Function of an Electrical Junction Box?

What exactly does running your electrical wires through a junction box do? Does it alter the voltage or amperage? Recently a ''licensed'' electrician replaced the meter base in my home (older home), and moved the panel box (which means that he disconnected all the wires coming into the panel. Then without warning me, he reconnected the wires, and turned on the breaker.

This blew through 2 ''surge protectors'' and destroyed my computer (flash of lights, spark, pop, then smoke and the lasting smell of burnt miscellany for an hour later).
He claims that this occurred because the wires were going through the old fuse box, as he had not as yet sorted them and rerouted them.

Since the stove, furnace, and a few other things were not ''going through'' the old fuse box, I suggested to him to connect those so that I have power for the night. He did, everything went well until he connected the stove. It did the same thing as the the computer - it blew out the mother board (he plugged it in, then threw on the breaker).

He now claims that the damage is due to the fact that I had him connect the wires without going through the junction box (even though he connected the first one that blew out the computer before I even got involved in the decision making process).

I am unclear how a junction box could have made any difference to the fact that the wires were obviously not properly connected at the source, and that as a qualifed electrician, he would need to be coached to unplug all appliances before reconnecting power to a home (especially one that is still on knob and tube in some areas)

By Enna