Your basic bathroom light over the mirror fixture. The house was built in 1957 with two wire circuits.
Two cables come into the box. The white neutral wires are connected together and are connected to nothing else. The black wires feed the light fixture. There is 120v between them.
This isn’t normal, is it?
What isn’t normal?
Also, 120v between what and what?
There should be 120v between each white and black wire. I would think that there would be 0v or 120v between two black wires.
Is the light on a wall switch (as opposed to a switch integrated into the fixture).
I’m guessing it’s either some wonky switch wiring or the power then goes onto feed something else (in series(?)).
If it were my house, I’d pop the fixture out, figure out which wires are the source, figure out where the other wires go and either fix it or decide that it was, in fact, correct, and put it back together.
If there’s a wall switch, open that up. You might find that extra pair of wires in there.
120v between the two black wires, on an otherwise working circuit, tells me the ‘other’ black wire eventually finds it’s way back to ground.
If the wires don’t (and never did) power something else, I have a funny feeling the black wire is a switch loop and the white wire is just along for the ride (which, IIRC, is required by code, but I don’t think it would have been back then).
It may be.
Does the black (hot) wire come in to the fixture and connect to one terminal/screw? Then is a black wire connected to the other terminal/screw and run to the light switch? If so, then the white wire coming back from the light switch would be connected only to the white wire in the fixture.
This was very common some years ago. The two-conductor sheathed cable electricians used would have a black conductor and a white conductor. They would just use this same cable to wire down to the light switch. Of course, modern electricians would use a different set of colors (though white would still be neutral) for the hot conductor down to the switch and back to the fixture.
I’m settled on it just being a switch loop. Anything else and it would mean the OP has things wired in series, which would (almost certainly) be incorrect in this situation.
But, again, there’s always the chance that things are simply wired in incorrectly, but in a way that still allows the fixture to work.
Thanks, Zonex, that’s it, only one cable in the switch box, both wires connected to the switch. I’ve never seen it done that way, but I’ve not worked on much sixty five year old wiring.
Yes, sounds like it’s wired fixture first:
----b----------(light) --------b-----
----w----------- x ----------w------: switch
instead of switch first in the circuit, which I would consider more normal - in which case reverse the position of switch and light in above diagram.
The problem is, remove the switch the power is still live, whereas the other way (proper?) everything downstream of the switch is dead when t’s off or removed. At least they kept the colours correct.
IANAE but I don’t think it’s normal to use the switch to open the neutral (white) wire.
In “weird” situations like this, I like to disconnect everything and determine what all the wires are connected to using a DMM.
The neutral are not switched, although both colors in a cable are connected to the switch.
What I’m guessing is:
The live (black) goes directly to the fixture and then on too the switch where it connects live (black) with neutral (white).
So even when the switch is OFF the fixture is still at 120V, just the circuit is open (no connection to neutral) so it won’t light up. The neutral runs unconnected straight through the light fixture to the switch.
that would work but is not healthy. I assume the light and switch are at the end of the run.
I wish I had some graphics.
The fixture is connected to the circuit breaker. A cable runs from the fixture to the switch, carrying 110v and the fixture hot lead. The switch is connected only to the fixture box. As MD-2000 said, the fixture box is hot regardless of the position of the switch. A very bad way to wire it, but apparently common in the 1950s.
MS-2000’s schematic is correct.
Oh, yeah, the fixture box is three inches from the wall, screws won’t reach the box. The switch box is fastened to the stud with a bent nail. Jesus.