NM cable on a rooftop

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Why use the angle iron? Is there a minimum acceptable thickness for the angle iron? could you make an angle out of aluminum flashing? Aluminum foil? How about a minimum thickness of the insulation and tar or whatever over the top? Would duct tape be sufficient? Would painting NM be sufficient to make it a dry location?

I don't know what's wrong with it, maybe nothing, but it sure seems like a crappy job, that is probably more expensive than rigid and individual conductors.
 
WorkSafe said:
What would the difference be between a exterior wall with NM and this roof?
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As much as I dislike the install, I think Worksafe has the answer. One thing I did see that I would want addressed is the NM against the sharp corner of the iron.
 
jusme123 said:
no, its an outdoor location
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when it is roofed over it is no longer an outdoor location anymore than it is an outdoor location when it is in an exterior wall.

they are using the angle to create a concealed and protected chase which is perfectly acceptable.

there might be issues of the ambient temperature.
 
dana1028 said:
What about condensation? I know under the roofing material this certainly should be dry. However, the heated cables [winter time] would be expected to create condensation within the raceway [tube channel]....wouldn't it?

We [forum] constantly speak of condensation being the 'wet' issue of conductors in raceways.
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First you don't have a "raceway" that has opposite ends in different temperatures, that alone will reduce the potential amount of condensation pretty drastically. When we have condensation in a raceway it is usually because of warm moist interior air mixing with cold outside air, the cooler air can not hold as much moisture and condensation occurs. A pipe with warm moist air inside and cold walls of the pipe is another common cause. This install has neither condition and there should be very minimal condensation if any. If designed where air can flow pretty freely through the "chase" then you could have condensation issues.

realolman said:
Why use the angle iron? Is there a minimum acceptable thickness for the angle iron? could you make an angle out of aluminum flashing? Aluminum foil? How about a minimum thickness of the insulation and tar or whatever over the top? Would duct tape be sufficient? Would painting NM be sufficient to make it a dry location?

I don't know what's wrong with it, maybe nothing, but it sure seems like a crappy job, that is probably more expensive than rigid and individual conductors.
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Angle iron is likely intended for nail/screw penetration protection, aluminum would not do a very good job of providing this protection. I think we have made it clear this is not a wet location - when it is all finished anyway.
 
We just use uf cable and protect it with steel strips over top of it. Very common way to deal with exposed tongue and groove lumber ceilings that have fans or light fixtures out in the middle of the ceilings. Only time it becomes an issue is when incompetent roofers or carpenters are called in to add a skylight to the roof 20 years later. (a quality volt tick will pick up the signal if they were patient enough to call in a qualified electrician to check for this prior to making the cuts. I have trained at least two builders to do it after expensive repairs ...)
 
kwired said:
I think we have made it clear this is not a wet location - when it is all finished anyway.
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How about "we" making the answers to these questions clear:

does a coat of paint make it a dry location? One coat of tar? Two coats of tar?

how much tar and insulation makes it a dry location?

I just think it is all a bunch of rationalization of a crappy installation that is apparently not specifically prohibited by the NEC.
 
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realolman said:
How about "we" making the answers to these questions clear:

does a coat of paint make it a dry location? One coat of tar? Two coats of tar?

how much tar and insulation makes it a dry location?

I just think it is all a bunch of rationalization of a crappy installation that is apparently not specifically prohibited by the NEC.
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If it is encapsulated why is it not a dry location?

A coat of paint - maybe not a thick enough or durable enough encapsulation to consider it being dry. If you poured concrete over the installation would you still call it a wet location? I think inside of concrete on grade would be considered a wet or damp location but not necessarily for a rooftop.
 
kwired said:
If it is encapsulated why is it not a dry location?

A coat of paint - maybe not a thick enough or durable enough encapsulation to consider it being dry. If you poured concrete over the installation would you still call it a wet location? I think inside of concrete on grade would be considered a wet or damp location but not necessarily for a rooftop.
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NM is not permitted to be installed embedded in concrete, adobe, or masonry unless it is NMC. I still think you are avoiding my point... which is that the installer wanted to do it this way, so he is rationalizing that it is a dry location. If the installer wanted to do it under a coat of paint could not the same justification be used?

Where does it say how much paint, tar, or whatever makes it a dry location?

I simply think it is a poor way to install NM, but apparently there is nothing in the NEC prohibiting it.... so have at it. What if the inpector told you the angle iron had to be 3/16" thick? Where is the minimum required thickness for angle iron chases for NM embedded in roof coating located?
 
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realolman said:
NM is not permitted to be installed embedded in concrete, adobe, or masonry unless it is NMC. I still think you are avoiding my point... which is that the installer wanted to do it this way, so he is rationalizing that it is a dry location. If the installer wanted to do it under a coat of paint could not the same justification be used?

Where does it say how much paint, tar, or whatever makes it a dry location?

I simply think it is a poor way to install NM, but apparently there is nothing in the NEC prohibiting it.... so have at it. What if the inpector told you the angle iron had to be 3/16" thick? Where is the minimum required thickness for angle iron chases for NM embedded in roof coating located?
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But he did not embed it in the roofing material, he installed it in a chase made from the angle iron.

Just because you don't like how it looks doesn't mean it is unacceptable code wise.
 
kwired said:
But he did not embed it in the roofing material, he installed it in a chase made from the angle iron.

Just because you don't like how it looks doesn't mean it is unacceptable code wise.
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True.

and you never answered how thick the angle iron needs to be. Does it even need to be there? or if the chase can't be made of wood or aluminum foil, or tar paper... or a garden hose or duct tape. Who says it needs to protect the NM from nails.. Or how many coats of paint or tar it takes to be a dry location.

If you're going to answer those things with NEC references, I'll be looking forward to it...

I'm done.
 
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realolman said:
True.

and you never answered how thick the angle iron needs to be. Does it even need to be there? or if the chase can't be made of wood or aluminum foil, or tar paper... or a garden hose or duct tape. Who says it needs to protect the NM from nails.. Or how many coats of paint or tar it takes to be a dry location.

If you're going to answer those things with NEC references, I'll be looking forward to it...

I'm done.
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I don't see why this chase couldn't be made from wood or garden hose, or duct tape. Protecting from nails maybe is not done because of code but just as a design choice, just like choosing to run NM in the first place is a design choice. Do you have any NEC reason not to run NM cable in this installation that falls within parameters of what we know so far about the installation? Like assuming this is not a location where NM cable is prohibited by reasons other than the roof construction details.
 
kwired said:
No they are both simply concealed within the roof or walls. Thread title is somewhat misleading here, should maybe be titled "NM cable in a roof" as that is what finished product will be.
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petersonra said:
when it is roofed over it is no longer an outdoor location anymore than it is an outdoor location when it is in an exterior wall.

I disagree, your penetrating the metal roof decking
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realolman said:
True.

and you never answered how thick the angle iron needs to be. Does it even need to be there? or if the chase can't be made of wood or aluminum foil, or tar paper... or a garden hose or duct tape. Who says it needs to protect the NM from nails.. Or how many coats of paint or tar it takes to be a dry location.

If you're going to answer those things with NEC references, I'll be looking forward to it...

I'm done.
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300.4(F)
1.6mm (1/16")
 
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kwired said:
jusme123 said:
Where? Entire run is under the final roof decking from what I understand.
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I think we need further explanation from dana1028 the original poster. OK if the roof is not penetrated, I still can't imagine a

roof top panel as the source for these 12 AWG romex's. As for the load end of these wires flood lights come to mind. Conduit would have

been a better choice IMO. I think it is a tacky installation.
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