Restaurant Equipment Buyers Guide : plugs
Typically, an electric utilitys distribution system begins at the substation, where three-phase lines with three separate lines branch out. The conductors on a three-phase power line are referred to as phases because each of the three carries electricity at a slightly different wave form or phase.
On a single phase service, there are two incoming 120 volt lines. On a three phase service, there are three.
There is a limit to the number and size of electric loads that a single-phase power line can supply. The need for three-phase service usually occurs where large motors are present. Up to a motor size of about 5 horsepower (hp), single-phase service is usually adequate. Beyond 5 hp, the single-phase line may have trouble delivering the current needed to start the motor. Starting a motor can require six times as much current as it takes after its running.
On a single phase service, there are two incoming 120 volt lines. On a three phase service, there are three.
There is a limit to the number and size of electric loads that a single-phase power line can supply. The need for three-phase service usually occurs where large motors are present. Up to a motor size of about 5 horsepower (hp), single-phase service is usually adequate. Beyond 5 hp, the single-phase line may have trouble delivering the current needed to start the motor. Starting a motor can require six times as much current as it takes after its running.
Plug Types
| 2-Pole, 2-Wire | |||||
| 15 Amp | 20 Amp | 30 Amp | 50 Amp | 60 Amp | |
| 125 Volt |  NEMA 1-15 | - | - | - | - |
| 250 Volt | - |  NEMA 2-20 |  NEMA 2-30 | - | - |
| 2-Pole, 3-Wire Grounding | |||||
| 15 Amp | 20 Amp | 30 Amp | 50 Amp | 60 Amp | |
| 125 Volt |  NEMA 5-15 |  NEMA 5-20  NEMA 5-20 T-Slot (1) |  NEMA 5-30 |  NEMA 5-50 | - |
| 250 Volt |  NEMA 6-15 |  NEMA 6-20  NEMA 6-20 T-Slot (2) |  NEMA 6-30 |  NEMA 6-50 | - |
| 277 Volt AC |  NEMA 7-15 |  NEMA 7-20 |  NEMA 7-30 |  NEMA 7-50 | - |
| 347 Volt AC |  NEMA 24-15 |  NEMA 24-20 |  NEMA 24-30 |  NEMA 24-50 | - |
| 3-Pole, 3-Wire | |||||
| 15 Amp | 20 Amp | 30 Amp | 50 Amp | 60 Amp | |
| 125/250 Volt | - |  NEMA 10-20 |  NEMA 10-30 |  NEMA 10-50 | - |
| 3Ø 250 Volt |  NEMA 11-15 |  NEMA 11-20 |  NEMA 11-30 |  NEMA 11-50 | - |
| 3-Pole, 4-Wire Grounding | |||||
| 15 Amp | 20 Amp | 30 Amp | 50 Amp | 60 Amp | |
| 125/250 Volt |  NEMA 14-15 |  NEMA 14-20 |  NEMA 14-30 |  NEMA 14-50 |  NEMA 14-60 |
| 3Ø 250 Volt |  NEMA 15-15 |  NEMA 15-20 |  NEMA 15-30 |  NEMA 15-50 |  NEMA 15-60 |
| 4-Pole, 4-Wire | |||||
| 15 Amp | 20 Amp | 30 Amp | 50 Amp | 60 Amp | |
| 3Ø Y 120/208 Volt |  NEMA 18-15 |  NEMA 18-20 |  NEMA 18-30 |  NEMA 18-50 |  NEMA 18-60 |
