Why did my 100A panel trip with only 8 * 15a circuits then? 4 were on left leg and 4 on right leg. Draw was around 50A on each side, more like 45/55A measured with clamp. However this is the bit i wasn't certain about. You seem to be saying i could have used 160A @ 120V on a 100A panel as long as i balanced each side properly?
How hot was it at the panel?
Breakers DO derate with temperature.
I've seen a LOT of cases of a breaker tripping when it's at 60% or less of it's rated capacity, when the area the panel was in was hot and the panel wasn't well ventilated.
Could also have been an old breaker that was wearing out - breakers last a long time but NOT forever.
Was the main breaker ITSELF a 100 amp unit? Some panels don't have the main breaker in the panel, they feed from somewhere else and the breaker for the circuit FEEDING the panel may have had less than a 100 amp breaker on it.
This is fairly widespread in apartment setups, one main panel with a bunch of 50 amp 234 VAC breakers feeding secondary panels in each apartment with no "main breaker" on the secondary panel.
Just because the PANEL itself is rated 100 amps doesn't mean the feed to it is always 100 amps (and in practice, most panels aren't rated 100 amps anyway, 125 amp rated panel is the norm in "100 amp feed" setups).
And yes, if everything is installed correctly, NOT overheating, NOT wearing out, and balanced well you can draw 160 amps at 117 VAC continuous from a 100 amp 234 VAC panel while staying within NEC limits - realistically you probably won't manage to balance PERFECTLY but miners aren't hard to keep balanced, it's the other stuff in the place that will commonly cause an imbalance.