How to connect the low-voltage plug and socket correctly?
Line-L (red, yellow, blue), neutral-N (blue or black) and ground-E (yellow-green)
In order to make the alternating current have a convenient power conversion function, the power transmission usually adopts the form of three-phase four-wire system. The three ends of the three-phase electricity are called the phase line, and the three ends of the three-phase electricity are connected together and called the neutral line, also known as the ‘zero line’.
The reason why it is called the neutral line is that there is no current flowing in the neutral line at the time of three-phase balance, and then it is directly or indirectly connected to the earth, and its voltage with the earth is close to zero.
In the low-voltage plug and socket, a three-phase four-wire system is used to transmit electric energy, including three-phase wires (live wires) and a neutral wire (zero wire). In order to ensure the safety of electricity consumption, the user area adopts a three-phase five-wire system for power supply. This fifth line is exactly the ground protection line (ground wire), and one end of it is deeply buried in the ground near the user’s area with a metal conductor.
The other end is connected to the grounding contact of each user to play the role of grounding protection. The grounding wire is a line that reliably connects the casing of equipment or electrical appliances to the earth, and is a good way to prevent electric shock accidents. Proper grounding can improve the immunity of the entire system.
Most of the low-voltage plugs and sockets we use are single-phase three-wire sockets or single-phase two-wire sockets. In the single-phase three-wire socket, the middle is the ground wire, which is also used for positioning. The other two ends are connected to live wire and neutral wire respectively. The wiring sequence is left zero right, that is, the left side is the neutral wire, and the right side is the live wire.
All household appliances with metal casings use single-phase three-wire power plugs. The three plugs are arranged in an orthogonal three-way arrangement, and the long and thick copper plug on the top is the ground wire. The ground wire has a special ground symbol.
The two ground wires below are the neutral wire (the symbol letter is ‘N’ neutral wire) and the live wire (the symbol letter is ‘L’ live wire), and the order is left zero and right fire. (When the back of the plug is facing you) It doesn’t matter if the AC live wire and neutral wire are reversed. Does not affect the use of electrical appliances.
It is difficult to distinguish the neutral wire from the ground wire. If the power supply has a leakage protector, plug the low-voltage plug socket into the electrical appliance. If it trips, it means that the ground wire is actually connected to the neutral wire; if it does not trip, it is correct.
Under normal circumstances, red, yellow and blue are used for the live wires of a three-phase circuit to indicate the three live wires, and black is used for the neutral wire.
In a single-phase lighting circuit, yellow generally represents the live wire, blue represents the neutral wire, and yellow-green represents the ground wire. In some places, red means the live wire, black means the neutral wire, and yellow-green means the ground wire.
Hot Blogs
How to connect the low-voltage plug and socket correctly?
Line-L (red, yellow, blue), neutral-N (blue or black) and ground-E.
High current plug and socket: do you know how to choose the switch socket
High current plug and socket: do you know how to choose the switch socket.
How to choose a low-voltage plug and socket?
Understand the safety performance of low-voltage plugs and sockets.
