How to Select Circuit Breaker, Conductors, and Conduit for a Three-Phase 200 Volt Heater

What steps are involved in selecting the appropriate circuit breaker, conductors, and conduit for a three-phase 200 volt heater rated at 9,600 watts?

To determine the correct setup for the electrical system needed for a three-phase heating circuit, calculate the necessary current, select a circuit breaker with a higher current rating, and calculate the conductor size based on 125% of the circuit breaker's current. Lastly, select conduit size based on the type, number, and gauge of conductors.

Explanation:

To select the appropriate circuit breaker, conductor, and conduit for a three-phase (3∅), 200 volt heater rated at 9,600 watts, we must first calculate the current. The formula to find the current (I) in amperes (A) in a 3-phase system is I=P/(√3*V*PF), where P=Watts, V=Voltage, and PF=power factor.

In a heating circuit, the power factor is usually 1, so I=P/√3*V. Substituting, we get I=9600 / √3*200, which is ~27.71A. So, the circuit breaker should be the next size larger than 27.71A.

Conductors must be rated for at least 125% of the circuit breaker current rating. This ensures that the conductors can handle the current without overheating or becoming a safety hazard.

Finally, the protective conduit sizing would depend on the type of conduit, the number of conductors, and the gauge of the conductors used. The conduit should be able to accommodate the conductors while providing adequate protection.