First of all, i would like to say I love the show. I have learned alot of useful information from the specialists on the show.
I Just finished running wire for a customer from one shed to another. The Original shed has a 2-Fuse box with a disconnect handle. (Sorry I usually recommend that all fuse boxes be removed and replaced with a circuit breaker box, NEC will require this within the next 2 years)
The fuse box had both fuses installed; but only the left side was hot. I ran jumper wires to make the right side hot; once the power was turned back on the fuses blew. Come to find out, when the shed was initially wired it was run with 12-2NMC on a 110VAC Circuit. The wiring ras then upgraded from the breaker box in the house to the fuse box in the shed, to a 4-wire 220VAC circuit.
Now there was 220VAC into the shed which was split so that each side of the fuse block was 110VAC. Now there was 110VAC into each side, 110VAC out the left and 3.8VAC out the right. The fuse was good but would not allow voltage to pass through the right side. (Again I hate fuse boxes and normally only remove them to upgrade to breakers.) I managed to get voltage through the right side.
Now I have 110VAC going to the new shed. But when the light switch is turned on, it fries the switch. Wiring comes into the shed into a box. It is then pigtailed to the run for 3 outlets and 2 flourescent lights.