ceiling boxes and electrical safety (replacing a "halo" can with 4" round box)

[RustyShackleford]

I am replacing a 6" Halo recessed "can" light with an ordinary surface-mount light designed to mount on a 4" round box.

The half-assed thing would be simply to put in a 4" round box with the adjustable struts designed to position it between to ceiling joists; but that would leave a gaping hole, bad for weather-proofing. So I'm going to mount an old-work 4" box in a small piece of plywood and cover the 6" hole with that. The thing is, either way I do it, the top of the light fixture is much more than 4" in diameter, so the connections (from the light to the romex) are nowhere near going to be completely enclosed with fire-resistant materials. Even with new construction, the 4" box would be surrounded with drywall, which I suppose is a bit more fire-resistant than the piece of plywood I'm using, but not that much so.

So, is this ok ? Do I need to cut a piece of tin and attach it to the bottom of the plywood ? Or am I good if I push the wire nuts up into the 4" box ?

 

[gthomas785]

If it's designed to mount to a 4" box then that's all you need. There should be no wires exposed outside the box when you're done unless they are low voltage. Got a picture of this fixture?

 

[bholler]

I am replacing a 6" Halo recessed "can" light with an ordinary surface-mount light designed to mount on a 4" round box.

The half-assed thing would be simply to put in a 4" round box with the adjustable struts designed to position it between to ceiling joists; but that would leave a gaping hole, bad for weather-proofing. So I'm going to mount an old-work 4" box in a small piece of plywood and cover the 6" hole with that. The thing is, either way I do it, the top of the light fixture is much more than 4" in diameter, so the connections (from the light to the romex) are nowhere near going to be completely enclosed with fire-resistant materials. Even with new construction, the 4" box would be surrounded with drywall, which I suppose is a bit more fire-resistant than the piece of plywood I'm using, but not that much so.

So, is this ok ? Do I need to cut a piece of tin and attach it to the bottom of the plywood ? Or am I good if I push the wire nuts up into the 4" box ?

Just cut a ring of drywall as well that will close off the gap

 

[RustyShackleford]

Just cut a ring of drywall as well that will close off the gap

Thought of that. Kind o a PITA.

 

[RustyShackleford]

If it's designed to mount to a 4" box then that's all you need. There should be no wires exposed outside the box when you're done unless they are low voltage. Got a picture of this fixture?

The fixture is flat, with a metal pan top that's may 12" diameter.

I believe NEC 410.23 gives me my answer: "Covering of Combustible Material at Outlet Boxes. Any combustible wall or ceiling finish exposed between the edge of a luminaire canopy or pan and an outlet box having a surface area of 1160 mm^2 (180 in^2) or more shall be covered with noncombustible material."

But I guess the wire nuts themselves (the "connections") still need to be pushed up into the box, they can't just be hanging out in that open area.

 

[gthomas785]

Yeah the fixture is basically acting as the cover to the box. Boxes aren't airtight, maybe there is a gap where a wire could slip out but it shouldn't. Stuff neatly fold the wirenuts into the box and put the fixture up.

As for covering the 6" hole it may be easier to cut out a 16" square piece of drywall and then enlarge the opening to fit the patch. Then tape mud & paint.

 

[gthomas785]

Any combustible wall or ceiling finish exposed between the edge of a luminaire canopy or pan and an outlet box having a surface area of 1160 mm^2 (180 in^2) or more shall be covered with noncombustible material.

A 12" circle has an area of 113 sqin. You're good.

 

[rwhite]

Can you use something like this and allow the halo light to act as the box? These are what came with LED can style lights when I switch from standard bulbs. Then just attach the fixture to the ceiling? I'm no 'trician so take this as spitballing and not a professional suggestion.

 

[RustyShackleford]

Can you use something like this and allow the halo light to act as the box? These are what came with LED can style lights when I switch from standard bulbs.

Yeah, I guess that would work. I already did it though. Just cut a piece of plywood with a hole for an old-work 4" round box. Put it above the drivewall and put a few screws thru the drywall into the plywood. Decided (per above) that the ring of combustible material (the exposed plywood) was acceptable. Made sure to push the wirenuts up in the box though.