UL listed emt fitting for a wet location (watertight)
- Thread starter heybud
- Start date
- Status
pierre
Senior Member
- Location
- Westchester County, New York
Re: UL listed emt fitting for a wet location (watertight)
Bridgeport has listed fittings in the 1/2, 3/4, and 1 inch size available. Larger sizes are soon to follow.
Pierre
Bridgeport has listed fittings in the 1/2, 3/4, and 1 inch size available. Larger sizes are soon to follow.
Pierre
- Location
- Illinois
- Occupation
- retired electrician
Re: UL listed emt fitting for a wet location (watertight)
I'm going to ask the same question that I have asked every time that this subject has come up. Are threaded couplings for rigid conduit required to be listed as raintight? In my opinion the threaded rigid coupling is much less "raintight" than the standard compression coupling for EMT.
Don
I'm going to ask the same question that I have asked every time that this subject has come up. Are threaded couplings for rigid conduit required to be listed as raintight? In my opinion the threaded rigid coupling is much less "raintight" than the standard compression coupling for EMT.
Don
hurk27
Senior Member
- Location
- Portage, Indiana NEC: 2008
Re: UL listed emt fitting for a wet location (watertight)
Here is some info off UL's web site that might help:
Here is some info off UL's web site that might help:
pierre
Senior Member
- Location
- Westchester County, New York
Re: UL listed emt fitting for a wet location (watertight)
Hello Don
If the coupling for IMC or RMC is made up 'wrenchtight', will it not be raintight? I do not know the answer, I am asking because I always thought it would be raintight. Do you have ifo for this or access to a website for this info?
Somewhere in the deep recess of my mind (okay the small recess of my mind) I remember something about 5 threads .....
Pierre
Hello Don
If the coupling for IMC or RMC is made up 'wrenchtight', will it not be raintight? I do not know the answer, I am asking because I always thought it would be raintight. Do you have ifo for this or access to a website for this info?
Somewhere in the deep recess of my mind (okay the small recess of my mind) I remember something about 5 threads .....
Pierre
- Location
- Illinois
- Occupation
- retired electrician
Re: UL listed emt fitting for a wet location (watertight)
Pierre,
Even when "wrench tight" threaded conduit couplings do not provide a raintight seal. This is because conduit couplings have straight thread and do not provide tight seal between the male and female threads. Plumbing couplings have tapered threads, so that when you install water pipe the taper of the male threads and the taper on the female threads provides a watertight seal. It is my opinion that the standard EMT compression connector (the old type) provides a more "rain tight" connection than does a threaded coupling.
Don
Pierre,
Even when "wrench tight" threaded conduit couplings do not provide a raintight seal. This is because conduit couplings have straight thread and do not provide tight seal between the male and female threads. Plumbing couplings have tapered threads, so that when you install water pipe the taper of the male threads and the taper on the female threads provides a watertight seal. It is my opinion that the standard EMT compression connector (the old type) provides a more "rain tight" connection than does a threaded coupling.
Don
- Location
- Illinois
- Occupation
- retired electrician
Re: UL listed emt fitting for a wet location (watertight)
Tony,
The main purpose of pipe dope on plumbing pipe is to provide lubrication so that the fitting can be tightened enough to force good metal to metal contact between the male and female threads. It should be the tight metal to metal contact between the threads that makes the seal, but pipe dope or tape does help the seal by filling small inperfections in the threads.
Don
Tony,
The main purpose of pipe dope on plumbing pipe is to provide lubrication so that the fitting can be tightened enough to force good metal to metal contact between the male and female threads. It should be the tight metal to metal contact between the threads that makes the seal, but pipe dope or tape does help the seal by filling small inperfections in the threads.
Don
marissa2
Senior Member
- Location
- Connecticut
Re: UL listed emt fitting for a wet location (watertight)
The code states that all conduits threaded in the field must be done with a 3/4-inch per foot taper.
Why is that the couplings are not required to be tapered when made at the factory.
Lou
The code states that all conduits threaded in the field must be done with a 3/4-inch per foot taper.
Why is that the couplings are not required to be tapered when made at the factory.
Lou
Re: UL listed emt fitting for a wet location (watertight)
Perhaps you could get a machinery handbook and look at the sections explaining american pipe threads.
To summarize why the coupling would be staight thread and the pipe tapered 3/4" per ft . I would "Guess" that the joints are being used as a free or loose mechanical connection and not required to be pressure tight such as a NPT connection.
So this is "As I would guess" but when you get the exact answer please post .
Perhaps you could get a machinery handbook and look at the sections explaining american pipe threads.
To summarize why the coupling would be staight thread and the pipe tapered 3/4" per ft . I would "Guess" that the joints are being used as a free or loose mechanical connection and not required to be pressure tight such as a NPT connection.
So this is "As I would guess" but when you get the exact answer please post .
- Location
- Illinois
- Occupation
- retired electrician
Re: UL listed emt fitting for a wet location (watertight)
My guess is that conduit couplings are straight thread only because they are much cheaper to manufacture than a tapered thread coupling. In my opinion the grounding continuity of the conduit system would be greatly improved if we used tapered thread couplings. This is only my opinion and the conduit industry presented a study to the Canadian Code people a number of years ago showing that straight thread couplings are better for grounding. This study was done in support of the conduit industry proposal to eliminate the requirement for tapered thread conduit couplings that was in the Canadian Code at that time. I've never read the study, but don't see how the straight thread coupling could be a better grounding path than a tapered thread coupling. I submitted a proposal to require tapered thread conduit couplings in wet locations a number of years ago, but it was rejected.
Don
My guess is that conduit couplings are straight thread only because they are much cheaper to manufacture than a tapered thread coupling. In my opinion the grounding continuity of the conduit system would be greatly improved if we used tapered thread couplings. This is only my opinion and the conduit industry presented a study to the Canadian Code people a number of years ago showing that straight thread couplings are better for grounding. This study was done in support of the conduit industry proposal to eliminate the requirement for tapered thread conduit couplings that was in the Canadian Code at that time. I've never read the study, but don't see how the straight thread coupling could be a better grounding path than a tapered thread coupling. I submitted a proposal to require tapered thread conduit couplings in wet locations a number of years ago, but it was rejected.
Don
redewire
Member
- Location
- North Dakota
Re: UL listed emt fitting for a wet location (watertight)
I am an electrical coordinator for a major manufacturer with plants in the 48 states and some 37 countries abroad. We have taken the position not to use EMT in any outdoor installation, not only because of the raintight issue, but we find that EMT installed outdoors deteriorates fairly rapidly, especially on the underside of horizontal installations. The difference in cost from EMT and Rigid is not worth the sacrifice. Give me rigid and I will have a installation that will last a long long time.
I am an electrical coordinator for a major manufacturer with plants in the 48 states and some 37 countries abroad. We have taken the position not to use EMT in any outdoor installation, not only because of the raintight issue, but we find that EMT installed outdoors deteriorates fairly rapidly, especially on the underside of horizontal installations. The difference in cost from EMT and Rigid is not worth the sacrifice. Give me rigid and I will have a installation that will last a long long time.
- Status