IQS Newsroom Articles on Electrical Plugs
Electrical Plugs
Electrical plugs are male electrical connectors with metal-blade contact prongs that connect electrically with holes in the matching female electrical receptacle, thus allowing electricity to flow from the power supply to an electrically powered object equipped with an electrical plug. Male electric plugs generally have two or three pins or prongs that are inserted into the slots in the mating female socket. The connection between the mating male plug and female socket must be sufficiently tight in order to make a good electrical connection and complete the electrical circuit. Used in applications such as electrical power tools, lighting, sound equipment, shop equipment, refrigeration units and laptop computers, electrical plugs are utilized anywhere that electrical equipment and appliances are in use. Industries that benefit from electrical plugs include commercial, retail, residential, industrial manufacturing, electronics, construction, automotive, medical and food processing.
The male electrical plug connects the electrical receptacle, electrical outlet or power supply. Electrical plug manufacturers classify molded male electric plugs by receptacle type and voltage; most countries or large regions have slightly different voltage standards and electrical receptacle configurations which may or may not be interchangeable with power cords from other locations. The two most commonly used North American "NEMA" plug types are Type A, which have two conducting blades, or prongs of a live contact and a neutral contact, and Type B, which have an additional third grounding rod. The original Type A two-prong electrical plug was invented in 1904. The Type B three-prong plug was invented in 1928, and served to improve safety and prevent electrical shock by using a "ground" prong. Both plug types are configured with a molded plastic body called a "jack" which holds the two blades apart, while the cord connects to the blades within the plug body. The blades are typically made out of steel or brass, and are coated with zinc, tin or nickel. Inserting the blades into an electrical outlet, or receptacle, energizes the blades. Electricity then flows through the blades, the blade-cord connection and the power supply cord, providing electricity to the equipment.
Polarization and grounding are especially important for certain higher voltage appliances and electrical equipment that could have a higher risk of electric shock when they become live. Polarization of an electric plug ensures that the equipment is connected to the neutral, or grounded, side of the circuit. Sensitive electrical equipment and products should only be used with polarized or grounding type electrical plugs. An electrical plug is polarized when the physical characteristics of the blades allow the plug to be connected to the electrical outlet in only one way. Non-polarized plugs do not restrict the way the electrical plug is connected to the electrical outlet. Three-prong electrical plugs are inherently polarized, while two-prong electrical plugs do not have a grounding pin but may be polarized if one blade is larger than the other. The National Electrical Manufacturers Association (NEMA) sets the standards power cord manufacturers follow for both male electric plugs and female electric plugs. Sensitive electrical equipment and products should only be used with polarized or grounding type cord sets.