Light fixture box for conduit

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Old 10-20-09, 07:26 PM
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Light fixture box for conduit

I'm running wiring in the interior of a garage in conduit and want to install a nice exterior light fixture outside the front door. As I understand it, the conduit needs to end at the fixture, meaning it has to run through the wall to the fixture.

The only kind of round wiring box I can find that works with conduit is the metal kind with threaded conduit holes that has two screw mounting brackets at the bottom (the side that is closed) . Is there a standard way to mount this kind of box on the interior side of a plywood wall? If it had the screw brackets towards the front (the open end) it could be mounted to the inner side of the siding. I realize it would work on the outside of the wall but that will look like hell.

Is there a type of box that mounts on the inside of a wall/sheathing that also attaches to conduit?
 
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Old 10-20-09, 08:03 PM
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By the sounds of it you have access to the inside of the walls. I suggest getting some steel 4x4" boxes with a bracket on the side to attach to the side of a stud. (or framing you add to get it in the right place) Then get a square to round mud ring that is raised the thickness of your wall sheathing. Most Big box stores will carry 1/2" or 5/8" so if your sheathing is a different thickness you may have to hit a supply house. Cut a hole in your sheathing/siding the size of the mud ring and you good to go.
 
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Old 10-21-09, 08:23 PM
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Sorry I didn't mention PVC previously. The problem is that something has to attach to PVC conduit. Are there mud rings that fit the round metal boxes with threaded holes? That's the only thing I can find that fits PVC unless it's the PVC boxes, but they have the same problem - no way to attach to inside of wall.

You said a square box with a square-to-round mud rign - fine but if you ayou talking about the new work boxes with holes for cable, that won't work. I need to attach to the box with the PVC conduit.
 
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Old 10-22-09, 05:33 AM
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There are locknuts made that will hold the threaded PVC male adapter into standard knockouts in a non-threaded metal box. They should be easily available.
 
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Old 10-22-09, 11:24 AM
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This is my understanding--- you are running PVC conduit fastened to interior side of an exterior wall in the garage, and you need to extend the conduit 90 degrees thru the wall into the rear of an exterior oulet-box.

If this is correct, all you need is an "LB" fitting.
 
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Old 10-22-09, 06:35 PM
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I plan to use an LB to make the turn where it enters the wall. Then there will be a length of PVC through the wall that needs to attach to the box. I suppose I can install some blocking, but it's just hard to believe there's no standard solution for this problem.

I was unable to find at HD or Lowes the locknuts that pcboss suggested or the square to round mudrings.

It's exactly the same situation you would have if you tried to install a ceiling fixture or fan but the wiring upstairs was in PVC conduit. You'd have no problem finding a box designed for cable that you can nail to a stud, or that has brackets, but how would you connect the box to the conduit?
 
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Old 10-22-09, 08:26 PM
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OK \. I understand your project better.

Here is a locknut: Conduit Locknuts

It attaches to the threads of the PVC male adapter which goes into any 1/2" KO of just about any metal box and some plastic ones too: http://images.cableorganizer.com/can...dapter-120.jpg

You can then come into the back of a steel shallow pan box like this (this one is only a 1/2" deep: http://ec-images.acehardwareoutlet.c...011708I_mk.jpg You can recess this into your siding and attach to the sheathing.

Other options: Siding Box Kits
Siding Box Kits
Siding Mounting Kits with Built-in Box

Again, all these boxes can be attached to using the male adapter and a locknut.
 
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Old 10-23-09, 08:43 AM
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Sweet! I feel like the caveman discovering the stick in 2001.

Thanks all for hanging in there.
 
 

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