Nema Starters

Nema size contactors

NEMA electrical motor starters refer to a standardized rating system for the electrical performance of the most common style of American-built motor starters. NEMA starters are rated by size: 00, 0, 1, 2, 3, 4, 5, 6 and 7.

Polyphase Motors

Maximum electrical motor horsepower for different NEMA starters for three phase motors can be found in the table below:

Maximum Horsepower (hp)
NEMA Size NEMA Continuous Amp Rating
(Amp)
Full Voltage Starting Part Winding Starting Wye Delta Starting
200V 230V 460V 575V 200V 230V 460V 575V 200V 230V 460V 575V
00 9 1 1/2 1 1/2 2
0 18 3 3 5
1 27 7.5 7.5 10 10 10 15 10 10 15
2 45 10 15 25 20 25 40 20 25 40
3 90 25 30 50 40 50 75 40 50 75
4 135 40 50 100 75 75 150 60 75 150
5 270 75 100 200 150 150 350 150 150 300
6 540 150 200 400 300 600 300 350 700
7 810 300 600 450 900 500 500 1,000

Ease of selection is a fundamental design advantage of a NEMA-style starter. To select a NEMA starter only horsepower and voltage are needed. NEMA starters have interchangeable heater elements and makes NEMA starters attractive in projects where the motor specification is not known until the start-up date.

Single Phase Motors

Maximum horsepower, full voltage starting, two pole contactors, are indicated below:

Maximum Horsepower (hp)
NEMA Size 115 Volts 230 Volts
00 1/3 1
0 1 2
1 2 3
2 3 7.5
3 7.5 15

Related Topics

  • Electrical - Amps and electrical wiring, AWG - wire gauge, electrical formulas, motors and units

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