400.8(5)

[charlie b]

Chapter 300 wiring method supplies a 2x4 metal box with a receptacle outlet, mounted above a suspended ceiling. A manufacturer's "power supply" box is mounted nearby. The power supply has a flexible cord with a cord cap, and is plugged into the adjacent receptacle outlet. So far, an obvious violation of 400.8(5). Now consider having both the receptacle outlet box and the power supply box, as well as the flexible cord that connects the two, all installed within a NEMA 1 enclosure. It is still above a suspended ceiling. Is it still a violation?

This is what the owner's rep told the contractor to do, and now the owner's rep is saying "oops, bad idea, find another solution." I will post a photo shortly.

 

[GoldDigger]

Applying Mike's argument, if the power supply cord is an integral part of it or supplied with it (if detachable), then it is not prohibited in the first place.
Putting it into a NEMA enclosure only improves the situation, IMHO, if you get a UL listing for the resulting assembly.

Tapatalk!

 

[charlie b]

The contractor purchased the enclosure and mounted it on the ceiling. Then they installed the receptacle outlet box and the power supply inside the enclosure. I doubt that it is possible to get a UL listing for the complete assembly.

But I am not familiar with the ?Mike?s argument? to which you refer. The power supply box does come from its manufacturer with a cord. How does that play into 400.8(5)?

Attached is a photo of the enclosure. The large white box is the power supply, but its power cord is not visible in this view. The receptacle outlet box is to the right side of the enclosure, but the receptacle is not yet installed.

 

[GoldDigger]

There are a couple of *long* threads covering the argument that UL listed power supply cords do not constitute "flexible cords" under the NEC definition. I will try to find a link if you have a problem finding one.

Tapatalk!

 

[charlie b]

Thanks. I found one. It led me to the fact that there is a different UL standard for flexible cords (UL 62) and power supply cords (UL 817). I will use that as the basis for giving the contractor my opinion that the installation does not violate 400.8.

 

[GoldDigger]

Glad you found it. One thing that the long discussion brings forward is that neither AHJs nor even the assigned CMP members are of one mind on this question. Both on the intent and the actual code language.


Tapatalk!

 

[charlie b]

For that matter, varous members of this forum are in disagreement. What a notion! Don't think I have seen that happen on any other topic of discussion. :happyno::lol:

 

[Dennis Alwon]

I believe part of the reason that the flexible cord is not allowed above a ceiling is because of the toxic fumes. If the cord is within a raceway and no part of it exposed then I would think you are okay.

Not sure if there are other reasons for not allowing this install. I have heard the NEC wants the cable visible so that it an be inspected from damage - the old rubber cord used to dry out in attics but above a ceiling I doubt it would be an issue. I would get an authority having jurisdiction call on it.

 

[charlie b]

I would get an authority having jurisdiction call on it.

This is one of those rare cases in which that would not help. It is on a US military base, and the AHJ is the US Army Corps of Engineers. It was a COE person who told the contractor to install the enclosure, and then later changed his mind and said some other solution is needed. Since this is a design/build project and I am the designer, my role is to help the builder (i.e., the electrical contractor) find a viable solution. I sent in my opinion (as described above). If the COE doesn't agree, then I might be coming back here for more ideas.

 

[al hildenbrand]

Thanks. I found one. It led me to the fact that there is a different UL standard for flexible cords (UL 62) and power supply cords (UL 817).

For those viewing this thread that missed the thread, it came from a question that Mike Holt asked Ryan Jackson about a year ago. As they kicked about the question, they were stunned at what they found, and Ryan then started a thread for us to participate in.

You can read the thread by clicking on "cords" above ceilings

 

[don_resqcapt19]

I believe part of the reason that the flexible cord is not allowed above a ceiling is because of the toxic fumes. If the cord is within a raceway and no part of it exposed then I would think you are okay.

It is my opinion that the issue of toxic fumes from the wiring methods is not a real issue...the finishes and furnishings of the structure will produce 100s to 1000s of times more toxic smoke than will the wiring system of that building.

Not sure if there are other reasons for not allowing this install. I have heard the NEC wants the cable visible so that it an be inspected from damage - the old rubber cord used to dry out in attics but above a ceiling I doubt it would be an issue. I would get an authority having jurisdiction call on it.

I think this is still a real issue. I have seen cords less than 10 years old installed in conditioned spaces where the jacket and conductor insulation was so brittle that it would break off if you moved the cord.

 

[iwire]

I think this is still a real issue. I have seen cords less than 10 years old installed in conditioned spaces where the jacket and conductor insulation was so brittle that it would break off if you moved the cord.

I have seen the same.

I think it is time to do away with most of our use of rubber cord and switch to more PVC jacketed cords.

I used to work with some German flexible cord that had been left outside for at least 25 years in full sun, in snow and while some spots might get stiff it would not crack. When I would strip it the conductors inside looked brand new, still covered in a talc.