spark chaser needed

The problem with tapping into top or bottom and setting up a dedicated line to ny building is, the current box does not have ANY room for expansion. No matter what, i have to replace the panel box and was thinkn the same bout havin the pwr comp disconnect the meter for a lil bit but i think i can b-cap the main in and slide the old box out n new box in while its still hot. Iv wired stuff hot b4, but nothing over 110, which will grab u n hold on, where more often than not, 220 will knock u off. In high school, we used to take the work lead in 1 hand and the ground in the other and turn the welding machine on n crank up the amps n bet on who would let go first. Not the smartest thing to play with electricity, but it supplemented my fuel n nicotine habbit.