what do you think?

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Ponchik

Ponchik

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Location
CA
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Electronologist
NM cable going across a sheet metal heating duct. After the heater being ON for 10 minutes I had my hand on it for 2 minutes and it was warm not hot. So I am assuming the NM cable wrapped with heat tape should be OK the way it is installed.

What do you think?

Thanks.

20130219_131802.jpg
 
Little Bill

Little Bill

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Location
Tennessee NEC:2017
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Semi-Retired Electrician
jumper said:
I am really tired, but am I seeing or not seeing a problem with 334.30(A) here with the cables into the box and such?
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Not really much different than fishing in finished walls.

But I suppose one could add a staple to the 2x4 the box is mounted to.
The 2x4s that has the nail plates would be the support though.

Edit to add: There could be a staple behind the nail plates and it looks like it is within 12" of the box.
 
J

jap

Senior Member
Occupation
Electrician
I'd sleeve it.

Although it may not be needed, I'd feel better that I tried to do something to improve on this situation.
 
J

jap

Senior Member
Occupation
Electrician
ActionDave said:
It looks like the guy tried to do just that. If he had sleeved it what would you do? Pour concrete around it?
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He did'nt sleeve it. He put up nail plates and wrapped high heat tape around the 3 romexes.

I would have put an emt raceway between the studs and ran the romexes through it in that area.
 
Ponchik

Ponchik

Senior Member
Location
CA
Occupation
Electronologist
jap said:
He did'nt sleeve it. He put up nail plates and wrapped high heat tape around the 3 romexes.

I would have put an emt raceway between the studs and ran the romexes through it in that area.
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The EMT would not have worked. The duct is 3.5" so it was taking up most of the bay so there is no room for EMT. My concern is/was the heat not physical protection.
 
J

John120/240

Senior Member
Location
Olathe, Kansas
edward said:
The EMT would not have worked. The duct is 3.5" so it was taking up most of the bay so there is no room for EMT. My concern is/was the heat not physical protection.
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You will be just fine. The duct pictured moves air, hot or cold from here to there. The surface temperature of the duct should not be greater than the air inside.
 
J

jap

Senior Member
Occupation
Electrician
If theres room for 3 Romexes taped together, then you'd think there'd be room for chases, even if there had to be 3 of them.

With the romexes jammed between the sheetrock and the vibrating duct work, My concern would be the Physical Protection not the heat, which was said was not enough to worry about anyway.
 
J

jap

Senior Member
Occupation
Electrician
Looks like your going to gain another 1/2" anyway for another layer of sheetrock, or was the Nailon box fastened to the face of the existing sheetrock for the heck of it?
 
J

jap

Senior Member
Occupation
Electrician
I thought the reason for Nail plates was since the romex passed through a bored hole, the back of the hole provided a solid backing that a screw could penetrate the cable.(No different than the metal backing of the duct in the picture behind the romex).

On a block wall where the cable could be installed in a shallow groove, a metal covering of at least 1/16" must be installed over the entire cable to protect it.We dont have to install nail plates between the studs of the cable is running horizontally since the cable is less likely to be penetrated by a nail, since it is to be installed at least 1 1/4" back from the face of the stud and has some flexibility to get out of the way.

The OP indicated that the duct was 3.5" thick which tells me the romex is more or less running on face of the studs covered by no more than whatever covering is going to go over the existing sheetrock,not concealed inside the wall as it should be.

To me this install fails in several aspects.

Heat from the duct would be the least of my worries.The possibility of physical damage would be my main concern.

JAP>
 
J

jap

Senior Member
Occupation
Electrician
We're probably looking at something other than the bottom floor since theres no bottom plate.
 
al hildenbrand

al hildenbrand

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Location
Minnesota
Occupation
Electrical Contractor, Electrical Consultant, Electrical Engineer
jap said:
I thought the reason for Nail plates was since the romex passed through a bored hole, the back of the hole provided a solid backing that a screw could penetrate the cable.(No different than the metal backing of the duct in the picture behind the romex).
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I submit the reason is simply the language of 300.4.

And the 2011 NEC 300.4 language does not talk about how "the metal backing of the duct" is like a framing member.
jap said:
To me this install fails in several aspects.

Heat from the duct would be the least of my worries.The possibility of physical damage would be my main concern.
Click to expand...
The only shallow groove that exists in this install is in the wood studs which invokes 2011 NEC 300.4(A)(2), and if one of those visible 2x4s is a cripple (not a "member") then that 2x4 is not required to have a nail plate.

The metal duct is not a metal framing member, so none of 300.4(B) applies.

The metal duct does not have a shallow groove in it so 300.4(F) does not apply.

"I think" the install pictured in the OP is compliant with the NEC.
 
J

jap

Senior Member
Occupation
Electrician
al hildenbrand said:
I submit the reason is simply the language of 300.4.

And the 2011 NEC 300.4 language does not talk about how "the metal backing of the duct" is like a framing member.
The only shallow groove that exists in this install is in the wood studs which invokes 2011 NEC 300.4(A)(2), and if one of those visible 2x4s is a cripple (not a "member") then that 2x4 is not required to have a nail plate.

The metal duct is not a metal framing member, so none of 300.4(B) applies.

The metal duct does not have a shallow groove in it so 300.4(F) does not apply.

"I think" the install pictured in the OP is compliant with the NEC.
Click to expand...

I can appreciate all of this but in my mind, a 2x4 Cripple is just as solid as a 2x4 member,the metal duct is not a framing member,but its a pretty solid member in itself,it also doesnt have a shallow groove in it which makes the romex butt up against the back of the tile or whatever is going to be put on top of the sheetrock which is what bothers me the most,I also believe by the rules the installed picture is compliant with the NEC but if it were my job, I'd never do this, I'd have go a bit further to be able to sleep at night, but thats just what I think and that's what the OP asked for to begin with.

JAP>
 
Ponchik

Ponchik

Senior Member
Location
CA
Occupation
Electronologist
jap said:
Looks like your going to gain another 1/2" anyway for another layer of sheetrock, or was the Nailon box fastened to the face of the existing sheetrock for the heck of it?
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I am not gaining anything the removed sheetrocked will be replaced and there is 1/4" tiled back splash being installed.

John120/240 said:
I think we are looking at the floor. My question is how will the base molding fit in this situation ? I guess molding could stop short of the two gang box.
Click to expand...

This is kitchen counter top.

jap said:
I thought the reason for Nail plates was since the romex passed through a bored hole, the back of the hole provided a solid backing that a screw could penetrate the cable.(No different than the metal backing of the duct in the picture behind the romex).

On a block wall where the cable could be installed in a shallow groove, a metal covering of at least 1/16" must be installed over the entire cable to protect it.We dont have to install nail plates between the studs of the cable is running horizontally since the cable is less likely to be penetrated by a nail, since it is to be installed at least 1 1/4" back from the face of the stud and has some flexibility to get out of the way. The nail plate is required only when the NM cable is going through the stud and is within 1.25" of the face of the stud at which point it is installed to protect the cable. I always install protective plates regardless if it cripple wall or ceiling, if my cables go through a hole and the hold is within 2" of the face of the stud it gets a nail plate.

To me this install fails in several aspects. Why does it fail inspection? JAP>
Click to expand...

The boxes are about 1.5" above the counter top.
 
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