water tight couplings
- Thread starter Ponchik
- Start date
- Status
Bang
Member
- Location
- Northern Virginia
My question for you is this:
What if you have a conduit entering dead center on the top of a panel from a roof penetration. Let's say the sealing compund gave way and now you have water leaking through and did NOT have rain-tight fittings.....would this save the main busbar?
What if you have a conduit entering dead center on the top of a panel from a roof penetration. Let's say the sealing compund gave way and now you have water leaking through and did NOT have rain-tight fittings.....would this save the main busbar?
What if the rain tight fitting gave away?
- Location
- Logan, Utah
What is the purpose of the rain tight EMT couplings/connectors when the conductor inside is wet location rated?It doesn't make sense.
When the CMP approved this did they question it a bit?
Why doesn't it make sense to minimize the intrusion of water into a raceway system?
Chris
It makes sense to try and stop water intrusion, But what doesn't make sense is EMT on the wall with intrusion power couplings and it transitions into PVC underground where the PVC is not water tight and we all know it will get filled with water in no time.
Or EMT on the wall an dit transitions into thread less IMC coupling. is that water tight?
- Location
- Logan, Utah
The reason that water collects in PVC is condensation from air in the raceway not from water entering from the ground. If you take and use primer and PVC glue on all the joints you will still have water in the raceway due to condensation.
Chris
Chris
- Location
- Illinois
- Occupation
- retired electrician
If that is an issue why are we permitted to use straight threaded conduit couplings? Rigid couplings leak a lot more than the old compression type EMT couplings.
dhalleron
Senior Member
- Location
- Louisville, KY
- Occupation
- Master Electrician/Senior Fire Alarm Technician
I must have sucked 5 gallons of condensation out of some pipes with my shop vac while trying to pull in a mouse and string.
230.53
- Location
- Massachusetts
I don't see anyone trying to explain it.
I agree with Don, it does not make a bit of sense.
- Location
- New Jersey
- Occupation
- Journeyman Electrician
The wet location standard was added by a proposal from NEMA with the intent to do nothing more than align EMT fittings used in wet location with the requirements in Article 314.
- Location
- Massachusetts
Rob, I am not following you here.
It was my understanding we were talking about the UL listing change that made all the EMT compression fittings we have used in the past as no good and now when ordering compression fittings you have to ask for the new wet location type.
- Location
- New Jersey
- Occupation
- Journeyman Electrician
That's possible and could have been the resaon for the proposal. Or it could have been the other way around, the NEC changed the requirment and then the listing agency followed the new code wording.
- Location
- Massachusetts
I belive UL pulled the the listing first, either way it makes no sense.
The old compression fittings were 'raintight' for decades and all of a sudden UL said no they are not, you need a new more expensive type of raintight fitting. All the while ignoring threaded conduit couplings are not raintight.
- Location
- Illinois
- Occupation
- retired electrician
That does not address my question. Why is water intrusion only an issue with. EMT? If water tight couplings are really necessary why does NEMA Cal for the use of tapered threads for rigid conduit couplings. The now used straight thread couplings leak more than the EMT couplings that were used in the past.
- Location
- New Jersey
- Occupation
- Journeyman Electrician
Actually I was addressing the OP which asked about a comment from the CMP. I, like you, have no idea why we needed this change in the code wording.
kwired
Electron manager
- Location
- NE Nebraska
- Occupation
- EC
Probably whoever makes couplings - I could see the current straight thread couplings being easier to make, tapered threads will require a little more to get it done, but they can still charge a lot more for tapered couplings and sell them to the people that are using them outdoors, just like we still have the old EMT fittings available, they just have more limitation to where they can now be used.
kwired
Electron manager
- Location
- NE Nebraska
- Occupation
- EC
I really dislike the fact that most Mfgr's put a center hub into most 3R panels. Even if you have raintight fittings, and seal everything imaginable, you still get condensation inside the raceway, and it runs right into the main breaker, or onto the bus.
The southwest parts of the country have less of this problem, but it still does happen some.
Any place that experiences high humidity frequently, has this problem almost daily.
kwired
Electron manager
- Location
- NE Nebraska
- Occupation
- EC
I one time remember burying a PVC raceway on a Friday on a hot humid summer day. Come back Monday to pull conductors, raceway was not full of water but there was enough moisture in there that the pulling rope pulled out damp. It did not rain over that weekend either, it was just warm moist air that condensed when it entered the cool underground environment. If you get that much in just a couple days it will not take very long to fill it.
Consider that a well sealed raceway will contain this water that actually condensed from within and it will fill up until no more air can flow through the raceway. Then the amount of warm humid air entering will be reduced and less condensation will occur. A raceway that is not well sealed will actually drain this water accumulation.
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