Color identification of internal circuit of industrial plug:1. Red live wire (L), dark blue zero wire (N), half yellow and half green as grounding wire. Industrial plugs are applicable to industry, generally divided into 3-core, 4-core, 5-core, etc. Current is generally divided into 16A, 32A, 63A, 125A, 250A, 420A, etc. The protection level can be divided into IP44 and IP67, which are relatively conventional. Generally, it is used with industrial sockets and connectors. IP54, that is, dustproof level 5: it cannot completely prevent dust intrusion, but the amount of dust intrusion will not affect the normal operation of the product; Waterproof grade 4: prevent splashing water from invading, and prevent splashing water from all directions from invading. The power socket has a seat into which one or more circuit wires can be inserted, through which various wires can be inserted to facilitate connection with other circuits.2. The effect of the three-wire industrial plug is to strengthen the safety of electrical products with metal shells used by workers, and to prevent accidents caused by electric shock during the whole application process.3. Three kinds of zero-point live wires with different phases, each of which is 380 volts in the middle of the working voltage. It's used in power plants. Generally, the single-phase switching power supply system is used for electrical products, and its three wires are the live wire zero line, the zero line (neutral point) and the ground line, and the zero line between the live wire zero line and the working voltage is 220v, so it is not three-phase electricity.4. Its plug and socket are not three-phase plugs and sockets (single-phase three hole socket). There is an additional grounding wire, in order to ensure safety (in the neutral point ungrounded system, you can choose grounding protection; In the neutral grounding system software, zero protection must be selected).Three-hole industrial plug: "Left Zero Right Fire Ground" (the ground wire is generally connected with the buried metal sheet), as shown in the following figure. Three-wire plug: Most high-power electrical appliances with plastic shells are three-wire plugs, which are equipped with three hole socket. The function of the grounding device: the middle plug of the three-wire plug is connected with the plastic shell of the high-power electrical appliance, and the plastic shell is connected with the ground when inserted into the three hole socket.Industrial plugs are 220v power plugs for household appliances. The internal wiring method should be properly wired according to the international and national industry standards, that is, "left zero, right fire, middle zone". If the internal wiring of the three-wire power socket is incorrect (which may occur during indoor decoration or irregular welding machine installation), when the customer plugs into the equipment, the light can't work normally, which will lead to the induction and electrification of the housing of the household appliance, which will cause the danger of electric shock.When installing the three-wire industrial plug, it can be connected according to the drawing. Firmly insert the industrial plug and wiring to determine which (color) is the phase line (zero point of live wire) and which is the neutral line (zero line) and ground wire. International Electrotechnical Commission requires that light green transmission lines be used for maintenance grounding wires (in Japan, some European goods use a single emerald green as maintenance grounding wires). The white transmission line is the center line (zero line), and the bright red transmission line is the phase line.