Wiring a light fixture

[Ralph Wiggum]

I have a fixture in the basement that I keep bumping with my head, so I bought a low-profile light to replace it figuring it would be an easy swap. Well, I pulled the old one off and I have no clue what's going on up there. Does anyone recognize this? My new light has a white, black, and green wire to hook up.

As you can see, the black wires from the ceiling are not hooked up to anything, and the white and yellow wires are hooked up to terminals on the fixture.

There is only one switch to control this light, if that matters, and it is the only light on the circuit for that switch.

Help!!!

[mntraveler]

I'm far from an electrician, but I would try hooking the white on the old fixture to white on the new one. Then I'd assume the yellow on the old fixture is hot so I'd connect that to the black. I don't see a ground in your photo (either your house must be a few years old or you bought it from a DIY I'd guess) so I think you could hook it to the white, or just leave it.

[Ralph Wiggum]

No ground--the house was built in 1964.

[Whoaru99]

Huh? Strange-looking connections in there.

Looks like a DIY install. Yellow seems like a strange color to use for a hot wire (too close to green for my taste), and that white wire connection looks odd. Generally, IMO, those white wires would be pigtailed and then connected to the fixture.

DON'T connect the green wire to the white whire. Attach it to the metal box or leave it disconnected if there is no grounding wire.

I'd be tempted to investigate that whole circuit more just to see how that yellow wire comes into play.

Evidently it's some type of conduit wiring? I can't quite see into the box where the cables come in.

[Ralph Wiggum]

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Evidently it's some type of conduit wiring? I can't quite see into the box where the cables come in.

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Metal conduit.

[sparcebag]

Wiggum the yellow & white come from the switch,the black (Hot) & white (Neutral) are main wireing.put your new white in twist nut whites,put your black on the yellow,Older style wiring.

[Whoaru99]

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Evidently it's some type of conduit wiring? I can't quite see into the box where the cables come in.

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Metal conduit.

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In that case, definitely connect the green wire to the metal box.

[Ralph Wiggum]

Thanks guys! Looks like another problem solved by FM

[TNFL]

Did you take the switch off the wall just to check the wiring? Sometimes the black could be used to hook up a ceiling fan. If you wanted more info????

[JohnMickish]

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Wiggum the yellow & white come from the switch,the black (Hot) & white (Neutral) are main wireing.put your new white in twist nut whites,put your black on the yellow,Older style wiring.

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This is exactly what is going on here. The home run was brought to the light box instead of the switch box. It's a very common thing to do, especially when working with conduit since you are not limited to two or three wires and colors like you are with Romex, you can wire more efficiently and use less copper. Your switch box is getting it's power from another location. The yellow wire is called a switchleg, and most electricians use a different color wire for switchlegs and travelers to reduce confusion.

This is more than likely not a homeowner job as it looks neet and clean. Yes, ground the green wire to the box, and the reason you don't see a ground is either because they are using the conduit as the ground (legal as long as it's not flex, or greenfield) or back in those days they didn't ground light fixtures. Either way you are better off attaching it to the box.

For everybodies information, nowhere in the codebook does it say that you have to use black as your hot wire. The only colors specified are green (ground) white or gray (neutral or grounded conductor) and orange (high leg on a 480V Delta system). It is common practice to use black/red/blue/white on 120-208V systems and brown/orange/yellow/gray on 277-480V systems but it's not written in stone.

Now to confuse everyone you can legally run a two wire romex to a light box, drop the white (neutral) wire off, tie the black to the white wire (properly reidentified) going to the switch and run the black wire back to the light box as a switch leg. There you have a properly reidentified hot white wire.

[Ralph Wiggum]

Thanks to all for the help! I can walk downstairs without ducking now