Connecting emt to nonmetallic flexible conduit (type B)?

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Old 04-29-11, 07:10 PM
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Connecting emt to nonmetallic flexible conduit (type B)?

I got the raised eyebrows (over the phone) from the supply house I deal with regarding a connector to mate emt to nonmet. flex conduit. He said that they don't carry the part because they make their own in house out of on hand parts. He said something about just connecting the malleable iron with another connector and use that together.... I was thinking that it's probably not UL listed for that purpose and its probably not raintight which is what I had asked for originally.

This needs to be watertight. About the best I could figure (without ordering the correct part which is a Topaz #12270 or 272) was to use a threaded coupling with a emt raintight on one end and a type-B raintight on the other.

So what do you use to join 3/4" emt to carflex?
 
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Old 04-29-11, 07:19 PM
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So what do you use to join 3/4" emt to carflex?
To make it raintight, use a 3/4" EMT compression connector and a 3/4" PVC female threaded adapter. The compression side attaches over the end of the 3/4" EMT and it then threads into a 3/4" PVC female threaded adapter. The 3/4" Carflex glues inside the socket of the female threaded adapter with PVC cement. All supply houses should have these in all the same sizes as PVC conduit.

Amazon.com: Carlon E942N 4" Female Adapter Pvc Conduit Fitting: Industrial & Scientific
 
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Old 04-29-11, 07:48 PM
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If you use nonmetallic flex (or flex longer than 6') you will have to pull in a ground wire.

I suggest using a 3/4" rigid coupling with an EMT connector on one side and a flex connector on the other. I'm pretty sure PVC female adapters are not listed to be glued to Nonmetallic flex conduit.
 
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Old 04-29-11, 07:51 PM
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And I know that this seems to be common practice, but check out bottom of page 4 http://www.carlonsales.com/techinfo/...iquidtight.pdf manufacturer doesnt condone it and I am sure its not UL listed.
 
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Old 04-29-11, 08:00 PM
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Originally Posted by Tolyn Ironhand View Post
If you use nonmetallic flex (or flex longer than 6') you will have to pull in a ground wire.

I suggest using a 3/4" rigid coupling with an EMT connector on one side and a flex connector on the other. I'm pretty sure PVC female adapters are not listed to be glued to Nonmetallic flex conduit.
Thanks Tolyn. Is this something you have seen done before?
 
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Old 04-29-11, 09:15 PM
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I thought I read in the code something about having to use a box when transitioning between flex and emt. Those connections without boxes also look like crap and an accident waiting to happen in my opinion.
 
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Old 04-30-11, 05:45 AM
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Originally Posted by Tolyn Ironhand View Post
If you use nonmetallic flex (or flex longer than 6') you will have to pull in a ground wire.

I suggest using a 3/4" rigid coupling with an EMT connector on one side and a flex connector on the other. I'm pretty sure PVC female adapters are not listed to be glued to Nonmetallic flex conduit.
Oops! That's right, I was thinking smurf tube (ENT) when I answered that. I have to agree, do not glue Carflex into a PVC socket. I also agree with TI that a ground wire is required, but I have to disagree on using the rigid coupling. Rigid couplings are not U.L. Listed to be used with EMT as a threaded adapter, but to be used to join sections of rigid threaded conduit.
 
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Old 04-30-11, 05:49 AM
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Originally Posted by Justin Smith View Post
I thought I read in the code something about having to use a box when transitioning between flex and emt. Those connections without boxes also look like crap and an accident waiting to happen in my opinion.
I think you are right in some situations, but not all. There are combination couplings (sometimes called Go-To) available to transition between EMT and flex conduit for certain fixed equipment that is required to be able to flex or that vibrates. A good example of this is wiring an electric motor.
 
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Old 04-30-11, 06:24 AM
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From the page the OP linked to:

Can you glue Carflex directly into Carlon PVC fittings?
Sorry, but fittings are not allowed to be glued or solvent-cemented to Carflex
directly. Only a mechanical connection is allowed and you can only use
Liquidtight Flexible Nonmetallic Type B fittings with our Carflex.
Calling it a rigid coupling might be the wrong. We call them a tomic coupling. It might be a local thing but the supply house knows what we are asking for. I'll post a picture of one as soon as it stops raining.
 
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Old 04-30-11, 11:34 AM
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I would love to see what your thinking about. The only thing I could find called tomic was a tomic connector, like a tip in for dryers
 
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Old 04-30-11, 11:41 AM
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Rain has stopped

Oooo I hate those connectors No, that is not it.

Here is the fitting we call a tomic coupling:



Note: we have used these all the time in sizes ranging from 1/2" to 1 1/4" and no inspector has ever said that it is an improper fitting.

Here is an assembled set of fittings using a 3/4" EMT set screw connector (You will need a compression) the 3/4" tomic coupling and a 3/4" LFNC 90 degree connector.



I have an extra coupling I can sell you for $20
 
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Old 04-30-11, 11:58 AM
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Sold your advice alone is worth it, lol. I hate those connectors too... I have seen so many of those improperly torqued b/c they are so flimsy going in everyone feels the need to make sure they're tight.... That tomic coupling looks just like a rigid coupling! How long is the tomic coupling overall? (between the o-ring and set screw conn.) thanks
 
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Old 04-30-11, 12:06 PM
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That is why I called a rigid coupling but they are not as long. It is only about 3/4" long. (1/2" are the same length.) They are rigid threads as all connectors, locknuts, bushings, etc. are rigid threads. When the fittings are screwed in on each side they meet in the middle.

Again, make sure you pull in a ground if your using non-metallic flex.
 
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Old 04-30-11, 12:13 PM
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Very cool, thanks for the info. Maybe that's what the supply house was referring to as a malleable iron coupling. It seems to be common practice here as well. Thanks again

p.s. - If this is the same 3/4" Zinc Plated Steel Short Threaded Coupling they call them short couplings
 
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Old 04-30-11, 01:08 PM
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Looks like the right one. Good luck!
 
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Old 04-30-11, 05:41 PM
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Interesting, I am not familiar with those, but I don't think they'd pass muster here as they are still a rigid coupling and listed under Rigid and IMC Fittings.

Application:
These short threaded couplings are used with chase nipples to provide short raceways and connections between electrical boxes that are mounted on fixed position mounting brackets made by Erico, B-Line or Minerallac.

Advantages:
Garvin Industries’ short threaded couplings allow wires to be easily pulled from one box to the other box on a fixed-position, wall-mounting bracket. Their perfect length fills the space between boxes and gives solid support and a secure bond to connectors and boxes. They are available for 1/2”, 3/4” and 1” box knockout sizes.

Field Names:
Rigid couplings, threaded rigid couplings, heavywall couplings, threaded heavywall couplings, rigid couplers, heavywall couplers, threaded couplers, short couplings.
As always, the AHJ has the final say. Good luck with your project!
 
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Old 04-30-11, 06:43 PM
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I saw it too CasualJoe, and I doubt it would get a UL listed approval, but what else can you do aside from order the exact part. I was just curious to see if there were other opinions on how to get it done and to see how prevalent a practice it is. The correct part is made be bridgeport 4361-dc and topaz 272
 
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Old 05-01-11, 07:40 AM
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Originally Posted by chopnhack View Post
I saw it too CasualJoe, and I doubt it would get a UL listed approval, but what else can you do aside from order the exact part. I was just curious to see if there were other opinions on how to get it done and to see how prevalent a practice it is. The correct part is made be bridgeport 4361-dc and topaz 272
I am sure the practice of using a rigid coupling to make a transition is quite prevalent in most areas, it's definitely raintight (not water tight) and isn't an issue at all unless this work is to be inspected by a particularly anal inspector. It used to be an accepted practice in my area to use a rigid coupling to make all sorts of transitions in place of combination couplings (sometimes called a Go-To) bewteen EMT and flexible metallic conduits too, but is no longer allowed because of the U.L. Listing. Is your job to be inspected? If so, consult the AHJ and ask, it's most likely not an issue, just a technicality. I am not familiar with Topaz, is that an import?
 
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Old 05-01-11, 11:44 AM
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Originally Posted by CasualJoe View Post
I am sure the practice of using a rigid coupling to make a transition is quite prevalent in most areas, it's definitely raintight (not water tight) and isn't an issue at all unless this work is to be inspected by a particularly anal inspector. It used to be an accepted practice in my area to use a rigid coupling to make all sorts of transitions in place of combination couplings (sometimes called a Go-To) bewteen EMT and flexible metallic conduits too, but is no longer allowed because of the U.L. Listing. Is your job to be inspected? If so, consult the AHJ and ask, it's most likely not an issue, just a technicality. I am not familiar with Topaz, is that an import?
No inspection job valued under $100. I just don't ever want to have an issue where an insurance company comes back and says "it wasnt UL listed so your claim is invalid..." We have a real hard time in florida with insurance companies.

Here is a link to the bridgeport model Frost - BRIDGEPORT 4361-DC 3/4IN METALLIC OR NONMETALLIC LIQUID-TIGHT TO 3/4IN EMT COMBINATION COMP COUPLING (CONCRETE-TIGHT / RAINTIGHT)

and the topaz model TOPAZ 272 EMT TO LIQUID TIGHT CONDUIT COMBINATION COUPLING*::*EMT TO LIQUID TIGHT FLEXIBLE METALLIC CONDUIT COMBINATION FITTINGS *::*EMT COMBINATION FITTINGS *::*EMT FITTINGS *::*CONDUIT ACCESSORIES *::*Edwards Supply Co., Inc.

I am sure that a little silicone can make that connection permanently raintight
 
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Old 05-01-11, 04:28 PM
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Silicone isn't necessary to make a rigid coupling raintight. I was just pointing out that rain tight and water tight are two different things. If you are concerned about U.L. Listings, why not just order the Bridgeport fitting? Actually, I've never seen one used, but am impressed at Frost for stocking them. Frost is a great little supply house.
 
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Old 05-01-11, 08:25 PM
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Can you explain the difference between watertight and raintight? This connector will end up being below grade. Ordering the item is not out of the question, just a little pricey, I was mostly interested in what electricians around the country were doing on a daily basis. Thanks again.
 
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Old 05-01-11, 08:40 PM
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I showed you what we do and all has been blessed by the inspectors around here.

Watertight NEC definition = Constructed or protected so that moisture will not enter the enclosure (or fitting) under specified test conditions.
My note: It could be submerged in water

Raintight NEC definition = Constructed or protected so exposure to a beating rain will not result in the entrance of water under specified test conditions.
 
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Old 05-01-11, 08:59 PM
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I do not think LFNC or that bridgeport fitting are rated for direct burial.
 
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Old 05-01-11, 09:28 PM
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Originally Posted by Justin Smith View Post
I do not think LFNC or that bridgeport fitting are rated for direct burial.
Who said anything about direct burial?
 
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Old 05-01-11, 10:15 PM
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I mentioned that it would be below grade, but carflex is rated for direct burial. As for the bridgeport, I havent looked it up yet. Thanks for the clarification Tolyn. Thanks again all for the input

You are correct on the bridgeport Justin, best I could find is that it is just raintight, doesnt say watertight therefore not necessarily for below grade. I guess at this point its really splitting hairs, I am satisfied with the research and the great suggestions by all :-)

One other follow up question, does it really matter if its watertight per say when your running THWN wire?
 

Last edited by chopnhack; 05-01-11 at 10:31 PM.
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Old 05-02-11, 10:11 AM
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Below grade does not necessarily need to be watertight, just rated for use below grade. Some carflex is rated for burial, so you're probably okay there. "Watertight" and "raintight" are usually used more to describe panels and boxes than conduits since it is pretty much guaranteed that water will get into any outdoor conduit. Raintight should be able to withstand normal precipitation fall without getting the inside of the box wet, it can often be open on the bottom. Watertight is for something like a car wash bay or pumping facility where it's likely the electrical equipment would be sprayed directly with liquid, it will be a solid box with rubber gaskets. Chop, I think the plan you have it just fine.
 
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Old 05-02-11, 01:17 PM
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Originally Posted by chopnhack View Post
I mentioned that it would be below grade, but carflex
My apologizes Justin, I missed that part.
 
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Old 05-02-11, 06:12 PM
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I could see that bridgeport being dug up a few years from now all corroded
 
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Old 05-02-11, 06:50 PM
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I mentioned that it would be below grade, but carflex is rated for direct burial. As for the bridgeport, I havent looked it up yet. Thanks for the clarification Tolyn. Thanks again all for the input
I'd be more concerned with the 3/4" EMT being below grade. EMT has a very limited life underground and isn't normally used for that application.
 
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Old 05-02-11, 06:54 PM
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One other follow up question, does it really matter if its watertight per say when your running THWN wire?
Not really. Most, if not all, underground conduits have water in them. Some engineers specify XHHW wire for all underground and underslab circuits, but in my opinion, THWN performs just as well.
 
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Old 05-02-11, 07:32 PM
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Originally Posted by Justin Smith View Post
I could see that bridgeport being dug up a few years from now all corroded
For that matter Justin, the compression fitting for the emt is made from the same material... I have to rethink this, or perhaps just encase the connection in concrete?

Casual Joe - I didn't realize that conduit often ended up with water inside. Pretty interesting, but it makes sense, the threads aren't like plumbing threads that have bevel to them. There would only be a short stub coming out of the cmu wall, then the fitting followed by carflex.
 
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Old 05-02-11, 08:01 PM
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I'd be more concerned with the 3/4" EMT being below grade. EMT has a very limited life underground and isn't normally used for that application.
Like this? http://www.doityourself.com/forum/el...cal-lines.html
 
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Old 05-03-11, 10:23 AM
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Originally Posted by chopnhack View Post
the threads aren't like plumbing threads that have bevel to them.
The threads are the same as plumbing threads (NPT standard) but you do not use any thread compound (pipe dope, teflon tape, etc) on electrical connections because it breaks the grounding path so the threads don't seal fully. Outdoor conduits are also subjected to condensation so some water will collect in there just because humid air can get into the pipe.
 
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