Hello All,
I can not find any section in the NEC that talks about the new Rain Tight EMT connectors and couplings. When are they required?

Thank you
Edward

You won't find a specific discussion of this in the NEC. Maybe you'll understand once you know the story.

NEC requires equipment be suitable for its' location. For decades, it was assumed thea this meant compression fittings inwet locations. Then, one day about four years ago, some eager young engineer at UL had the bright idea of actually subjecting compression connectors to the "rain test." The connectors failed. OOPS!

UL responded by releasing a staten=ment that there were no fittings approved for wet locations. Manufacturers responded by re-designing theirs, and submitting them for testing. The new ones have, in theory, been available for two years now.

Just don't tell the local supply house that- they have "never heard of" the new style fittings, and continue to only stock the "unapproved" ones. I have yet to actually see one of the new ones- or have any inspector ask about them. My being in the "high desert" might have something to do with this lack of concern.

From an NEC standpoint, the new style fittings must be used in any wet location.

358.42 Couplings and Connectors.
Couplings and connectors used with EMT shall be made up tight. Where buried in masonry or concrete, they shall be concretetight type. Where installed in wet locations, they shall be of the raintight type.

It may not be true in Reno but one thing is true in Florida.
Wet locations are going to get "wet".
"Rain tight"?
At what wind speed?

Thank you for your input.

Does NEC look at wet location where rain or water will be on the fitting all the time OR NEC looks at ouside as (i.e. on the wall of the building) is considered wet location.

Thanks
Edward

If something is open to the weather it is "wet". Under an awning or porch roof is "damp".

There is going to be some judgement call here.

I have some of the new connectors, but some others have been on back-order long enough that I think my supplier forgot about it. I need to reorder. Per usual I see advertisments and fliers about things like this before the suppliers stock them.

Dave

The actual test for "wet location" stuff is to subject them to an artificial rain, with a pre-determined wind.

Typically, a trough will be set up about 7 ft. above the floor. This trough will have many, many 1/8" holes in the bottom, and a nail inserted into each hole. This causes the water to "drip" off.
A large fan is used to "suck" the rain at a particular angle- if memory serves me, this is about 15 degrees off vertical.
The item being tested is then subjected to this "rain" for a set period. "Passing" criteria vary somewhat by item, but the intent is to establish that there is no hazard created. Generally, some water entry is allowed.

Its more a listing thing rather than a code thing. NEC requires RT, but its listing that allowes it to be RT.

My understanding is that the old style compression fittings are still listed RT in Canada. Not sure if that will hold water...

The new style have been slowly hitting the supply houses here, and I have a stash of them in the van right now, I like 'em. Pricey, but nice. Ya gotta be nice putting them together, if you're too aggressive you'll find that O-ring stuck in the connector during your pull. Not a fun find.

Every time this comes up, I say this. I don't understand the issue here. The old EMT couplings are more raintight than threaded rigid couplings. Why is it a problem when the inside of the EMT is wet, but not when the inside of the rigid is wet?
Don

We did a job replacing a ton of conduit on a buildings roof a couple years back. Inspector tagged us for not using the newly approved RT connectors. We ordered some and redid all the work. He then retags us saying his town only allows one manufacture of RT fittings. So we redid the work again =\

Now there are several manufactures that inspectors around here will accept, was just a fustrating learning process for us.

You can tell the difference between the fittings, the approved ones have colored plastic bushings everywhere. Also you can tell the difference when you get the price for the new ones

Shhh resqcapt19, don't give UL any ideas! They might remove rigid's aproval as RT!

Don,
My rigid connections are greased, and tight, bone dry in there. Some grease, Corroision-X, or Noalox and a 2' handle chain wrench will help to get it tight enough to run gas through, not that you would.

Just thought of something, do they make "New" Treadless RMC connectors and couplings with gaskets on them too?

What does a rain tight MC fitting look like? How do you keep the water out of the MC cable?

gfretwell, RMC/Rigid Metalic Conduit, there was an "R" in there.... If thats what you mean?

No not RMC, MC.
MC cable is usually labelled wet or dry. What type of connector do you use if you are a fanatic about the rain tight thing?

MC in the rain.......... Sounds like a bad idea.

You may not like it but
330.10(A)(12) In wet locations where any of the following conditions are met:
a. The metallic covering is impervious to moisture.
b. A lead sheath or moisture-impervious jacket is provided under the metal covering.
c. The insulated conductors under the metallic covering are listed for use in wet locations.


I am looking at a box of aluminum wound Southwire EZ-MC that says it has THWN conductors suitable for wet locations.

My question, with what rain tight connector?
You seen one? How does it stop the water inside the MC cable?

e57,
Conduit couplings are straight thread, and do not seal even when made up wrench tight. A compound such as required by 300.6(A) may help, but it is my opinion that rigid conduit couplings are less raintight than the old EMT couplings. I think that our couplings should have tapered thread like the plumbers couplings do. This would make them more water tight and provide a better fault clearing path.
Don

Here is some UL information
http://www.ul.com/regulators/raintight.cfm

I am holding in my hand a box of leftover O-Z/GEDNEY compression emt couplings , cat # 6125s. They were from a project I did in the mid 1980's. Right under the UL label is the statement "Suitable for wet locations. Concretetight." Seems to me that at some point in the past UL did in fact test and label compression connectors and couplings for wet locations. At least some brands anyway.

I still don't understand the sudden interest in "rain tight". Wet locations imply water will enter the wiring compartment. That is why you need "wet" rated insulation on the wire.
Once we get the EMT/box junction sealed, are we going to start working on the box covers?
How long do you figure it will be until we can stop drilling holes in the boxes to let the water out?

Maybe they should do the testing with a pressure cleaner for us folks who live where the wind blows while it is raining.

I think the new standard came about when UL's testing lab got an updated water system and new hoses.

Now, read the following for something to think about.

225.22 Raceways on Exterior Surfaces of Buildings or Other Structures;
Raceways on exteriors of buildings or other structures shall be arranged to drain and shall be raintight in wet locations.

What?

Roger

I suppose some areas on the exterior are not considered wet areas, like tight under a soffit.

Dave

Dave,
Then why shall it be arrainged to drain?

If there is enough condensation to drain, it's wet.

If it's raintight, does it not need to drain? I would say there is a better than average probability for condensation inside of a raintight installation, wouldn't you?

Roger

When this one hit the pipes two years ago my thought was - great another overblown fix to another non problem.

Last 07/06, we had a discussion going about a pic of "MC Cable Outdoors."

NEC says MC can be in a wet location, BUT...every connector I've seen is marked "dry location only." So I guess that the cable is OK, but any connections are another matter.
BTW, this is one of the code differences between MC and AC.

The construction difference in dry location cables seems to be the paper wrap inside. It wicks up water.
Damp and wet cables seem to have a plastic wrap or none at all.

Simple plan--

Use FMC and insulation with a 'W' in the designation for your conductors.

Now just convince the inspector it is not subject to physical damage and you're good.

If this is ok what difference does it make if water gets in rigid or emt as long the wires are wet rated? It may not drain as readily?

How do you arrange a raceway to drain and install it in a workmanlike manner? If it is sloped I know many people who say it is not done in a workmanlike manner. (Unless of course the wall was built sloped)

Steve, I once worked in a packing house....that is, a place where cows entered one end, and burgers, sausages and the like exited the other end.
A packinghouse is divided into two types of rooms- refrigerated, and frozen. Everything gets steam-cleaned daily. Can you imagine a better place for condensation to form?

Anyway, if we did not allow for drainage, the lines and boxes would get the most amazing crud in them. Our typical solution was to enter boxes from above, and to have a 'weep hole' in the bottom of the box. Conduit was run in the usual level/ plumb manner.
Still, I can recall several times a pipe was found to be filled with water. When this happened, well, we didn't worry about it over-much.

I'm not convinced that condensation would be an issue with conduit tight to a soffit, Roger. Condensation usually occurs with varying temperatures inside and outside the pipe. IMO the temperature would change gradually and equally.

Why drain a dry pipe? As an added precaution.

I'm in agreement with you that the wording is a little strange, but who reads the NEC without getting used to that?

Dave

Dave, how can an installation be arrainged to drain if it's raintight?

The new fittings are supposed to be absolutely water tight, yet the wording of 225.22 tells us to provided an opening in the raceway.

Whether it's due to condensation, water pressure, or flooding, the point is, there will be moisture in the raceway and the NEC recognizes it, this is why we use "W" type conductors.


Roger

[This message has been edited by Roger (edited 08-27-2005).]

I take the phrase "arrange to drain" to mean that you have one end of the pipe lower than the other as a plumber would with a horizontal run of drain pipe. Everything we use outside can get wet inside, so it needs to drain. That doesn't mean that we want it filling up with water like a plumbers drain, as I guess it was with the old type fittings. I was stating in my earlier post that I might not consider all locations outside to be wet locations.

Looking from another perspective, those old fittings were also letting the water drain back out. As you say, the only real safeguard is that the insulation is rated for a wet location.

Dave