jar546
Forum Coordinator
Electrical equipment is generally specified in terms of volt-ampere (VA) or wattage for their input requirements. Motors, however, deviate from this norm by being rated primarily in terms of their horsepower output. A horsepower is approximately equivalent to 746 watts. The circuitry that supplies power to these motors is designed based on the motor's current input, rather than its horsepower or watt output.
Factors like motor inefficiencies and power factor also influence the input current to the motor, although these variables are not usually indicated on the motor's nameplate. For accurate input ampere specifications, industry professionals can refer to Part XIV of Article 430, which contains tables that align with accepted industry standards.
In instances where motors are rated in watts instead of horsepower, it's crucial to continue sizing the circuit according to the motor's input current in amperes. Relying solely on the kilowatt output for this purpose can result in both improperly sized conductors and inappropriate overcurrent protective devices, thereby compromising the motor and circuit components' safety and functionality.
Factors like motor inefficiencies and power factor also influence the input current to the motor, although these variables are not usually indicated on the motor's nameplate. For accurate input ampere specifications, industry professionals can refer to Part XIV of Article 430, which contains tables that align with accepted industry standards.
In instances where motors are rated in watts instead of horsepower, it's crucial to continue sizing the circuit according to the motor's input current in amperes. Relying solely on the kilowatt output for this purpose can result in both improperly sized conductors and inappropriate overcurrent protective devices, thereby compromising the motor and circuit components' safety and functionality.