Energy Withstand

For Project calculations, PowerPac will size the cable to meet short circuit performance requirements as specified in AS3008.1.x. (I²t <= K²S²). If these details are not entered, PowerPac will use the default trip time (1 second at the MSB, 0.1 seconds for all sub-boards and circuits) and the Prospective Short Circuit Current at the point of connection for that cable.

The preferred method to resolve this is to either enter the Short Circuit Trip Time and multiplier/current at the upstream short circuit current. These values are not dictated within AS3008.1.x and may differ between device manufacturers and device families. These details can be obtained from a Time/Current or Let Through Energy curve for the selected protective device.

The other method is to tell PowerPac to ignore the short circuit performance requirement. Cables will still be sized to meet load and voltage drop requirements but PowerPac will assume that in the event of a fault, the selected protective device will protect the cable.

The reason that the active conductor is showing in red is because you have locked the size and number of parallel conductors per phase and the resultant conductor surface area does not meet the let through energy vs cable withstand energy requirement

To change this setting, please open or start a new calculation and select File | Properties from the main menu. Change the Shot Circuit Performance setting to be either ‘Only when device I²t is available ‘ or ‘Never Calculate’. PowerPac will still size the conductors to meet load and maximum allowed voltage drop requirements but will not check that the circuit breaker will protect the cable in the event of a bolted fault or short circuit.