I have an existing residential 200A. main lug panel already feeding some subpanels with a 100A. DP ckt. bkr, a 30A. Dp ckt. bkr, and some other DP utilization ckts. feeding electric ranges, etc. I'd like to add some more ckts. for an addition on the home and there are several remaining unused spaces on this panel. My question is, how do I determine the maximum amount of ckts and ampacity still available without overloading this panel, per the NEC? Or, should I take readings to determine the peak usage and base the available leftover on those?
Thanks,
Andy
