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Dry or damp?

ICE said:
Since when is an informational note code text.

The damp area described in the informational note is the space under the porch ceiling. It has nothing to do with the enclosed area above the ceiling. Beyond that, informational notes are there for edification purposes only. Suggestions as it were. You can like them and ignore them with aplomb.
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The informational notes are for guidance and help the AHJ interpret the intention of the code, which they are allowed to do. If I were in Southern California, I might have a different interpretation than I would in the Southeast US or the Northeast.
 
wwhitney said:
If your porch has a ceiling, the area above it is fully protected,
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Most of the time, they are all vented soffits because it is almost impossible to properly ventilate that space. This is why the information note comes in handy, because geographic location has a significant bearing on this. As someone who had to work on wiring and fixtures in these areas, I see firsthand the deterioration of the wires. This is why the AHJ is allowed to make the call. It is because we have practical experience in our regions and realize the code is not a book that you have to be completely literal. It is a combination of academics and practical experience.
 
jar546 said:
As someone who had to work on wiring and fixtures in these areas, I see firsthand the deterioration of the wires.
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Would be interested to see photos of what you mean, if you have any.

Also, it occurs to me that coastal salt air may be more corrosive than typical humidity, and so may be contributing to some of the deterioration. Not sure if that counts as "damp," but is certainly something that should be considered in wiring and fixture selection.

Cheers, Wayne
 
wwhitney said:
Would be interested to see photos of what you mean, if you have any.

Also, it occurs to me that coastal salt air may be more corrosive than typical humidity, and so may be contributing to some of the deterioration. Not sure if that counts as "damp," but is certainly something that should be considered in wiring and fixture selection.

Cheers, Wayne
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I have limited experience as an electrician in South Florida near the coast, only about 7 months' worth, and it was eye-opening. I have not been working in the northeast for over 13 years and don't have specific photos, but I can provide you with details. First, you often can't tell the difference between the black and white wire in NM cable that has been through a lot of humidity and heat cycles outside, as they both appear to be black, although the white ends up more of a dark brown/black color and you have to strip back the outer jacket of the NM cable to see the color if there is enough slack to do so. Next is the actual NM jacket itself, which starts to turn color and darken. The insulation on the wires gets brittle as they discolor. Older NM cable is even worse because the cloth-style jacket and insulation often fall apart just by touching it. Attics and roof overhangs are the worst, basements after that, depending on how humid they get, and inside the walls are usually in pretty good shape. The same goes for older BX/AC cable. The insulation on the wires becomes brittle and is difficult to work with. You usually end up having to replace entire runs, or stripping it back and adding a junction box.
 
jar546 said:
If I were in Southern California, I might have a different interpretation than I would in the Southeast US or the Northeast.
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The climate makes a difference. It never rains in Southern California. We even wrote songs celebrating that. Having lived in Daytona Beach, I understand why every location in Florida is wet, or on a good day, damp.
 
This is not exactly what you are looking for, but here is an example of what we find in an attic. I am only showing this for one reason. There is an older piece of NM cable that has darkened so much it is a darkish brown, and the insulation was very brittle as I recall. There was no junction box at all in this disaster.

ElecNoJuncBox.jpg
 
ICE said:
The climate makes a difference. It never rains in Southern California. We even wrote songs celebrating that. Having lived in Daytona Beach, I understand why every location in Florida is wet, or on a good day, damp.
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Daytona Beach is about 3.5 hours north of me. When I visit there, the locals say it hasn't been the same since you left.
 
Well, I thought a fairly simple Q and A through post 3.

Brought up another issue. Does IRC require venting on porch roofs? (Related, does IRC require ice and water shield on porch roofs?)

I'll just offer my observation that the porch I'm working on and adding onto was built in 1994. Looking at it's "attic" after removing vinyl soffit ceiling (replacing with pine edge and center bead) I was impressed by how pristine the underside of the ceiling and the framing was. Yes, dust on horizontal surfaces, but otherwise like new. It does not seem like a very hostile to electrical work environment.

On code annexs, appedicies, and commentaries, they are someone's - often staff - opinions, and not those of the experts and others who actually are responsible for the code text. I urge caution in relying on them.
 
wwhitney said:
Would be interested to see photos of what you mean, if you have any.

Also, it occurs to me that coastal salt air may be more corrosive than typical humidity, and so may be contributing to some of the deterioration. Not sure if that counts as "damp," but is certainly something that should be considered in wiring and fixture selection.

Cheers, Wayne
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I have also experienced the degradation in this scenario, which is why my first post was damp.
 
Gregg Harris said:
I have also experienced the degradation in this scenario, which is why my first post was damp.
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OK, but what evidence do we have that the degradation is moisture related, as opposed to just age or heat related? Finding 50+ year old degraded wiring is not so unusual, everything has a life span.

My current thinking on this matter is that a building generally has 4 control layers: bulk water, air, water vapor, and thermal. And that only the bulk water control layer matters for determining whether a location is dry, damp, or wet due to weather. [A porous leaky basement wall could cause damp conditions due to ground water, and wash down activities could cause a damp or wet location inside a building.]

Also, on this question of condensation, it is certainly conceivable that a ventilated, unconditioned space could end up below the dew point of outside air, so that humid air entering the space will lead to condensation. But what I'm not clear on what combination of normal weather conditions and normal building practices would lead to this occurring to sufficient degree to yield a damp location. ["A location classified as dry may be temporarily subject to dampness or wetness,"]

For new construction, concerns like this help tilt the balance towards sealed attics and sealed crawl spaces, at least for me.

Thanks, Wayne
 
wwhitney said:
OK, but what evidence do we have that the degradation is moisture related, as opposed to just age or heat related? Finding 50+ year old degraded wiring is not so unusual, everything has a life span.

My current thinking on this matter is that a building generally has 4 control layers: bulk water, air, water vapor, and thermal. And that only the bulk water control layer matters for determining whether a location is dry, damp, or wet due to weather. [A porous leaky basement wall could cause damp conditions due to ground water, and wash down activities could cause a damp or wet location inside a building.]

Also, on this question of condensation, it is certainly conceivable that a ventilated, unconditioned space could end up below the dew point of outside air, so that humid air entering the space will lead to condensation. But what I'm not clear on what combination of normal weather conditions and normal building practices would lead to this occurring to sufficient degree to yield a damp location. ["A location classified as dry may be temporarily subject to dampness or wetness,"]

For new construction, concerns like this help tilt the balance towards sealed attics and sealed crawl spaces, at least for me.

Thanks, Wayne
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wire nuts and wires with corrosion on them, not necessarily the covering degradation that you would see with fiber-covered or heat-related brittleness, oxidation on bulb base.
 
wwhitney said:
OK, but what evidence do we have that the degradation is moisture related, as opposed to just age or heat related? Finding 50+ year old degraded wiring is not so unusual, everything has a life span.
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It is called experience. Even new wiring is not holding up in high-moisture environments. I've been in thousands of moisture-laden crawlspaces in the Poconos, and the wiring all has something in common; they are discolored and deteriorated. If the manufacturers believed in NM as much as some might think they do, they would not UF cable and other types of wiring available, and they would have done testing to prove that regular NM can handle damp areas. They have not because it is the cheap stuff. I won't use it in my own house. I pulled a permit to run some receptacles in my garage about 2 years ago and I used EMT and THWN. In my opinion, it is garbage.

First of all, NM cable, also known as 'Romex,' was initially developed as a less expensive wiring method to help keep construction costs down. This is why there are special rules for NM that don't apply to other types of wiring. When we wire commercial structures, we use MC cable, conduit with THWN, or a combination of both. There is a reason for this. NM cable is the lowest grade of wiring allowed by the code. It has its limitations.
 
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