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.
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
- Straight Blade (non-locking connector)
NEMA Straight Blade
File:CommonNEMAstraightbladeoutlets.png