What Is a Power Cord? | Mains Cable Basics Explained

A power cord is a detachable cable that supplies AC electricity from a wall outlet to a device, matching specific voltage, current, and connector standards.

When your monitor, printer, or desktop PC needs juice, the flexible cable linking it to the wall is the power cord doing that job. Also called a line cord, mains cable, or AC power cord, it delivers electricity from the building’s outlet to equipment designed for temporary connection rather than permanent wiring. The cord terminates with a plug on the wall end and a connector or bare wires on the device end, depending on what it feeds.

How a Power Cord Works and What’s Inside

A power cord carries alternating current from the mains supply to your equipment. Inside the insulated jacket, you’ll typically find two or three conductors: a live (line) wire, a neutral wire, and often a ground wire for safety. The ground pin on the plug connects to that third conductor, protecting you if a fault occurs inside the device.

Construction varies by application. Moulded connectors are common on consumer gear, while industrial or replacement cords may use hand-wired terminals. On the device end, you might find a standard receptacle, a device-specific connector, or exposed conductors meant for hardwiring.

Standards, Plug Types, and Ratings You Need to Know

Compatibility isn’t about the plug fitting the socket — it’s about matching electrical ratings and connector families. The international standard IEC 60320 defines non-locking appliance couplers for cords rated up to 250 V AC and 16 A. In the U.S., computer and IT equipment commonly uses a NEMA 5-15P plug on the wall end paired with an IEC 60320 C13 or C19 connector at the device.

Plug shapes differ by country, and so do their ratings. Choosing a cord means identifying your destination country, the required amps and volts, the number of conductors, and whether a connector is needed on the device end.

Safety and Compatibility: What Can Go Wrong

A cord that physically fits isn’t automatically safe. The voltage, current, connector type, grounding requirement, and country plug standard must all match your device. Ignoring the amperage and voltage labels on the cord limits the load it can safely supply — exceeding those ratings risks overheating.

Grounding deserves special attention. Some plugs include an earthing pin, and omitting ground on equipment that requires it creates a real safety hazard. Cord construction matters too: industry guidance referenced in NEC-related notes says the grounding conductor must be at least the same size as the other conductors and no smaller than 18 AWG, with larger sizes required for longer cords.

Mixing connector families is another common error. The C13, C19, C5, C7, and C15 device-end connectors all look similar but serve different current ratings and equipment types — verify the inlet on your device before buying. And don’t assume a “universal” cord works everywhere; plug shapes and electrical ratings vary by region, so a cord meant for one country may not be safe or legal in another.

When you need a replacement for a fridge, washing machine, or other heavy appliance, the specific cord matters even more. Our tested roundup of the best appliance power cord options breaks down which models handle the current, grounding, and connector needs of major household gear.

One last mix-up worth flagging: a power cord is electrical hardware, while a power chord is a music term. They sound alike but have nothing in common. Interpower’s guidance for selecting cords emphasizes planning ahead — identify the destination, the load, and the connector before you order, and you’ll avoid most of the problems that come from grabbing whatever fits.