How do I choose a motor wire size?

Remember the following important principles:

  1. You must size the conductors at 125% of the motor FLC [430.22(A)].
  2. You must size the overloads no more than 115% to 125% of the motor nameplate current rating, depending on the conditions [430.32(A)(1)].

What size wire do I need for a 3 hp motor?





#10 AWG

From Tables 11 & 11A, a 3 hp motor can use up to 300 feet of #10 AWG cable. The application has 160 feet of #10 AWG copper wire installed.

What size wire do I need for a 7.5 hp motor?

Full load amps, wire and conduit sizes for three phase electrical motors.

Power Minimum Wire Size (AWG – Rubber)
(hp) (kW) 230V
7.5 5.6 8
10 7.5 8
15 11 6

What size wire do I need to 100 hp motor?

Full-Load Current and Circuit Protection Data for Three-Phase AC Motors

Motor Horsepower Wire Size
75 230 V 460 V 250kcmil 1
100 230 V 460 V 350kcmil 2/0
125 230 V 460 V 600kcmil 000
150 230 V 460 V 700kcmil 0000

How do I calculate what size wire I need?





How do I calculate wire size for motors?

  1. Multiply the resistivity (Ω•m) of the conductor material by the peak motor current (A), the number 1.25, and the total length of the cable (m).
  2. Divide the result by the voltage drop from the power source to the motor.
  3. Multiply by 1,000,000 to get the result in mm2.

What is the minimum size of cable used for motor circuit?

NEC Code 430.22 (Size of Cable for Single Motor):

Size of Cable for Branch circuit which has Single Motor connection is 125% of Motor Full Load Current Capacity. Example: what is the minimum rating in amperes for Cables supplying 1 No of 5 hp, 415-volt, 3-phase motor at 0.8 Power Factor.

What wire gauge do I need?



To determine what gauge wire you need, consider the carrying capacity and the amount of current the wire needs to conduct (measured in amperage or amps). Wire gauge is directly related to how many amps you need to run through it. The distance you need the wire to go can also impact the gauge of wire you need.

What is the cable size for 7.5 KW motor?

We installed 7.5 Kw Induction Motor. We used 10 mm 4 core cable for it.

What size breaker do I need for a 10 hp motor?

Full Load Current: Three Phase AC Motors

Motor Horsepower Size Breaker
5 230V 460V 15 15
7-1/2 230V 460V 40 30
10 230V 460V 50 30
15 230V 460V 70 40

How many amps does a 7.5 hp motor draw?



AC Motor Full Load Amperes

HP 200 Volts 440-480 Volts
5 17.5 7.6
7.5 25.3 11
10 32.2 14
15 48.3 21

How many amps are in a HP?

AMP DRAW BASED ON HORSEPOWER

HP 1 Phase Amps
115 volt 230 volt
1/2 9.8 4.9
3/4 13.8 6.9
1 16 8

How many HP is 15 amps?

Common Amps to Horsepower Conversions

Amps Horsepower Efficiency
10 A 1.45 HP 90%
15 A 2.17 HP 90%
20 A 2.9 HP 90%
25 A 3.62 HP 90%

How do I convert HP to amps?

Converting horsepower to amps can be done in a few simple steps, or using this simple formula.

  1. Amps = (Horsepower × 746) ÷ Efficiency ÷ Volts.
  2. Watts = Horsepower × 746.
  3. Watts = Watts η
  4. Amps = Watts ÷ Volts.
  5. Amps = HP × 746 V × η × PF.


What is the starting current of 1 hp motor?

5. Motor Starting Current

Supply Size of Motor Max. Starting Current
1 Phase < 1 HP 6 X Motor Full Load Current
1 Phase 1 HP to 10 HP 3 X Motor Full Load Current
3 Phase 10 HP 2 X Motor Full Load Current
3 Phase 10 HP to 15 HP 2 X Motor Full Load Current

How do you calculate motor horsepower?

Use this formula to estimate motor horsepower: Horsepower (hp) = Voltage x Amerage x % EFF x power factor x 1.73/746.

How is horsepower calculated?

The equation to calculate horsepower is simple: Horsepower = Torque x RPM / 5,252. You can use our horsepower calculator below to try it out yourself.

What is HP in electric motor?



Horsepower (hp) is a unit of measurement of power, or the rate at which work is done, usually in reference to the output of engines or motors.

How is electric motor power calculated?

By taking the voltage and multiplying it by the associated current, the power can be determined. A watt (W) is a unit of power defined as one Joule per second. For a DC source the calculation is simply the voltage times the current: W = V x A.