Raintight fittings

[pierre]

Bridgeport manufacturing company has now passed the new standard for raintight fittings, and will soon go into production with their new compression fittings. The compression fittings for EMT that will be listed are trade sizes 1/2, 3/4, and 1 inch. Any sizes larger are still not listed.

The fitting is a little different than the ones we are familar with, in that the coupling will have two plastic bushings as well as the 'parts' we are use to. There will be installation instructions and the UL rep told me it will not be difficult to install, just a little different.
You can download the specs from the Bridgeport website if you are interested.

A common question is what to do with the existing fittings you may have, I have been advised to call Bridgeport. GOOD LUCK !!!

Pierre

 

[don_resqcapt19]

Re: Raintight fittings

I don't really understand this issue. The standard EMT compression fittings that are now on the market provide a more raintight connection (in my opinion) than the use of threaded conduit with a coupling. The threaded conduit leaks because conduit couplings are straight thread and not tapered like plumbing couplings. Yes, the conduit itself has tapered threads, but the connections still leak. Are rigid couplings listed as raintight? If not then 225.22 would prohibit the use of rigid conduit in exterior locations.
Don

 

[websparky]

Re: Raintight fittings

UL White Book 2002
Sealing Locknuts ? Sealing locknuts are intended for use with threaded rigid metal conduit and intermediate metal conduit with one sealing locknut in the outside or the inside and either an ordinary locknut or sealing locknut on the opposite side of the enclosure for wet locations
or liquid-tight applications. Sealing locknuts may also be used with Listed wet location or liquid-tight fittings where so marked on the fitting carton.

Hi Don,
RMC and alike have always required these locknuts when "raintight" connections were required. RMC and standard locknuts have never been considered "raintight" much less liquidtight"!

 

[iwire]

Re: Raintight fittings

Dave you have me confused, are you saying we are supposed to put sealing locknuts on both sides of a threaded conduit coupling?

 

[websparky]

Re: Raintight fittings

Hi Bob,

"with one sealing locknut in the outside or the inside and either an ordinary locknut or sealing locknut on the opposite side of the enclosure for wet locations"

The above is referring to enclosures.
No need to be confused!

 

[don_resqcapt19]

Re: Raintight fittings

Dave,
My point is that the code requires "raintight" couplings and in my opinion threaded couplings are no where near as "raintight" as the EMT compression couplings that are no longer listed as "raintight".
Don

[ October 03, 2003, 10:59 PM: Message edited by: don_resqcapt19 ]

 

[pierre]

Re: Raintight fittings

Don

Could that be one of the reasons for "arranged to drain" is found in the raceway article?

Pierre

 

[iwire]

Re: Raintight fittings

Dave I was confused because Don was talking about threaded conduit couplings and your post was about locknuts.

What does one have to do with the other?

Pierre following up on arranged to drain, would that mean if I arranged EMT to drain I would not need raintight couplings or connectors?

I am not try to be a wise guy, but to me Don's question makes a whole lot of sense.

Why is it critical to have raintight EMT couplings and not important for RMC couplings to be raintight?

Would it not be just as effective to expand the requirement that wet rated conductors be used under ground to all conductors in raceways exposed to water shall be wet location rated?

In my experience water always finds it's way in.

 

[big john]

Re: Raintight fittings

This is sorta on the same boat: Arranged to drain; what in the world does that mean?

Does this mean that pipe runs should be assembled so that water run-off isn't likely to enter boxes, e.g.: Coming in the side of a weather-proof J-box instead of in the top.

Or does this mean that the conduits should be arranged so that when water gets into them it will actually be likely to drain out of the run? How would that even work, would you drill holes in the low points of boxes and the like?

Also, is the issue here even the concept that conductors exposed to water may fail if not rated for it? I can't think of a construction job I've worked on where we haven't pulled THHN into conduits that inadvertently filled with water. No one ever seemed to see a problem with that.

What's the deal?
Thanks.
-John

 

[pierre]

Re: Raintight fittings

Don't shoot the messenger

I started this thread for informational purposes, and it has evolved, which is how some of these threads become so valuable for information.
I mentioned arranged to drain, to be the devils advocate, and stimulate some conversation.
I know there are some fittings that are designed for this purpose, but I have never seen them and they may only be for very specific types of installations.
As far as RMC fittings, I do not have an answer for that.
You may want to write to a member of the respective CMP for some resolution on that subject.

Pierre

 

[gwz2]

Re: Raintight fittings

I certainly agree with Don's quest and rationalization.

I noted that a well established code expert notes that RMC installations are watertight, not just raintight.

Again, I agree with Don on this subject and many,many other subjects.

gwz2

 

[bennie]

Re: Raintight fittings

What is the difference between a water pipe coupling and an electrical coupling?


The answer is; nothing.


Before I get trashed, please examine the rolled galv. water pipe couplings, at your local hardware store.

 

[tom baker]

Re: Raintight fittings

Bennie a water pipe coupling has a taper. An electrical coupling is straight. I am an electrician for water utility and have done a lot of plumbing in the past.

 

[bennie]

Re: Raintight fittings

This is an old wives tale. :roll: The couplings with a taper are the cast iron type. The reason for the taper is the fact the thread is cut with a tapered tap. The separation of threads is to prevent the pipe from butting together. A pipe that is touching end to end will leak.

The rolled couplings are tapped through with one tap on one pass, there is no taper.

Like I stated above, check out the couplings.

I have the American Standard for National Pipe Taper Dimensions(NPT).

The fittings with a tapered inside thread are not planned, they are the effect of the manufacturing process.

I will mail a water pipe coupling, with a straight thread, to anyone who will email an address to me.

 

[stamcon]

Re: Raintight fittings

Bennie, this is from the 2000 Uniform Plumbing Code 316.1.1 Threaded Joints - "Threads on iron pipe size (IPS) pipe and fittings shall be standard taper pipe threads in accordance with standards listed in Table 14-1."

Funny thing with this discussion is that I had the opposite discussion with a plumber from AZ on a plumbing forum this morning. He stated that electrical conduit used only straight threads.

 

[bennie]

Re: Raintight fittings

Our plumbing inspector, a man with 25 years experience, came into the inspectors office and announced that he made a pipe fitter throw away all the straight couplings on a large job.

I told him to be sure he had some excess money, to pay for replacing them after the law suit.
He ridiculed me by saying "you electricians use straight thread fittings, the ones on this job were thread protectors", not tapered couplings.

I showed him my ASTM NPT Standards book, he ran back to the job and retracted his correction notice. He quit shortly after that.

 

[iwire]

Re: Raintight fittings

Bennie what type of pipe coupling are you talking about?

I am not busting your chops, the only ones I can picture are black iron, galvanized iron and brass/bronze ones all these I believe are tapered with a separation between the threads in the middle.

I can not remember seeing another type of coupling for water pipe use.

Can you link to a picture or something, I do not know what you mean by rolled.

What type of pipe do these go with?

Bob

 

[bennie]

Re: Raintight fittings

Stamcon: The plumbers use both tapered and straight thread couplings. Electricians use only straight thread couplings with a tapered thread on the conduit.

The thread make up is the same for a plumber as an electrician. A straight thread, in a coupling, will allow the taper thread of the pipe to exert sealing pressure by metal to metal contact, that will sustain substantial water pressure.

A wrench tight fit will be raintight.

[ October 04, 2003, 10:16 PM: Message edited by: bennie ]

 

[bennie]

Re: Raintight fittings

Bob: Pipe is either extruded, cast, or rolled. The rolled type will have a weld seam.

Galvanized steel conduit is rolled, Aluminum conduit is extruded.

It has been a long time since I went to TT school, so don't hold me on these statements.

But I do remember it flows down hill

 

[don_resqcapt19]

Re: Raintight fittings

Pipe couplings with NPT thread are tapped from both ends with a taper tap. The additional cost of making this type of coupling was the reason that the conduit manufacturers got together and successufully changed the Canadian Electrical Code a number of years ago. Prior to this change the CEC required that conduit couplings have a tapered thread. They now use the same straight thread conduit coupling that we do.
look here
Look at the second page of this document for a picture of a ANSI B1.20.1 male and female threads.
Don