A typical non-rewireable two-core AC power cord plug has an internal structure that includes: a plastic housing (usually made of PVC or flame-retardant ABS), two metal prongs (often made of brass or phosphor bronze with nickel plating), the live and neutral wires inside the power cord, and the crimped or soldered connections between the prongs and the wires. A three-core plug adds a grounding prong connected to a green-yellow earth wire.

The working principle is very simple: when the plug is inserted into a socket, the live prong contacts the live spring contact inside the socket, and the neutral prong contacts the neutral contact, forming a closed circuit. Current then flows through the wires to the appliance. The grounding prong provides a safe discharge path in case of appliance leakage, protecting personal safety. During manufacturing, key quality points include the robustness of the connection between the prongs and wires (to prevent loose connections and overheating), the dimensional accuracy of the prongs (to ensure proper insertion and withdrawal force), and the sealing and fixing of the internal wires by the molded housing. High-end plugs may also incorporate built-in fuses or surge protection components, but ordinary plugs have no additional features.