Breaker size for 3 phase motors
The breaker size for a 3-phase motor depends on several factors, including:
- Motor power rating: The breaker size is typically determined by the motor's power rating, which is usually expressed in horsepower (hp) or kilowatts (kW).
- Motor voltage: The breaker size also depends on the motor's voltage rating, which is usually 208V, 230V, or 460V.
- Motor current: The breaker size is also influenced by the motor's current rating, which is usually expressed in amperes (A).
- Motor efficiency: The breaker size may also be affected by the motor's efficiency, which can impact the motor's current draw.
Here are some general guidelines for selecting a breaker size for a 3-phase motor:
- For motors up to 5 hp (3.7 kW), a 15-20 amp breaker is typically sufficient.
- For motors between 5-10 hp (3.7-7.4 kW), a 20-30 amp breaker is typically sufficient.
- For motors between 10-20 hp (7.4-14.9 kW), a 30-40 amp breaker is typically sufficient.
- For motors above 20 hp (14.9 kW), a 40-60 amp breaker or larger may be required.
It's important to note that these are general guidelines, and the actual breaker size required may be larger or smaller depending on the specific motor and application.
Here are some examples of breaker sizes for common 3-phase motor applications:
- 5 hp (3.7 kW) motor: 15-20 amp breaker
- 10 hp (7.4 kW) motor: 20-30 amp breaker
- 20 hp (14.9 kW) motor: 30-40 amp breaker
- 30 hp (22.4 kW) motor: 40-50 amp breaker
- 50 hp (37.3 kW) motor: 50-60 amp breaker
It's always a good idea to consult the motor manufacturer's specifications and recommendations for the specific breaker size required for the motor. Additionally, it's recommended to consult with a licensed electrician or electrical engineer to ensure that the breaker size is properly sized for the motor and application.