I pull 1,380 watts from my 30 amp line during a 15 minute overlap of 2 grow units, so I decided to go a separate outlet and breaker. Knowing in the future that volume = hydroponics = extra amperage draw (and that my closet could eventually become a room), I thought I should go that route. The second run is a 20 amp breaker, but never exceeds 1,000 amps with all 3 units running (I'm only using 2 now).
Yeah I agree with you, JB42. Being that it happened twice, it's not likely that it's the ballast itself. It seems that the breaker would trip before the ballast were damaged. Maybe the ballast drawing amperage through a lower rated or too long of a cord IS the problem.