Rough in before Dry in

[Seven-Delta-FortyOne]

I think the bigger issue than whether Romex can get mist on it is, if you’re roughing in before dry-in, there’s a bunch of other issues:

-Are HVAC and plumbing done as well? Because we generally come after those guys.

-Siding nails and nails used for sheathing and shear walls are usually a lot longer than a drywall screw for 1/2” rock. Chances of (many) nails penetrating your wiring goes way up.

-Chances of having something damaged when major framing is still going on, goes up.

-There is probably a ton of blocking that still need to be installed, and the possibility of your wiring being in the way of at least some of it is close to 100%.

Just a couple things to keep in mind.

 

[mtnelect]

On most large construction projects, they have a "Resolution Committee" that meets monthly, to resolve conflicts among the trades. On smaller projects, they have to fight among themselves.

 

[Choice_Gorilla]

I think the bigger issue than whether Romex can get mist on it is, if you’re roughing in before dry-in, there’s a bunch of other issues:

-Are HVAC and plumbing done as well? Because we generally come after those guys.

-Siding nails and nails used for sheathing and shear walls are usually a lot longer than a drywall screw for 1/2” rock. Chances of (many) nails penetrating your wiring goes way up.

-Chances of having something damaged when major framing is still going on, goes up.

-There is probably a ton of blocking that still need to be installed, and the possibility of your wiring being in the way of at least some of it is close to 100%.

Just a couple things to keep in mind.

Or some scumbag coming in and cutting out all of the copper.

 

[roger]

As Rob mentions in post #15, on large projects you can not risk falling behind especially if there are $1,000 or more per day Liquidated Damages. You start as soon as you can. We would mobilize and start installing early in the project as did most other subs.

 

[Strathead]

I think the bigger issue than whether Romex can get mist on it is, if you’re roughing in before dry-in, there’s a bunch of other issues:

Why do you consider this a bigger issue? My belief is the issue with Romex and water is the water wicking up the paper and staying there. Over time mold developing. The wire insulation itself is THWN and it is no big deal for it to be surrounded by water. So, it isn't really an electrical issue. I am not trivializing the problem with water wicking inside, but MIST on the cable jacket? I am curious, how many of you have always thrown out MC or Romex that was rained on prior to getting it under cover? I will take the 5th on that question myself.

 

[infinity]

Why do you consider this a bigger issue? My belief is the issue with Romex and water is the water wicking up the paper and staying there. Over time mold developing. The wire insulation itself is THWN and it is no big deal for it to be surrounded by water. So, it isn't really an electrical issue. I am not trivializing the problem with water wicking inside, but MIST on the cable jacket? I am curious, how many of you have always thrown out MC or Romex that was rained on prior to getting it under cover? I will take the 5th on that question myself.

I've seen NM cable run in raceways outdoors that had been there for 20 years without an issue. The thought that some rain or water hitting the cable during construction is going to permanently damage it seems far fetched to me.

 

[Fred B]

Why do you consider this a bigger issue? My belief is the issue with Romex and water is the water wicking up the paper and staying there. Over time mold developing. The wire insulation itself is THWN and it is no big deal for it to be surrounded by water. So, it isn't really an electrical issue. I am not trivializing the problem with water wicking inside, but MIST on the cable jacket? I am curious, how many of you have always thrown out MC or Romex that was rained on prior to getting it under cover? I will take the 5th on that question myself.

Wet paper inside, the jacket will hold onto the moisture and not dry out. the wet paper will compromise the heat dissipation capability of the NM cable.

 

[don_resqcapt19]

Wet paper inside, the jacket will hold onto the moisture and not dry out. the wet paper will compromise the heat dissipation capability of the NM cable.

How would it do that? The wet paper will be more thermally conductive than the dry paper.

 

[don_resqcapt19]

I've seen NM cable run in raceways outdoors that had been there for 20 years without an issue. The thought that some rain or water hitting the cable during construction is going to permanently damage it seems far fetched to me.

Even directly buried, I have seen it last that long.

 

[LarryFine]

How would it do that? The wet paper will be more thermally conductive than the dry paper.

Conductor wet ratings have always been lower than dry (when not the same), not higher.

 

[don_resqcapt19]

Conductor wet ratings have always been lower than dry (when not the same), not higher.

That has nothing to do with the statement that said "the wet paper will compromise the heat dissipation capability of the NM cable".

I don't understand how the wet paper could be less thermally conductive than dry paper.

 

[LarryFine]

That has nothing to do with the statement that said "the wet paper will compromise the heat dissipation capability of the NM cable".

Then why does water in conduit compromise heat dissipation?

 

[don_resqcapt19]

Then why does water in conduit compromise heat dissipation?

It doesn't. No idea of what the dry and wet temperature ratings are based on, but wet material and water is always more thermally conductive than air. I expect it has something to do with the thermoplastic insulation material and not the actual heat dissipation.

 

[wwhitney]

Then why does water in conduit compromise heat dissipation?

Do you have any evidence that it does, beyond the temperature ratings of say, THWN, where the wet rating (75C) is lower than the dry rating (90C)?

Because that could be due to other reasons. For example, maybe the plastic more easily thermally degrades in the presence of water.

Cheers, Wayne

 

[Ohm2]

How would it do that? The wet paper will be more thermally conductive than the dry paper.

The paper insulation in NM cable helps in heat dissipation by providing a certain amount of air space. When this insulation becomes wet, its ability to dissipate heat effectively is compromised. The moisture can also cause additional heat buildup due to increased electrical resistance and reduced dielectric strength.

 

[Ohm2]

Do you have any evidence that it does, beyond the temperature ratings of say, THWN, where the wet rating (75C) is lower than the dry rating (90C)?

Because that could be due to other reasons. For example, maybe the plastic more easily thermally degrades in the presence of water.

Cheers, Wayne

Two words: thermal conductivity

 

[jaggedben]

Depends on your AHJ. When I was wiring houses, an inspector stopped by because he was "in the neighborhood" while I was working. It was raining heavily and the roof was dried-in but the house had no windows installed. He told me that he wouldn't pass a rough-in unless I removed a lot of the NM cable near window openings. I've had others that it didn't bother them one bit if the structure wasn't 100% dry. If you have to get in now for scheduling purposes, talk to your inspector and go by what he says.

What a jerk.

 

[jim dungar]

Two words: thermal conductivity

Two better words: heat transfer.

Moving air might remove heat faster than stagnant water.

 

[Ohm2]

Two better words: heat transfer.

Moving air might remove heat faster than stagnant water.

Exactly

 

[wwhitney]

Two words: thermal conductivity

Sure, but your assumption that dry paper plus air is more thermally conductive than wet paper plus water is unsupported. My guess is it would be the opposite, but without any data, we are just guessing.

Cheers, Wayne