Opinions sought NM inside conduit outside

[iwire]

Wow talk about avoiding direct questions! :grin:
Doesn't matter how many times I ask what questions, your gonna keep on say that no matter how it doesn't jive with other codes.

You want to know what I really think?

I think the code is a mess in this area.

I think they are starting to address it.

I think within the next few code cycles we will see more changes regarding locations and the equipment we can use in those locations.

I think most of us have been installing equipment in areas that we will not be able to in the future without that equipment having a WP listing.

 

[Twoskinsoneman]

You want to know what I really think?

I think the code is a mess in this area.

I think they are starting to address it.

I think within the next few code cycles we will see more changes regarding locations and the equipment we can use in those locations.

I think most of us have been installing equipment in areas that we will not be able to in the future without that equipment having a WP listing.

Yeah I guess that is what I wanted....
Fair enough... If the inside of enclosures in wet/damp areas are wet/damps areas and the inside of conduits in damp areas are also damp areas I hope they make that clear also....

 

[220/221]

Keep in mind that Iwire doesn't WRITE the code so don't kill the messenger.

 

[Twoskinsoneman]

Keep in mind that Iwire doesn't WRITE the code so don't kill the messenger.

Don't tell him that his whole reality may shatter! (Joke)
I don't think iwire's comments about the interior of an enclosure in a damp location being a damp location has any bases in code...


In fact neither does he!! :grin::grin: SEE:

What code sections do you base your answers on?

I base it on how the world works.

 

[iwire]

Keep in mind that Iwire doesn't WRITE the code

Oh sure ........ bust my bubble. :grin:

Don't tell him that his whole reality may shatter! (Joke)

It was shattered :grin:

I don't think iwire's comments about the interior of an enclosure in a damp location being a damp location has any bases in code...


In fact neither does he!! :grin::grin: SEE:

No that is not what I think. For example I do not need a code to tell me the inside of a conduit is the same temp as the surrounding area (other then any conductor temp increases, direct sun etc.)

I also do not need a code to tell me that the inside of a conduit installed in a damp location is also damp.

When the NEC does not define a word I believe we are to use Merriam Webster

Main Entry: damp

Pronunciation: 'damp

Function: noun

Etymology: Middle English, black damp, from Middle Dutch or Middle Low

German, vapor; akin to Old High German damph vapor

1 : a noxious gas -- compare BLACK DAMP, FIREDAMP

2 : MOISTURE: a : HUMIDITY, DAMPNESS b archaic : FOG, MIST

3 a : DISCOURAGEMENT, CHECK b archaic : DEPRESSION, DEJECTION

So if you install a conduit in a location that is "Damp" (AKA Humid, misty, foggy) the interior of that conduit will also be humid unless you have magic conduit that is truly sealed air tight.

The air inside the conduit will exchange with air outside the conduit due to the airs expansion and contraction from temperature swings.

These are facts and do not need the NEC to say they happen. :smile:

 

[Twoskinsoneman]

Oh sure ........ bust my bubble. :grin:




It was shattered :grin:




No that is not what I think. For example I do not need a code to tell me the inside of a conduit is the same temp as the surrounding area (other then any conductor temp increases, direct sun etc.)

I also do not need a code to tell me that the inside of a conduit installed in a damp location is also damp.

When the NEC does not define a word I believe we are to use Merriam Webster



So if you install a conduit in a location that is "Damp" (AKA Humid, misty, foggy) the interior of that conduit will also be humid unless you have magic conduit that is truly sealed air tight.

The air inside the conduit will exchange with air outside the conduit due to the airs expansion and contraction from temperature swings.

These are facts and do not need the NEC to say they happen. :smile:

Well it is only my opinion but I disagree. And 300.9 sets a presedent of sorts. If you are right then 300.9 is unnecessary. Also the word enclosure could have easily been added to 300.9 llike it is in 300.5(B)

Also my house is not air tight but I don't consider the inside subject to whatever is outside. If I was a tiny electron inside a conduit/enclosure looking around, I would feel like a guy standing inside his house. Just because it is raining outside the conduit does not mean it is raining inside. IF the coduit is made-up properly (under normal conditions) the rain will stay outside.

So unless the code says it, (which in the case of wet areas it does) IMO the inside of condiuts, enclosures is not subject to the wet/damp classification of it surroundings.

 

[iwire]

Also my house is not air tight but I don't consider the inside subject to whatever is outside.

I assume your house has a heating / cooling system which conduits do not usually have?

If I leave my AC off during humid weather my home becomes humid.

Is it humid enough to call damp ....... sure sometimes, do I think that an AHJ should prohibit NM in my home because of this ...... No.

If I was a tiny electron inside a conduit/enclosure looking around, I would feel like a guy standing inside his house. Just because it is raining outside the conduit does not mean it is raining inside. IF the conduit is made-up properly (under normal conditions) the rain will stay outside.

Really? RMC couplings are not water tight and the NEC does in fact tell us that it is a wet location.

But I thought we were talking about 'damp'?

So unless the code says it, (which in the case of wet areas it does) IMO the inside of conduits, enclosures is not subject to the wet/damp classification of it surroundings.

So even though many conduits do in fact keep rain out of the conduit and the NEC says it is a wet location inside you still will not accept that a conduit run in a damp location will not be damp inside even though it is a fact that few conduits are sealed air tight?

I think you have dug your heels in and can not see the forest for the trees. :smile:

There is no mechanism in place to keep dampness out of a conduit in damp locations unless you pump dry air into the conduit.

 

[Twoskinsoneman]

I think you have dug your heels in and can not see the forest for the trees. :smile:

That's not really the way I feel. I'm open to consider your opinion...

However you've admitted already that your opinion of the interior of enclosures in wet/damp causes you to violate 110.11...IMO if truly believe that you should stop. So I may consider your viewpoint and see it does have some logic but I'm not convinced.

That's a little different from diggin my heels in and refusing to see reason. Why would we need 300.9 if it so just logically obvious?

BTW I also disagree with your interpretation of "moderate degrees of moisture". IMO humid air is not moderate moisture. I believe the intent is actual moisture... such as possibly mist being blown on the conduit during a rain storm even though it is under a canopy. BUT "moderate" moisture is obviously highly debateable.

 

[itsunclebill]

At what humidity does it become "damp"? NM-B run in an attic is in an area with the same humidity as the outside air. And, if the humidity is close to 100% outside so is the attic air. Any slight reduction of temperature in these conditions causes condensation to form on the cable, making it officially wet (AND damp). I would argue the areas inside closed walls will eventually get to the point that a change in temperature will cause moisture to form if exposed to humid conditions (think a long duration wet weather pattern) and the temperature cools to the dew point. How long can this go on till it is considered a damp/wet location?

All we have here is a colossal screw up in code language and arguably goofy intent. Either ban NM-B outright because it is going to be in damp conditions at least some of the time or get reasonable with restrictions, or get the stuff listed for use in damp locations.

 

[aftershock]

In Memphis, TN NM is run in conduit which is located outside and even in conduit which is run underground.
Here in Bryan, TX NM is also run in conduit located ouside and even in conduit which is run underground.
I dont think I will ever work in an area where the NEC is followed as it is worded.