Electrical Outlet Types of North America

Most important in the classification of outlets is voltage and the amperage they are suited for. By these features there are four main types of outlets:

120 V, 15 Amp, NEMA 1-15
120 V, 20 Amp, NEMA 1-20
220-240 V, 15 Amp, NEMA 2-15
220-240 V, 20 Amp, NEMA 2-20

In the United States the most widely used type of outlets is 120 V, 15 Amp, although some electric devices require outlets for higher voltage and/or higher amperage. These requirements are usually linked with the power consumption of electrical devices. Since lights use little power, they can safely be on an 120V 15A outlet, while power-consuming devices such as an electrical heater may require outlets with higher amperage or/and voltage to work safely.

The plug connectors are classified according to the NEMA naming convention. NEMA is an acronym for the National Electrical Manufacturers Association.

NEMA Nomenclature

The NEMA classification breakdown:

Straight Blade or Locking
- Straight Blade (non-locking connector)
  - NEMA 1
  - NEMA 2
  - NEMA 5
  - NEMA 6
  - NEMA 10
  - NEMA 14
  - NEMA TT-30
- Locking (twist lock connector)
  - NEMA L5
  - NEMA L6
  - NEMA L7
  - NEMA L21