1. The line used
(1) Use a socket to connect to the power supply line, which should be covered to prevent electric shock. For example, various power sockets and power socket boxes can be seen in the factory workshop.
(2) The connection between the cables, the equipment input socket of the equipment should be plugged into the power supply, etc., the connector is selected. The connector is suitable to be connected to the end of the power supply line and has a cover to prevent electric shock.
(3) Use the plug or appliance input socket as the input interface of the electrical equipment or to connect the power receiving cable on the receiving line.
Second, consider the working environment
1. Protection performance
(1) Under general environmental conditions, such as the usual factory workshop, splash-proof plugs and sockets can meet the requirements.
(2) In harsh environments or places where water may be immersed, such as cement workshops, muddy construction sites and container terminals, etc., where there is a lot of dust or may be immersed in water, IP67 anti-immersion plugs and sockets are selected, and their protection performance can meet the requirements Claim.

2. Shell protective material
(1) Plastic. Usually the plugs and sockets are plastic shells with good performance in all aspects and can be used in general workplaces.
(2) Rubber. Black rubber shell plugs and sockets are available in coal mines.
(3) Aluminum alloy. There are some workshops with high working temperature and spark splash. For example, steel-making and iron-making workshops, casting workshops, etc. Under special industrial environment conditions, plugs and sockets with aluminum alloy shells should be used.
Third, the use of voltage, current, frequency according to the use of power equipment is single-phase or three-phase to determine the number of poles and sockets. Choose 3 poles for single-phase power supply, and 4 poles if the three-phase power supply is grounded, otherwise choose 5 poles. Then, select the corresponding specifications according to the rated voltage, working current level and frequency of the equipment. Domestic AC power grid is generally three-phase 380V, single-phase 220V, frequency 50Hz