Plenum Box installation: SO cord

[iwire]

What separates those for the suggested installation of your projector mount is the plenum, and and accessibility

Mark, IMO the plenum issue has little to do with it as the NEC is written for all applications and in my area not all areas above suspended ceilings are used for air handling. Also 300.22 directly addresses wiring methods in air handling spaces.


My only point in this thread has been pointing out the code sections as they relate to the OPs drawing. Personally I do not see a safety issue as the projector will be replaced long before the cord becomes compromised.

IMHO a code change should be made to clearly allow the type of installation proposed by the OP. :smile:

 

[soundcon]

If it (the drawing you posted) came from them - they need new tech support - not the one in Bangladesh.... Or you may be you may have misunderstood, as there would be a 1G metal cut-in box inside the plenum cover - but installed in the method shown by realolman....

Anyway, my point about the floor access boxes is that the outlet is below the floor line - but is not in the floor - it is in the recessed (niche) access box that happens to be inside the floor.... Cords do not enter the floor and travel around the framing.

The DaLite product is not intended to act in the same way - or from my read of their spec's - promoted in a way to suggest that, although the instructions are particularly vague.... If you got that impression there must be some confusion of someones part, yours, or theirs....

Now for some more discussion about cords behind finishes.... Here are some examples of where it is done, and often....

• Jacuzzi Tubs - most often the cord fed motor and controls are behind an access in the tub-surround skirting.
• Hot-tubs, same thing...
• Floor access boxes of course
• Enclosures for networking, structured wiring etc.
• Cord connected items behind access panels.

What separates those for the suggested installation of your projector mount is the plenum, and and accessibility without disassembling the mount. If you say had an enclosure adjacent with a grommeted hole for the cords, an outlet inside it and sealed from the plenum, but more importantly accessible from below the cieling - IMO that would be OK as it would be much like a floor access box, but in the cieling.... Something like below... I'm sure there'll be some discussion about it....

The drawing is mine and not from Da-Lite. They provide very little by way of information about this box. Possibly that is so that they can stay clear of recommending a particular application technique. I drew this up to show what we would like to do and try to get a reason why we can't. All of the reasons given here are based on varying pieces if code statements and some really good underlying substantiating evidence but I still think that this installation would not be a problem in real life but for us to use it apparently requires an exception be added to the code, if that is even possible. Jim

 

[e57]

My only point in this thread has been pointing out the code sections as they relate to the OPs drawing. Personally I do not see a safety issue as the projector will be replaced long before the cord becomes compromised.

IMHO a code change should be made to clearly allow the type of installation proposed by the OP. :smile:

The accessiblity of the outlet j-box is the only issue I see really wrong with the proposed install, and that the cord is passing thought the ceiling to do so... I see it more as a 314.29 issue

 

[e57]

The drawing is mine and not from Da-Lite. They provide very little by way of information about this box. Possibly that is so that they can stay clear of recommending a particular application technique. I drew this up to show what we would like to do and try to get a reason why we can't. All of the reasons given here are based on varying pieces if code statements and some really good underlying substantiating evidence but I still think that this installation would not be a problem in real life but for us to use it apparently requires an exception be added to the code, if that is even possible. Jim

Ahhhh, I thought so.... And I aggree it seems they leave quite abit to the imagination obout the install, but don't suggest your concept.... I think you got a number of reasons why you can't, but if willing to put in an NEC proposal, wait several years, and still have it knocked down as it flies in the face of, and contradicts so many other codes, so be it.... Personally I would seek approval for the option I gave you with your AHJ for approval - or put the outlet on the face of the ceiling....

 

[stickboy1375]

The reasoning was presented earlier in the thread but a synopsis here is that we want to hide the receptacle to make a cleaner more attractive installation. We can make almost everything disappear if we can figure out a way to get the A/C connection in the plenum box. for more detail see my inital couple of posts. Jim

Okay, now i'm really confused, you have no problem with a projector hanging from the ceiling, but a receptacle is out of the question? God help me....

 

[mxslick]

Okay, now i'm really confused, you have no problem with a projector hanging from the ceiling, but a receptacle is out of the question? God help me....

It's not the OP with the issue with the recept but the end user, who doesn't like to see a recept. in the ceiling.

Until the Code is amended I usually have to tell my clients (in a polite way of course) tough tooties, the recep. HAS to be there. I do clean things up, by installing right-angle cord caps and cutting (Oh, the humanity....) the projector's power cord to the correct length.

I'll try to get some example pics of my installs soon to show what I mean.

As for the OP and the Da-Lite mount, I don't see any safety issues at all. First off, the power cord is fully encased (with ample breathing room to boot) within the steel riser pipe. The projector can be readily disconnected for service or in an emergency by the IEC connector on the exposed end of the cord. The ONLY possible failure hazard would be the cord itself, but again it's enclosed in enough metal that I don't see a significant fire hazard.

Finally, average service life of a video projector is about 5-7 years anyway, not enough time for the cord to break down in the ambient environment that the projector would tolerate.

Hmmm, maybe I should draft that Code change proposal...

EDITED TO ADD:

Personally I do not see a safety issue as the projector will be replaced long before the cord becomes compromised.

Wow, Bob and I actually see eye-to-eye on something.

 

[soundcon]

Okay, now i'm really confused, you have no problem with a projector hanging from the ceiling, but a receptacle is out of the question? God help me....

Apparently you have not had the priveledge of seeing the way some A/V installers leave their projector installations. Cords running 4ft to a tile in another zip code, power cables cable wound up and cable tied along with a bunch of video input and control cables. I mentioned all of this in a earlier post. I take great pride in the quality and apperarance of my installs. I do my best to hide all of that ugly cabling. Yes the projector is exposed but to me and my high end customers, the receptacle is not a thing of beauty. IF there is a SAFE way to eliminate the rediculous look of the wires I intend to find it. To me there is a huge difference between the projector hanging by itself and a bunch of ugly wire adorning it. Jim

 

[soundcon]

It's not the OP with the issue with the recept but the end user, who doesn't like to see a recept. in the ceiling.

Until the Code is amended I usually have to tell my clients (in a polite way of course) tough tooties, the recep. HAS to be there. I do clean things up, by installing right-angle cord caps and cutting (Oh, the humanity....) the projector's power cord to the correct length.

I'll try to get some example pics of my installs soon to show what I mean.

As for the OP and the Da-Lite mount, I don't see any safety issues at all. First off, the power cord is fully encased (with ample breathing room to boot) within the steel riser pipe. The projector can be readily disconnected for service or in an emergency by the IEC connector on the exposed end of the cord. The ONLY possible failure hazard would be the cord itself, but again it's enclosed in enough metal that I don't see a significant fire hazard.

Finally, average service life of a video projector is about 5-7 years anyway, not enough time for the cord to break down in the ambient environment that the projector would tolerate.

Hmmm, maybe I should draft that Code change proposal...

EDITED TO ADD:



Wow, Bob and I actually see eye-to-eye on something.

Hey, I am all for you submitting the concept for a code change. I'll even help with drawings or mock-up or other submittals. I think an acceptable alternative is available here and should be persued. Jim

 

[benaround]

Soundcon,

What you need is something similar to a 'lay-in fixture' with the recpt. installed

so it can be acessed from below. Then the plenum is a non-issue. jmo

 

[e57]

I do my best to hide all of that ugly cabling. Yes the projector is exposed but to me and my high end customers, the receptacle is not a thing of beauty. IF there is a SAFE way to eliminate the rediculous look of the wires I intend to find it. To me there is a huge difference between the projector hanging by itself and a bunch of ugly wire adorning it. Jim

So do we.... But we hope you leave a card when you bury a receptical in a projector mount - so we know where to look for you.... Dare I say though, what you need is a product that does not yet exist - a hard-wired projector mounting with a short IEC whip. Or a projector with a 1/2" KO on the top... The chances of changing the code are slim and none - but are better say making a custom product, and getting it listed....

 

[peter]

"...we want to hide the receptacle to make a cleaner more attractive installation."
1] Artists rarely have written books but Paul Klee wrote "The Thinking Eye". I doubt if any designer has read it. Perhaps, if they did, they would have a better perspective of the real world. Why would it somehow be objectionable to have a receptacle on the ceiling but not objectionable to have receptacles in all the walls and perhaps also in the floor?
2] In the existing design, the cord is visible. It has a big, "ugly" connector plugged into the projector. None of this seems to be objectionable. Yet, the poor, poverty stricken receptacle with an ordinary plug somehow is. How streamlined is this?
3] The objection of the Code is because of the cord being above the suspended ceiling. Is it possible to replace the rubber cord with a piece of MC cable? 14/2 should be able to fit into an industrial plug/receptacle combibation.
4] Since you have a sealed plenum metal chamber and a 1 1/2" nipple already there, why not just wire it with bare #14 THHN. It's all enclosed anyway. If you need a disconnect, you can always use a switch. [A switch, not being a receptacle, would not fit a designer's definition of "ugly".
Just trying to muddy the waters.
~Peter

 

[alfiesauce]

Here is a drawing of the installation:

Now it seems like everybody is in agreement that this does not meet code.
What if there was an access panel placed underneath the receptacle within the plenum approved box? Therefore giving you access to the receptacle to be able to disconnect it without having to take the whole projector mount apart?
That would seem to me as being a reasonable solution when compared to access you have when dealing with the receptacles underneath whirlpool tubs, or the receptacle for a dishwasher placed underneath the unit, etc., etc..

 

[e57]

What if there was an access panel placed underneath the receptacle within the plenum approved box? Therefore giving you access to the receptacle to be able to disconnect it without having to take the whole projector mount apart?
That would seem to me as being a reasonable solution when compared to access you have when dealing with the receptacles underneath whirlpool tubs, or the receptacle for a dishwasher placed underneath the unit, etc., etc..

Mentioned that earlier, but I assume an access panel in the ceiling is equally 'ugly'????? Cords are cords, and you cant polish a turd - so they say.... But I also assume that you could wait for it to dry, and give in a good coat of shellac...

 

[soundcon]

Soundcon,

What you need is something similar to a 'lay-in fixture' with the recpt. installed

so it can be acessed from below. Then the plenum is a non-issue. jmo

We are using that configuration now. We are trying to get rid of the receptacle and excess exposed cable by putting them in the plenum box above the ceiling. Since the projectors all have IEC connectors on them and can as quickly be disconnected at the projector as at the ceiling I see no reason why we can't conceal the receptacle and plug in the box. Especially if plenum is not the issue. I fail to see where the safety hazzard is in the proposed installation. The UL approved cable, receptacle and plug are all fully encased in sealed metal with no possibility of a fire reaching the plenum area, ceiling materials or below the ceiling line. There is an emergency disconnect point at the projector to allow for service/removal.

Please understand I am not arguing that this is to current code. I am suggesting that the code was not written with this kind of installation in mind/available and possibly this should be considered. With more and more interest in technology and increased consideration to make things esthetically pleasing, unless there is a safety issue somewhere, new configurations like this one should be studied and if at all possible the code be modified to allow safe new installation techniques. Jim

 

[don_resqcapt19]

Please understand I am not arguing that this is to current code. I am suggesting that the code was not written with this kind of installation in mind/available and possibly this should be considered. With more and more interest in technology and increased consideration to make things esthetically pleasing, unless there is a safety issue somewhere, new configurations like this one should be studied and if at all possible the code be modified to allow safe new installation techniques. Jim

Jim,
Send in a proposal. There is a form in the back of your code book. Proposals for the 2011 code must be received by the NFPA before 5pm on 11/7/08.

 

[e57]

Since the projectors all have IEC connectors on them and can as quickly be disconnected at the projector as at the ceiling I see no reason why we can't conceal the receptacle and plug in the box. Especially if plenum is not the issue. I fail to see where the safety hazzard is in the proposed installation. The UL approved cable, receptacle and plug are all fully encased in sealed metal with no possibility of a fire reaching the plenum area, ceiling materials or below the ceiling line. There is an emergency disconnect point at the projector to allow for service/removal.

What still would have is a J-box concealed unless there is access from below, and why it would not make it as a code change is that it flies in the face of the codes below.... You may have to change both....

314.29 Boxes and Conduit Bodies to Be Accessible.
Boxes and conduit bodies shall be installed so that the wiring contained in them can be rendered accessible without removing any part of the building or, in underground circuits, without excavating sidewalks, paving, earth, or other substance that is to be used to establish the finished grade.
Exception: Listed boxes shall be permitted where covered by gravel, light aggregate, or noncohesive granulated soil if their location is effectively identified and accessible for excavation.
Consideration should be given to the accessibility of junction boxes installed on a structural ceiling above a suspended ceiling. A box is permitted to be used at any point for the connection of conduit, tubing, or cable, provided it is not rendered inaccessible. See Article 100 for the definition of accessible (as applied to wiring methods). See 300.15 for other requirements for boxes, conduit bodies, or fittings.

400.8 Uses Not Permitted.
Unless specifically permitted in 400.7, flexible cords and cables shall not be used for the following:
(1) As a substitute for the fixed wiring of a structure
(2) Where run through holes in walls, structural ceilings, suspended ceilings, dropped ceilings, or floors
(3) Where run through doorways, windows, or similar openings
(4) Where attached to building surfaces
Exception: Flexible cord and cable shall be permitted to be attached to building surfaces in accordance with the provisions of 368.8.
(5) Where concealed by walls, floors, or ceilings or located above suspended or dropped ceilings
(6) Where installed in raceways, except as otherwise permitted in this Code
The flexible cords and cables referred to in Article 400 are not limited to use with portable equipment. They may not be used, however, as a substitute for the fixed wiring of a structure or where concealed behind building walls, floors, or ceilings (including structural, suspended, or dropped-type ceilings). See 240.5 and 527.4(B) and (C) for the uses of multiconductor flexible cords for feeder and branch-circuit installations, and for overcurrent protection requirements for flexible cord. See 410.30 for cord-connected luminaires.

Accessible (as applied to wiring methods). Capable of being removed or exposed without damaging the building structure or finish or not permanently closed in by the structure or finish of the building.

If you can get access from above - that would be up to your AHJ... But would be considered "above the ceiling" by many if not accessable from below...

 

[benaround]

Soundcon,

I don't think anyone has a problem with your set-up, it looks very safe. The

problem is just the words that make it non-compliant. I'd bet that if someone

produced a m.c. type of whip with the proper terminals, that they could sell

a few of them.

 

[soundcon]

"...we want to hide the receptacle to make a cleaner more attractive installation."
1] Artists rarely have written books but Paul Klee wrote "The Thinking Eye". I doubt if any designer has read it. Perhaps, if they did, they would have a better perspective of the real world. Why would it somehow be objectionable to have a receptacle on the ceiling but not objectionable to have receptacles in all the walls and perhaps also in the floor?
2] In the existing design, the cord is visible. It has a big, "ugly" connector plugged into the projector. None of this seems to be objectionable. Yet, the poor, poverty stricken receptacle with an ordinary plug somehow is. How streamlined is this?
3] The objection of the Code is because of the cord being above the suspended ceiling. Is it possible to replace the rubber cord with a piece of MC cable? 14/2 should be able to fit into an industrial plug/receptacle combibation.
4] Since you have a sealed plenum metal chamber and a 1 1/2" nipple already there, why not just wire it with bare #14 THHN. It's all enclosed anyway. If you need a disconnect, you can always use a switch. [A switch, not being a receptacle, would not fit a designer's definition of "ugly".
Just trying to muddy the waters.
~Peter

D, and a fine muddier your are to, I might say. Actually I would not mind having an access panel available from the room side so that we would not have to pop a ceiling tile to get to our gear. However, no one is making a product for us like that as far as I can tell so I am trying to work with the cards I have been delt. I have a projector mount that fits immediately behind the ceiling tile and is not visable from the room. There is a plenum box made to fit on the mounting bracket. All of the video and control cables run up through the 1 1/2" NPT pipe. All in all we can get the wires to look fairly clean by putting flex sheathing over them.

Actually, the receptacle does not look very pretty and really stands out hanging down from an otherwise clear and white ceiling. In the case of exposed receptacles on the wall, there is a huge difference. Most receptacles on the wall can be covered with a piece of furniture. Hard to put a curio cabinet on the ceiling. And the receptacles we install on the floor are recessed into a floor box, the lids of whihch are covered with matching carpet virtually making invisible and out of sight. big difference from the receptacle in the ceiling with the plug and cable hanging down. And yes, I would love to hide the projector entirely every time but I can't. So I still like to make the installation look spectacular anyway. A nice meeting room or classroom does not have to look like my shop.

I might be willing to use the THHN and cover it with the mesh if I could find a suitable IEC female connector to connect to the Projector. I may look into this possibility and see if I can get it past the powers to be.

As for the big ugly connector on the projector... You have not looked and some of the new projectors. They have gotten real good at recessing the male connector and having the cord connector recessed as well and mostly out of sight. The projector manufacturers have become more sensitive to the fact that their device is exposed and not very pretty.

Thanks for the mud. Jim

 

[soundcon]

So do we.... But we hope you leave a card when you bury a receptical in a projector mount - so we know where to look for you.... Dare I say though, what you need is a product that does not yet exist - a hard-wired projector mounting with a short IEC whip. Or a projector with a 1/2" KO on the top... The chances of changing the code are slim and none - but are better say making a custom product, and getting it listed....

Actually I have requested some attention from DaLite on this situation but if they will take the lead on this or not is another matter. Until they or someone else submit and receive approval on a suitable product we are stuck..... for the moment. I may work on the ides of a suitable whip of some sort. An then again, with the size of LCD/plasma getting larger and more cost effective, we may find that we are installing substantially fewer projectors and the issue becomes mute.

 

[weressl]

We are installing a ceiling mounted projector using a Da-Lite mfg product specified for plenum use. This device is NOT UL listed. The mfg lists this product as housing an electrician installed handy box with receptacle. The cord from the projector is run through the 1 1/2" NPT mounting pipe directly into the plenum box which is an integral assembly with the projector mount, and then plugs into the provided receptacle.

The local inspector indicates that this is not in compliance with code and cites the NEC 400.8 item 5. He also indicates that the installation might be acceptable if the plenum box/mounting assembly wer to be UL approved. The mfg vehemently declares that the configuration is in compliance with code and UL approval is not required. We are in the middle.

I have two questions: 1. Is the inspector is correct that this is not an acceptable installation? 2. Is there another way to configure this where we do not have to have the receptacle exposed to the room on the ceiling side?

Any help leading us to a better cleaner installation will be appreciated. Jim

I would think that a twist-lock receptacle mounted through the ceiling would be perfectly fine. The inspector has NOTHING to do with what is being plugged into the receptacle, their are of responsibility ends with the permanent installation.

I suggest twistlock so it does not fall out even though the receptacles are designed with a spring action to prevent the blade from falling out, but it is ordinarily for horizontal placement not vertical pull.