Someone, somewhere thought this junction box was a good idea.
I had to totally disassemble it when we demoed the laundry room and one of my goals with re-wiring the basement is to completely remove all it's nastiness. The plan is to remove one circuit at a time until there's nothing left in this rat's nest.
The first circuit I removed was the one that goes to our refrigerator. The original circuit went from the main panel, to this junction box, then lopped around the basement only to come up through the floor right above the main panel (why loop all around the basement???). Once on the main level, the circuit ended in a non-grounded receptacle. An extension cord plugged into the receptacle ran through hole in the wall, through the inside of a cabinet, and eventually reached the fridge. Every once in a while the fridge plug got bumped and the fridge turned off until we noticed it. This had to change!
I removed the old circuit and it's crazy loop through the basement and ran a new, grounded, circuit straight from the main panel to a new receptacle on wall behind the fridge. It was perfect!
The next day I went down to work on the basement and turned on the radio on my old boom box. To my surprise, the boom box was dead. I tried everything but it was just plain dead. As I traced the circuit back to see what was going on, I ended up in that horrible junction box and things were going haywire in there! Wires that shouldn't have current had current, turning off certain circuits didn't cut power to the circuits, and things were just generally out of whack. I turned off power to all the circuits in that junction box and started sorting things out. Let me try to explain what was going on with some pictures.
This is what 3 simple circuits look like. Power runs down the black wire, goes to something that needs power (like a light bulb) and returns down the white wire. I added a junction box to the picture but for this illustration, each wire just connects to a new wire and continues on from the junction box.
In reality, it's never this cut and dry. It's common to connect all the white neutral wires in a junction box but each circuit still has a black (hot) wire and a white (neutral) wire.
Now what made ours weird is that each circuit didn't have it's own neutral wire going from the junction box back to the main panel. It only had one wire that was carrying power from all the circuits back to the main panel. While this technically works, it's not the way to do it. Booo.
Imagine the middle circuit is our refrigerator circuit. When I removed the old circuit, I took out the black and white wire from the main panel to the junction box and the black and white wire from the junction box to the fridge.
Ours was much messier and there were more than two circuits, but this is essentially what we were left with. See a problem here? Neither circuit has a white (neutral) wire that goes back to the main panel. Usually if a circuit has a black (hot) wire but no white (neutral) wire to go back to the main panel, the circuit just doesn't work and it doesn't really cause any problems other than nothing turns on. In our case the neutral current still found a way back to the main panel. The current on the top circuit traveled down the black wire into the light bulb, then continued on to the white wire into the junction box. From there it continued on the other white wire, into the bottom light bulb, and back down the bottom black wire (going the wrong way) back to the main panel. The bottom circuit did the same thing in reverse.
This essentially created a 240 volt circuit instead of two 120 volt circuits. Sometimes things are wired like this on purpose because appliances like electric heaters sometimes need 240V. In our case, this wasn't the intended outcome and any appliances on any of the combined circuits that that couldn't handle 240V got fried. Specifically my radio, our drier, and both garage door openers.
I guess I learned an important lesson: Never assume anything was done correctly in an old house. If you change something, make sure anything that can be affected is done right after the change. And make sure you have an emergency fund. Because mistakes are rarely inexpensive!