So my wonderful hubby replaced our unsafe Federal Pacific panel, circa 1958, with something that isn't just waiting to go up in smoke. The house was part of a chicken farm, so there is an outside panel that cuts power to this panel in the basement - so we were sure nothing was hot. He has an extension cord with clips on one end that he connected outside at the hot panel so he didn't have to use a flashlight. Then basically labelled the wires and swapped to the new panel. Easier said than done - extra wires jammed in everywhere including the main. The ouside panel has 200 amps divided into 100 for our house and 100 for a barn that was torn down, so we need to run a new wire to get 200 to the panel, so still 100 at this point. He does HVAC by trade.