the gear to AC voltage of 500 (600) V and measure the voltage at the input terminal of the power supply point (switch) to determine whether the voltage is 220V or 380V. Generally, the rated voltage of the lamp is 220V. If a voltage of 380V is applied, the lamp will burn out;
Step 2: Before powering on, use a multimeter to adjust the output terminal of the power supply (switch) to the diode position to measure whether there is a short circuit in the power supply circuit of the lamp. If a short circuit occurs, the resistance value is generally between 0 and a few ohms (000-010), and this needs to be confirmed and tested in the next step. If the value is a few thousand ohms or infinity, it can be ignored;
The third step is to confirm the voltage of the lighting fixture and that the circuit is not short circuited before powering it on (closing the switch). If the lights controlled by the power outlet (switch) do not light up, it is necessary to check that the common wire at the end of the lighting fixture is disconnected. After cutting off the power, open one of the wrapping points at the common end (common grounding point) and disconnect the circuit, paying attention to the wire end not touching anything else. Then turn on the power and use a multimeter to adjust the AC voltage to 500 (600) V. You can use a black meter to ground and a red meter as a probe to measure the two ends of the disconnected circuit. If the multimeter displays a voltage of tens of volts or more, the test indicates that the circuit is not disconnected. If there is no voltage at both ends during testing, it is necessary to cut off the power. Swap and connect the two wires of the electrical circuit (switch) before measuring. It is better to have a voltage end circuit, and if there is no voltage end circuit, there will be an abnormality. The former is suitable for measuring the continuity of 380V circuits, The latter is suitable for measuring the continuity of 220V power lines; If only local lighting fixtures are not lit, recheck the wiring and power output connections of the lighting fixtures.
