How to attach EMT offset connector to weatherproof box

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  #1  
Old 08-04-12, 10:54 AM
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How to attach EMT offset connector to weatherproof box

Hey gang,

I am installing a security floodlight on an outside stucco wall. The power source is from an existing, unused weatherproof box that is mounted flush onto the stucco wall. It looks like this:

[ATTACH=CONFIG]2415[/ATTACH]

I am using EMT conduit to run the wiring, and it will run flush along the wall. Therefore, I understand I will need an EMT offset connector to take up the slight bend where the flush-mounted conduit needs to go into the not-quite-flush knock-out on the box. Here is the EMT connector I bought:

[ATTACH=CONFIG]2416[/ATTACH]

My question is, how do I attach the EMT offset connector, in a watertight fashion, to the box? Most FAQs I've seen assume you are using a metal box like this:

[ATTACH=CONFIG]2417[/ATTACH]

For this kind of box, you can just put the offset connector thru the knock-out with some washers (I assume) and then thread a nut onto the EMT offset connector from the inside to cinch it down. However, the boxes I am dealing for the power source and where the lamp mounts are much thicker, as pictured above. The knock-outs are actually threaded, such that the EMT offset connector threads into them.

Am I using the wrong kind of box for the job? Or do I just need to get creative? I'm thinking of caulking the threads of the EMT offset connector before I screw it into the threaded knock-out until; then, once the conduit run is assembled and strapped down, go at it with some extra caulk.

When all is said and done, I plan to drill a 1/8" hole in the bottom of the two weatherproof boxes (the power source, and the one the security light will mount onto), because I suspect they will still accumulate moisture over time, and it needs somewhere to drain.

What are your thoughts? I can post pictures when I'm done. Thanks for your help!!
 
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  #2  
Old 08-04-12, 12:03 PM
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Best to use PVC conduit not EMT outside. In the case of PVC use a PVC weather tight box and a PVC offset.
 
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Old 08-04-12, 01:24 PM
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You are going to need to use a weatherproof box outside. The second box pictured is for indoor only.

You can put caulk on the threads before screwing in the offset. You could also bend an offset in the EMT and avoid an extra fitting.
 
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Old 08-04-12, 06:02 PM
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You have a picture in your post of an offest nipple (sometimes called a gutter nipple), not an EMT offset connector. I prefer the conduit have an offset bent in it, but many DIYers are not accomplished benders of conduit and prefer to use a compression offset connector like this.

1/2" Die Cast Zinc Offset Compression Connector

There is no need to caulk the threads of the connector where it screws into the threaded hub on the box.
 
  #5  
Old 08-05-12, 12:18 AM
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Thanks for the info, guys. It sounds like I should pick up a true EMT offset connector, and give it a try. I think the guy at the lighting shop must have grabbed the wrong thing; he was super helpful with everything else though.

My Home Depot book suggested using EMT rather than PVC for outdoor runs that are more than 6" above-ground, so I thought I'd give it a try and see how it worked out for me. PVC would have been a lot easier, but I wanted the chance to play with this EMT stuff.

And yeah, bending my own offset in the conduit sounds like fun but I just gotta get this done so I'll probably go for a 'real' EMT offset connector.
 
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Old 08-05-12, 07:09 AM
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My Home Depot book suggested using EMT rather than PVC for outdoor runs that are more than 6" above-ground, so I thought I'd give it a try and see how it worked out for me. PVC would have been a lot easier, but I wanted the chance to play with this EMT stuff.
Personally, I don't like the looks of PVC conduit run exposed either and would also use the EMT with compression connectors, but it will eventually rust depending on exposure to rain and sun. I've seen EMT last 30 years on the side of a building before rusting, but I've also seen it rust in as few as 5 years when used on a rooftop. There is an easier way to run EMT without using the offset connectors or bending an offset at each box. If you use simple conduit hangers (commonly called Minnies) the conduit is held the proper distance from the surface and can enter the Bell boxes directly with no offset required. Take a look at these:

Steel City 1/2 in. Conduit & Pipe Hanger with Bolt, 6H0-TB - Crescent Electric Supply Company
 
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Old 08-05-12, 11:31 AM
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Some big box stores carry prebent 1/2" EMT box offests. Then you just need to use a standard compression connector.
 
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Old 08-05-12, 05:04 PM
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Done! Pictures

Thanks for your help. I just finished it off, works great.

Here is the overview -- but first, I have to share this: I was getting ready to crawl under the house to find an existing connection I could tap into, and then I saw an old rusty electrical box about 8 feet from where I needed the light, that I had never really noticed before. I opened it up and put a tester on it; turns out, it worked fine and was controlled by a switch in our dining room that had been a mystery to us in the 8 years we've lived in our house! That kind of stuff only happens to other people, right? Quite serendipitous. I put a new box on it.



Here's the box, along with the sweep section, two rain-proof couplers, and one of the awesome brackets ("Minnies") that prevented me from having to deal with an EMT offset connector.



Here's a shot where I tried to show how the bracket holds the EMT conduit exactly the same distance from the mounting surface as the pre-cut threaded knock-out on the electircal box:



Just gotta wait til it gets dark to tweak the sensitivity of the lights, and I'm good to go.
 
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Old 08-05-12, 08:31 PM
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Thanks for your help. I just finished it off, works great.
Looks great, too! One little thing, though. You need a few more Minnies. One on the straight run from the box and two on the vertical run to the light.

There needs to be a strap within 24" of each box, IIRC, but keeping it to 12" or so is preferable. Then, on the vertical run, there needs to be a second strap w/in 48" (again, IIRC) of the one near the light.
 
  #10  
Old 08-06-12, 03:28 PM
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1/2" EMT is required to be strapped 3' (or 5' if there is nothing to attach to) from a box and every 10' max in between. 358.30(A) (2008)
 
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Old 08-06-12, 05:25 PM
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Hmm, it sounds like my straps happen to fall into the requirements, though just by chance. Which is good, because I'm not about to de-couple the conduit sections to install more straps! I will keep in mind for my next install though.
 
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Old 08-06-12, 10:15 PM
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Must be some I can't easily see.
 
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Old 08-06-12, 10:30 PM
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I think you're right actually, I probably should have one near the box on the top. Oh well, hopefully it won't pop off the wall anytime soon!
 
  #14  
Old 08-07-12, 08:59 PM
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Originally Posted by CasualJoe View Post
Personally, I don't like the looks of PVC conduit run exposed either and would also use the EMT with compression connectors, but it will eventually rust depending on exposure to rain and sun. I've seen EMT last 30 years on the side of a building before rusting, but I've also seen it rust in as few as 5 years when used on a rooftop.
I ran PVC to power my shed not even two years ago, and it seems that it can't take the exposure to the sun/heat (it is underground/above-ground/sunlight rated conduit). The LB has completely "rusted" (as has the male threaded adapter) and is starting to deform. The cover gasket has completely disintegrated, and the conduit itself is also showing signs of discoloration/deterioration. The joint between the conduit and LB has also broken loose because the cement cooked away (there is an expansion joint). It's bizzarre, I've never seen anything like it.

 

Last edited by JerseyMatt; 08-07-12 at 09:18 PM.
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