First, switch wiring. Normally when you wire a light switch, you have your 14-2 (or 12-2, or whatever, I’ll use 14-2 but the gauge isn’t really relevant) coming into the box, then another 14-2 wire leaving the box, and the two black (hot) wires are connected to the switch. A sequential setup, if you will: Power, switch, light. A simple diagram.
However, in certain situations, it’s more convenient to run only one 14-2 to the box. For example, you might do this if you have a supply of constant power at the light fixture, but no source of constant power near the light switch. So, you bring the supply 14-2 into the box, and then use a single 14-2 to run to the switch. The black wire is connected to the supply at the light and one terminal of the switch, and then you connect white to the other terminal of the switch, and back to the light in the first box. You are supposed to mark the white on both ends to indicate it is being used as hot rather than neutral. Here’s a diagram of the setup.
I think of it as a giant T - supply power comes in the top left, light is on the top right, and the vertical line is the wire to the switch that carries supply hot and switched hot on the “wrong” wire. It’s useful when there’s no power source near the switch, but there is power at the light fixture it controls.
Note that in the box at the light, you’d have three 14-2 wires coming in (6 conductors plus 3 grounds) - supply, power for the light, and the run for the switch.
Okay. It’s like the previous owner of our house learned this trick…and wanted to use it everywhere.
So, there’s a box in the shed that has:
A constant supply coming in.
A constant supply going out to outlets in the shed. (No GFCI, but we’ll ignore that issue for this discussion.)
TWO of these fucking T setups. One controls a light in the next shed, and one controls a light in the shed this box is in. Each one of these generates TWO sets of wires (supply is already accounted for in the first bullet).
So, I have 6 sets of wires coming into this box (hot, neutrals, and grounds). Oh and on at least one of them, he switched the neutrals, not the hots, so there are white wires serving as hot (unmarked, naturally) and who knows what else is going on. At the very least it’s a violation of the code for the amount of conductors in that size of box.
The worst part, though: It wasn’t necessary.
Both light switches are near outlets that have constant power that could easily supply the switches.
The light in the second shed could run directly to the switch that controls it, and that would have saved wire and complexity, and make diagnosing an issue much easier. There’s no reason to run that complex circuit.
The lights in the first shed, where the box is, are somewhat near the box, but not so close that the complexity of this setup is worth it.
Even if he did want to supply the switches directly from that box for some reason, he could still cut it down to FOUR sets of wires in the box, with no unusual usage of wires and a much more understandable setup.
It’s insane. I’m going to redo it soon, and I don’t think I’ll need to buy ANY supplies to do that. In fact I bet I’ll have extra wire when I’m done (I may need smaller wire nuts, which I have already).