Convert a light fixture into a junction box?

[stioc]

Is there a way to convert a light fixture into a surface mounted junction box? If so I'd like to run PVC conduit from the junction box (previously light fixture) to the ceiling and hook up 3 flourescent lights. The advantage is that I won't have to run a new circuit and the on/off switch is already in the right spot which will save me a lot of time and effort ripping into the drywall.

Also, is it OK to run ROMEX inside a PVC conduit? I know the best way will be to use individual wires and use a metal conduit but I'm looking for the easiest way out.

 

[nissan_crawler]

No, there's no way a fixture can be used as a junction box.

Yes, romex can be ran in pvc. There is a wire fill calculation that should be done when running wires in conduit, however, it won't be an issue for a few lights.

 

[stioc]

Aww bummer! So there's no way to replace a light fixture with a surface mounted junction box either? one that can utilize the wires that were used to power the light fixture?

How can I tap into that circuit easily and extend the wires to the ceiling (the fixture's on the front wall of the garage and I want the fluorescent lights on the ceiling.

 

[Charles (in GA)]

You cannot use the fixture itself as a raceway for other circuits or junctions for other circuits. You could easily add a junction box at this point however.

If all you are trying to do is pick off the existing lighting circuit and run to another fixture, that is OK so long as you don't over fill the boxes or conduits. Most likely there is a box in the wall behind the wall mounted light fixture you want to tap off of.

Chapter 9, note 9 of the NEC says that you treat a multi-conductor cable in conduit as a single conductor for FILL purposes, and use the major diameter of the ellipse of the romex as the diameter of a circle to calculate the area of the cable and percent of fill. One conductor for fill purposes can go to 53% of the conduit inside area.

Complicated way of saying the Romex is most likely OK in the PVC conduit you are using.

Charles

 

[nissan_crawler]

Ok...maybe we're talking two different things here. A light fixture is what your bulbs go in. Are you talking about the electrical box the fixture mounts too?

If so, you can remove that, and if you can get a plate that fits (doubtful, I think), use it as a junction box, or if not, just install a normal junction box in it's place.

 

[nissan_crawler]

Ok, Charles and I are thinking two different things here, and either of us might be right.

Are you hooking wires to an existing light on an existing box? If so, he's right, you can just wire it up without the junction box.

I was under the assumption that the light fixture itself is gone, and you're dealing with an open box at the moment.

 

[ddawg16]

Hold on regarding that light fixture....

If I understand correctly what you want to do.....you have a light fixture....that I'm assuming is on the wall? Say a foot from the ceiling? Or is it already in the ceiling?

In any case, you want to take the light fixture off and just re-rout the wires to a different light?

If so...then I think it will work....

The typical light fixture is actually connected to your typical round box. Remove the light fixture and now you have a round box in the wall/ceiling. They make plates for those so that part is not an issue.

About the only issue (and it's not really an issue) is how its wired. Depending on the age and where you are, it can be wired in one of two ways. It has both a hot and common going to it...light connects to the hot, and two wires go down to the light switch....one is connected to the common and the other is the return from the switch which in turn connects to the common of the light.

The other method is the common goes directly to the fixture and the common comes from the switch. The downside to this wiring is that if you want to install a ceiling fan, it has no power unless the light switch is on...where as the first method gives you power all the time if you want it.

In any case, just take those two wires....wire nut your romex to them and run that to the new light(s). They will work just like the previous light did.

Did you get all that?

 

[logical]

Do you have access to an attic above? If so, you should put the junction box up there and properly run more romex and install more fixture boxes in the ceiling (retaining the existing one if you want). Much, much cleaner install.

If surface mount is your only option, simply remove the fixture and mount an open-back junction box right to the existing fixture box and go from there.

 

[Kevin54]

I think what he has is already a junction box but has a light fixture mounted to it. The type of light fixture he has, has the metal mounting bar that goes corner to corner of the box, then the light fastens to it. Same way my garage is. The box is mounted 1/2 or 5/8" below the rafter and then drywalled around it. It can be used as a junction box or for a light fixture. But to run conduit off of it, you will need to get the proper extension for the box, space it down, put a plate over the top, then run the conduit out of the side.

 

[stioc]

Yes Kevin54 and ddawg have the correct picture of what I'm dealing with. The tricky part is, finding a "surface mount" junction box that will screw into the existing box (that the light fixture is attached to). In other words this new junction box will have to allow for external conduits as well as be open in the back so I can connect it to the existing wires.

 

[logical]

Yes Kevin54 and ddawg have the correct picture of what I'm dealing with. The tricky part is, finding a "surface mount" junction box that will screw into the existing box (that the light fixture is attached to). In other words this new junction box will have to allow for external conduits as well as be open in the back so I can connect it to the existing wires.

You should have no problem finding that kind of box. I've used dozens of them. And really, you just need one with a knock-out plug in the back...you are just pulling one wire thru it. As I posted way up higher on the page, it's actually called a box "extension".

 

[stioc]

Awesome, thanks!