How do I weatherproof security floodlamps to follow NEC?

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  #1  
Old 03-25-06, 09:51 PM
assemblage
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How do I weatherproof security floodlamps to follow NEC?

I'd like to install two motion floodlamps under the eaves of my house. The light kits come with gaskets. I'd like to install them using the retrofit ceiling boxes, pass the wire through the attic to the eaves, use 12/2 NM wire and use the normal yellow wire nuts. Is this the way I should do it to be following the NEC? Is there any tricks that would help keep these watertight?
 
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  #2  
Old 03-26-06, 05:32 AM
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Originally Posted by assemblage
Is there any tricks that would help keep these watertight?
If you are mounting these on the soffit, that is with the cover plate facing the earth (the grass, dirt,driveway, whatever), I would advise against making the coverplates watertight. I did this and used electrician's putty to plug my Greenfield (flex) fitting in the back of the box to seal the connection into the house.

One day I noticed water dripping from one of the boxes so I opened it up (with power off!) and poured out a whole bunch of water. The chunk of electrician's putty had fallen out of the fitting and was laying on the cover plate. Same thing with the other box. A third box was OK, maybe because I used putty on the fitting in the attic box too, or because I used more putty, although flex is not airtight.

On reflection I realized there was not much reason to seal a plate facing down since this would prevent gravity from helping me keep the boxes dry.
 
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Old 03-27-06, 08:40 AM
assemblage
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Thanks for the reply. The security light comes with a gasket to use. It says to use caulk if you don't use a "weatherproof" box.

At Lowes and Home Depot, the only "weatherproof" boxes I see are ones that use conduit, like this one by Carlon. These seem to be rather difficult to mount in exisiting construction. It looks like it's meant to mount on the outside of the structure.

It seems the Carlon retrofit ceiling boxes (the one where the wings come out and cinch as you turn the screws) would provide a much better support structure for the light fixture. The bottoms could be sealed using the gasket & caulk method mentioned by the light manufacturer. The tops would not be sealed though. But they aren't exposed, they are under the roof.

Does it follow NEC guidelines to use the retrofit box?
 
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Old 03-27-06, 06:04 PM
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Yes, you can use the "retrofit" box (known as an "old work" box), if you have the room, and the soffit material will allow it (vinyl soffits?). If the box is recessed into the soffit, as with an old work box, the box does not need to be a weather proof box. You don't need a gasket, but I would use one. I don't expect water to get into the box, but I do want to keep out bugs.
A weather proof box usually has threaded female connections that can be used with conduit or a waterproof Romex connector (or even a regular Romex box connector).
If you have a typical single family home, in the US, you can use regular NM cable to the box.

I don't understand how water got into ArgMeMatey's boxes under the soffit.
 
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Old 03-27-06, 07:43 PM
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Originally Posted by fixitron

I don't understand how water got into ArgMeMatey's boxes under the soffit.
Yeah, I should have been more clear about my theory. My putty fell out of the fitting, and the more humid air from inside the house flowed through the flex to the cold box. Moisture condensed and voila, box full of water, sealed in by gasket but slowly leaking out.

This should not be a problem with NM and a slightly ventilated plastic box, especially if the box is mounted flush with the soffit, where it would presumably not get as cold.
 
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Old 03-28-06, 05:36 AM
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Thanks a lot for the information.

The soffit is about 1/8" and plywood. Over that is the vinyl siding.

I supposed if I used the weatherproof box, I wouldn't recess it but screw it on the plywood. Since the plywood is so thin, I'm not confident the screws would stay in the plywood over long term. The "old work" box would be more stable.

I saw weatherproof wire nuts at the store. I suppose those would be good to use in the application.

Now that you mention it, I wonder how to sandwhich it in. With a recessed "old work" ceiling box, is it:
1) plywood -> box lip -> siding -> gasket -> light
or
2) plywood -> siding -> box lip -> gasket -> light
 
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Old 03-28-06, 06:37 AM
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Is your vinyl soffit corrugated? If it is, you might consider using a weatherproof octagonal box. Consider using a PVC accessory, I can't recall what they are called, that is square and is designed for mounting outlets, lights or even hose bibbs to. Put the box up against the soffit, centered on a rafter tail, and mark it. Cut through the vinyl soffit only where you just traced. Take a 1¼"-1½" spade bit or hole hog bit, or use a recip. saw and chisel, and make a notch in the center of the plywood hole that is about 2" up into the rafter tail. This will allow you to screw in a regular NM cable box clamp into the back of the weather proof box. Then screw the box to the rafter tail. Cut the 4" square PVC trim piece to just slip over the box (and hide the mounting tabs sticking out of the box).

Otherwise, don't worry about the gasket and sandwhich the plywood and vinyl soffit between the old work box flange and the clamps.

Don't bother with waterproof wire connectors. As long as the connectors are tight, regular wire nuts are fine.
 
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Old 03-28-06, 06:48 AM
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Originally Posted by assemblage
Thanks a lot for the information.

The soffit is about 1/8" and plywood. Over that is the vinyl siding.


I saw weatherproof wire nuts at the store.

Now that you mention it, I wonder how to sandwhich it in. With a recessed "old work" ceiling box, is it:
1) plywood -> box lip -> siding -> gasket -> light
or
2) plywood -> siding -> box lip -> gasket -> light
Old work would be best then, but if your soffit is that thin I have to wonder if the weight of the assembly will cause it to sag over time. You many want to look for a rafter end or add some bracing inside.

Weatherproof wire nuts won't hurt but unless you're expecting a situation like mine, you can get by with regular ones. Just point the open end toward the ground if possible.

Use your #2 option. Having put a number of these Carlon boxes in lath and plaster, I use a 3-1/2" hole saw and then use a drywall saw to notch the spots for the wings and protrusions. I've also done it the hard way with a sawzall and by drilling around the perimeter, and those are a lot harder.
 
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Old 03-28-06, 07:25 AM
assemblage
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Thanks again. I'll be doing the work the weekend after the coming weekend. I didn't think about the plywood sagging. I'll have to reexamine my mounting options when I get up there. That sagging would definately keep me from using the "old work" box. But thanks to you two, now I know my options.

I really don't know my vinyl siding, my siding is sheet like... it's formed to look like wood planking but it's just thick plastic.It looks like this stuff.. If there is an accessory for mounting light fixtures, that would be good if I don't use the "old work" box, but where would I find it if not at Lowes or Home Depot?
 
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Old 03-28-06, 08:09 AM
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I didn't find any on the Owens Corning site. Look about halfway down this page:
http://www.taunton.com/finehomebuild...ges/h00110.asp
 
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