If a motor is connected to a 230-volt circuit, how does the branch circuit current compare to a 115-volt circuit?

When comparing branch circuit current drawn by a motor from a 230-volt circuit to that of a 115-volt circuit, it's essential to consider Ohm's Law and the relationship between voltage, current, and power in an electrical system.

In a resistive load, power (measured in watts) is calculated by the formula:

Power (P) = Voltage (V) x Current (I).

For the same motor, if it operates at the same power level on both voltage supplies, the power must remain constant. When the voltage is doubled from 115 volts to 230 volts, the current required to maintain the same power output must be halved, as described by the rearranged formula:

Current (I) = Power (P) / Voltage (V).

Thus, if the voltage is increased to 230 volts, the branch circuit current will indeed be half of what it would be at 115 volts for the same power output. This illustrates the inverse relationship between current and voltage when maintaining a constant power level in a circuit. Therefore, the branch circuit current on the 230-volt circuit will be half that on the 115-volt circuit.