Wire awg for pulsed current applications

[MarkWilliams]

I'm designing a 120VAC capacitor clearing machine. It uses a transformer connected across a metalized film capacitor via a SSR. It should produce a pulse about 60A rms < 2 sec. I'm looking for a formula to calculate the awg for the wire at 20% duty cycle. Any help would be appreciated.

Thank You
Mark Williams