Q: The Volts field in the Transfer Switch dialog box only lists voltages with 1, 2, or 3 poles. How do I model a 4-pole transfer switch?
A: Select the appropriate voltage in a 3-pole configuration (3P 4W). Use the Notes Settings dialog box and the Insert and Modify Labels command to add notes to schedules and the one-line diagram that the transfer switch is a 4-pole transfer switch.
There are internal differences between 3-pole and 4-pole transfer switches, and each has different ground-fault considerations for the upstream devices. When transfer switches are being bought, and the system is being constructed, these differences do matter.
However, the number of wires and overall configuration of the feeders would be functionally identical in either case. Design Master’s wire and breaker sizing calculations would not change. Calculations for short-circuit fault, voltage drop, and arc-flash would also be unaffected. Therefore, modeling a 4-pole transfer switch as a 3-pole would not make any difference when creating your electrical distribution in Design Master Electrical.