The plug and socket are something that we have used a million times in our lives. The plug and socket have been a historical discovery. Today we plug different types of electrical appliances in the socket easily without much risk. However, has it always been so simple and safe? No.

In earlier times, people use to plug in electrical appliances with mere open-ended wires. Sometimes even with incompatible plugs! Today almost each country in the world uses its specific standards for plugs, sockets, and power cords. So how is the installation of electrical appliances in the sockets today with negligible risks?

Answer is simple!

Using Power Cords. Power cords are the line cable or mains cable. It is this cable, which bears the burden of temporarily connecting a portable electronic appliance with the main electrical supply line. It makes this possible by the attached pair of connecting couplers on its either ends.

These connector power cords are detachable from the mains supply line and the Electrical appliances. Power cord is a flexible and an insulated conductor having one male and one female connector attached at its either end. All these power cords and its coupler designing by the manufacturers across the globe are on the preset standards set by the International Electrotechnical Commission (IEC).


Back in 1926, the establishment of National Electrical Manufacturing Association (NEMA) in North America took place. It developed NEMA 1 connector. Today NEMA power cords are in use all over North America and in countries, which have specified the NEMA standards. Other countries have created their own set of power plug standards. It can destroy the appliances, if these are in use with unmatched power supply.

NEMA Power Cords

A basic NEMA connector has two pins or flat prongs, which are almost 5 inches apart from each other; it is the NEMA type 1. If it also consists of a round pin or prong right below the two flat prongs, NEMA type 5 is its name. A “grounded plug” uses a third pin for grounding purposes.

Safety Measures

There are many variants of the NEMA plugs available in the United States and North America but NEMA type 1 & type 5 are the most common among them. Some NEMA plugs undergo polarization. These plugs need a special attention when plugged in the socket.

If not installed in a specifically instructed manner, it can destroy the appliance. To avoid this kind of an accident, its design is such that the specific prong of the plug fills a specific hole of the socket. Hence, these types of NEMA plugs have two flat pins of unequal length.


The main classification of NEMA devices includes straight blade and locking. In the household consumer goods consisting of electrical appliances, Straight blade is evident. The locking NEMA power cord is in use for the major industrial applications.

Straight blade has a design such that detaches it swiftly and the latter has a design such that it does not detach easily from the receptacle. A receptacle is a device mounted on an electrical appliance where the external power cord attaches.

The curve blade of the locking type of NEMA cord allows the plug to entwine and lock into the receptacle. The letter L preceding the NEMA code identifies the locking conductor.