# Luminaires connected to ducts - Intersting



## cdcengineer (Nov 23, 2010)

Here's a new one for me...

Strange new electrical installations are springing up here in Colorado. The legalization of medical marijuana facilities has ignited a market for electrical installations in these establishments. Most, if not all AHJ's/building dept's. are requiring electrical engineer's to stamp the designs. This is now the third design I will have done.

I was approached about a project where the owner wants to install a direct-ducted luminaire which is made by a specialty cultivation company. The luminaire is listed. And it appears the manufacturer intends for it to be installed with 8" duct connected to either end. However, I have never been asked if it was acceptable to install a light connected to a duct. In review of NEC articles 110, 300 &amp; 410, I see only one real obstacle to their request - NEC 300.22(B).

According to the owner and mechanical engineer, this is a common installation practice. I have concerns about the possibility of the luminaire somehow energizing a semi-rigid duct, as there is no way to fasten an equipment ground between the luminaire and duct w/o opening up (and possibly losing the listing) and modifying the internals of the factory wiring.

Moral, political or personal opinions regarding this new industry aside, does anyone know if the IBC or mechanical codes might dis-allow such an installation. Or perhaps an NEC requirement which might either prove or dis-prove this type of installation method?

Thanks for the input


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## wilheldp_PE (Nov 23, 2010)

I'm having trouble envisioning what you are describing, but I do know that there are lay-in troffers that have ducts built into them. This allows for only one opening in a drop ceiling for both a light fixture and a register. If that is what you are talking about, then there are fixtures built specifically for that purpose. If that's not what you are describing, then I don't know the answer to your question.


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## cdcengineer (Nov 24, 2010)

http://www.sunlightsupply.com/hort/product...mp;type=product

They duct these grow lights in order to remove unwanted heat from the space. Fan on one end, intake louver on the other. You may be onto something with the troffers, but I always thought those didn't have ducts connected to them. I thought they were for intake or exhaust into a plenum.


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## rift (Nov 25, 2010)

cdcengineer said:


> http://www.sunlightsupply.com/hort/product...mp;type=product
> They duct these grow lights in order to remove unwanted heat from the space. Fan on one end, intake louver on the other. You may be onto something with the troffers, but I always thought those didn't have ducts connected to them. I thought they were for intake or exhaust into a plenum.


First of all, legalize it maaaaan! OK, that's out of the way. I'm no engineer, but here's my take:

The shop drawing you provided indicates that the duct connects to a remote mounted reflector via cord and plug. The reflector includes the lamp socket only, but not the ballast. Therefore the ballast is not directly connected to the duct. Any fault to ground that occurs will be in the ballast and will then follow the path of the raceway back to the panel. If this summation is acceptable, please inform the Mike Holt Forum as well  !


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## rift (Nov 25, 2010)

rift said:


> duct connects to a remote mounted reflector via cord and plug.


That is, the duct connects to the reflector, and the reflector connects to the ballast via cord and plug.


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## speedyox (Dec 3, 2010)

Coincidentally, those types of lights are in a photo from a recent time magazine article about legalized medicinal marijuana.


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## cdcengineer (Dec 6, 2010)

speedyox said:


> Coincidentally, those types of lights are in a photo from a recent time magazine article about legalized medicinal marijuana.


What's the gist of the article?

It turns out that the duct is not actually connected to light. It is attached with an insulated collar. The building dept. will allow it as both the duct and luminaire are independently supported.


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## speedyox (Dec 6, 2010)

cdcengineer said:


> speedyox said:
> 
> 
> > Coincidentally, those types of lights are in a photo from a recent time magazine article about legalized medicinal marijuana.
> ...



Here it is: http://www.time.com/time/nation/article/0,...2030768,00.html

And the photos: http://www.time.com/time/photogallery/0,29...2209202,00.html


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## pelaw (Dec 9, 2010)

There are no problems other than those of listing.

Lights must be supported from structure and not from ducts, unless the whole piece is listed for installation together. The 300.20 is not a problem. The system must be and will be grounded and that takes care of it.


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