Why do you use a multimeter to measure the zero line and ground wire?
The normal zero line with ground wire is not the zero line is tapped from the neutral point of transformer, wire from ground tap buried underground, but in actual use, line five wire three-phase voltage is 380 volts, the zero line and ground wire is not feasible, because there is a 220 volt single-phase equipment on the trip, will, 220 volts three-phase five wire circuit, because the zero line is rarely used, so the wiring, the zero line and ground line together.
According to the national standard GB50054, the grounding type of low-voltage power supply and distribution system has TN system (three systems inside), TT system and IT system.At present, the general building adopts the TN - C - S system, and the N line and the PE line are connected.
1, multimeter switch to the AC voltage range, should be so multimeter has such a function,2, range from 200mV~750V, the general 200V file, some clamp type table no 200V file can choose a bigger range, the pointer multimeter stalls to dots can choose 10 V ~100V 3, and then the probes were inserted in V /COM (Jack 220V voltage measuring everyday appliances)4, the black pen line around the left circle (see Figure 2-3) of course, the more the better, pay attention: this black pen needle do not touch hands, to prevent electric shock5, right hand with the red pen were measured in the zero line or line, you write down the results of the 2 measurements, the small FireWire, zero line.
