Home Wiring (please don't kill me)
April 27, 2015 9:45 PM   Subscribe

Hanging a new pendant light fixture, simple, but can you help explain this wiring?

This fixture came with the worst instructions imaginable, just arrows pointing at bits of the lamp. Gah!

The lamp has 4 wires. Three are bundled together, one of which has a green stripe, the others are in clear tubing not colored or marked. The fourth wire, solid green, is attached to the fixture via a screw (that one I'm guessing is the ground wire to screw into the junction box.

My junction box has two wires, white and black.

Which wires from the lamp go to which in the box?

(yep I've switched off the mains to the room)
posted by artdrectr to Home & Garden (5 answers total) 1 user marked this as a favorite
Post pics please.
posted by ryanrs at 9:51 PM on April 27, 2015

None of that sounds normal or good to me. I've hung plenty of fixtures.

Try the manufacturerer's website or their helpline. Otherwise, return the item.

If you got it on discount and can not return it, that would explain a lot. You could always cap off the unimportant wires with electrical tape AND plastic electrical caps, but I wouldn't bother with the risk or hassle.
posted by jbenben at 11:29 PM on April 27, 2015

Without pictures, it is a bit difficult to be certain.

Does the green stripe wire get bundled with the others in clear tubing all the way to the lamp socket? If so, it is likely to be a ground for the socket itself, and is probably just clear-ish plastic for aesthetic reasons. If so, it needs to be treated as a ground.

You can use a continuity meter to determine the correct wiring for the two "clear" wires. One is the hot. If you look in the base of your lamp socket, you will see a center contact in the middle at the bottom. That is the socket's hot contact. When you identify which of the two clear wires it is, blacken the corresponding lead with a Sharpie. The ring of the lamp socket, the screw-in portion, is neutral, and you should validate that with your continuity meter as well. Do not color that wire.

The hot/black connects to the junction box black. The neutral/clear connects to the junction box white.

Now, we can discuss stuff regarding the ground. Look at the lamp socket itself. Usually a socket dangling on the end of a long cable (sometimes in a metal tube) for a pendant. A metal tube would typically provide grounding between the socket and the cap over the junction box, but if it is just cable, a ground is reasonable. Imagining the socket with a bulb inserted, is some exposed part of the body metal? You can see if you can use a continuity meter to establish whether that green striped wire is ground for it.

Is the green wire attached to a mounting bracket for a round box?

Round box (what you'd typically be trying to mount a lamp to):


Example of a mounting bracket:


The metal strap across the box that's screwed to the box. Yours may be very different, even a round plate, but in any case will have screwholes for attachment to the round box. I've seen ground wires come screwed to this strap. It is not meant to stay screwed to the strap. The manufacturer wants you to look in the box and see if you can screw it to a ground point in the box (usually just one). You can leave it attached to the strap if no alternative grounding point is available, though.

Most modern residential inside wiring is done with Romex these days. So whatever ends up happening, make sure that all your grounds are electrically attached to the ground on the Romex.

The really important bit in all of this is that you need to be safe, so if you don't understand something, ask. Pictures would be helpful as well.
posted by jgreco at 2:37 AM on April 28, 2015 [3 favorites]

Response by poster: I gotta apologize that I didn't include to say this is a two bulb/socket lamp, and that taking pics was not possible yesterday.

jgreco: Thanks, very helpful. I think 2-socket clears up why there are 2 hot leads, and a green striped ground bundled together. I didn't understand why the solid green wire was also necessary, or how they all attached.

Here is a pic of the lamp and of the box.
posted by artdrectr at 10:31 AM on April 28, 2015

Well, I'd guess the lamp wiring goes like this:
solid green/yellow stripe connects to the metal frame of the fixture
clear/green strip connects to the threaded shell contact of both sockets
clear/no stripe connects to the center contact of the sockets, separate wire for each one

I would recommend verifying this with a continuity meter before proceeding.

As to the connections, if the fixture wires are as I described above, the green/yellow stripe gets fastened to metal junction box*. The clear/green stripe connects to the white wire. And both clear wires connect to the black wire.

* This assumes the metal junction box is in fact connected to earth. If there is a bare copper wire screwed to the box somewhere, that is good. If the box is not grounded, then that is bad. In that case I would maybe leave the green/yellow stripe wire disconnected, but I'm sure that's not the right way to do it.
posted by ryanrs at 11:26 AM on April 28, 2015

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