Steve Nosko wrote:
"Power is calculated from "RMS" values of voltage and current."

Steve is correct! I apologize.

If you have a square wave of minimum peak to peak value of zero volts,
its maximum peak to peak value must be 1.414 x the d-c value. Then,
1.414 Vd-c x 1.414 Id-c = 2 Pd-c.

2 Pd-c x 1/2 t = Pd-c for an average.

Best regards, Richard Harrison, KB5WZI