Will it work to hook up switches only with white wires?

Question

I'm working on a small cabin. All black wires are run directly to lights. The white wires are run to the switches then lights... so each switch has only white wires.

Would the circuit still work? Why or why not?

It's the exact opposite of the black white being routed to the switch.

ALL lights and switches are wired this way in the cabin. ALL walls are covered so getting to wiring will require ripped out walls.

If it's unsafe, couldn't we just hook up to power in the reverse order (so white is hot)? Would that work? Why or why not?

Answer 1

If the black wire in this situation is the ungrounded (hot) conductor, then it's a possible code violation and unsafe. If the black wire is the grounded (neutral) conductor, then it's a possible code violation but safe.

If the black wire is the ungrounded (hot) conductor, then you're switching the grounded (neutral) conductor. This is a code violation, and is not safe. In this situation, the fixture will always be energized. Touching the wrong part could deliver a fatal shock, despite the position of the switch.

If the white wire is the ungrounded (hot) conductor, then the circuit is wired in a "safe" manner. However, it's a possible code violation, depending on what code you follow. And could be confusing for anybody working on the wiring, which could lead to a potentially dangerous situation.

To determine what's going on, you'll have to take some measurements with a multimeter or voltmeter with the power on. Always use caution when working with wiring, especially live wiring.

• Set the meter to measure voltage.
• Touch one probe to the ground wire or terminal, and the other to an exposed portion of the black wire or a terminal where the black wire terminates.
• Note the reading.
• Touch one probe to the ground wire or terminal, and the other to an exposed portion of the white wire or a terminal where the white wire terminates.
• Note the reading.

If you measured 120 volts (or whatever line voltage is) between the black and ground wires, then the black wire is the ungrounded (hot) conductor. If you measured 120 volts (or whatever line voltage is) between the white wire and ground, then the white wire is the ungrounded (hot) conductor.

Answer 2

This quite unsafe (it's a great way to find yourself doing the 60 cycle shuffle mid-lightbulb-change) situation is a clear NEC 404.2(B) violation:

(B) Grounded Conductors. Switches or circuit breakers shall not disconnect the grounded conductor of a circuit.

(The exception is for dual-pole switches that switch hot and neutral at the same time, so it doesn't apply to your case.)

The "hot on white" case I'd be willing to accept in one or two cases, but for a house to be uniformly wired against Code like this would be rather, well, bizarre. A spot check of wiring to verify that white is indeed neutral (simply measure voltage between the white and bare wires) would be in order, though, yes.

Fixing this requires swapping the black and white wires both at the panel and the lights/outlets.

Answer 3

If you're sure you have no power at the switch, then whomever did the electrical is switching the neutral and that was at one time (a long time ago) okay but not anymore. The switching neutral it is not safe, because even with the light switch off you still have power going to the light fixture and or socket, so when it comes time to change it you will need to find out which breaker it is on and turn it off.

I have ran in to this about 3 times in my career and it only took the first time to know that it was not a safe thing to do. If you're going to leave it this way I would put a label on each switch to remind you of this. The BEST thing to do is to fix it and bring it up to code.