A furnace blower motor rated at 115 VAC has what allowable voltage variance?

The allowable voltage variance for a furnace blower motor rated at 115 VAC is ±5 volts. This means the motor can safely operate within a voltage range of 110 to 120 volts. Maintaining such voltage tolerances is essential for the efficient operation of the motor, ensuring it does not overheat or experience performance issues due to under or over-voltage conditions.

Staying within this variance helps to protect the motor's components and prolong its lifespan. Allowing for a ±10 volt variance could lead to excessive voltage levels, risking damage to the motor or failure of the unit, which is why stricter limits are usually applied in practical applications to ensure safe and reliable operation.