Ping Jake NEC Question


Hi Jake
Any light on the subject would be appreciated. I presently installing an environmental test chamber in Dublin Ohio. the chamber is ten foot high and a drop ceiling will be installed around the chamber at the eight foot level with an additional three foot above the chamber it self. The space above the drop ceiling is used as a plenum for the AC system. The local city inspector is busting our chops because we are using polypropylene conduit for some lighting and control circuitsabove the chamber. He says this product can not be used. http://cableorganizer.com/wire-loom/flame-retardant-wireloom.htm
If you agree could you lead me to the Nec section that covers this. I have already changed all of it out to BX. if he's wrong I like to school him. Two men ten man hours each you could see where I coming from. UL is one of our customer and we have used this same type of install with them and there was not any problems. He coming back tomorrow to re inspect.
Thanks
Barry
Thermal Product Solutions
PS The inspector could not tell the exact code he was enforcing.
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2005 NEC
300.22 Wiring in Ducts, Plenums, and other Air Handling Spaces. The provisions of this section apply to the installation and uses of electrical wiring and equipment in ducts, plenums, and other air-handling spaces.
(B) Ducts or Plenums Used for Environmental Air. Only wiring methods consisting of Type MI cable, Type MC cable employing a smooth or corrugated impervious metal sheath without an overall nonmetallic covering, electrical metallic tubing, flexible metallic tubing, intermediate metal conduit, or rigid metal conduit without an overall nonmetallic covering shall be installed in ducts or plenums specifically fabricated to transport environmental air. Flexible metal conduit shall be permitted, in lengths not to exceed 1.2 m (4 ft), to connect physically adjustable equipment and devices permitted to be in these ducts and plenums chambers. The connectors used with flexible metal conduit shall effectively close any openings in the connection. Equipment and devices shall be permitted within such ducts or plenum chambers only if necessary for their direct action upon, or sensing of, the contained air. Where equipment or devices are installed and illumination is necessary to facilitate maintenance and repair, enclosed gasketed-type luminaries (fixtures) shall be permitted.
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wrote:

Thanks fellas for the info, like I said we did it over so we'll pass But, I hate when their right. Once again a nice surprise about the drop celing being installed around the room. I would say that would be a nice thing to Know before the chamber is engineered.
Thanks Again
Barry
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Barry wrote:

Barry... sorry for the late reply.
As Paul said, 300.22(b) limits you as follows:
B) Ducts or Plenums Used for Environmental Air: Only wiring methods consisting of Type MI cable, Type MC cable employing a smooth or corrugated impervious metal sheath without an overall nonmetallic covering, electrical metallic tubing, flexible metallic tubing, intermediate metal conduit, or rigid metal conduit without an overall nonmetallic covering shall be installed in ducts or plenums specifically fabricated to transport environmental air. Flexible metal conduit shall be permitted, in lengths not to exceed 1.2 m (4 ft), to connect physically adjustable equipment and devices permitted to be in these ducts and plenum chambers.
The key here is "Environmental air". We've used poly cable systems before in test chamber plenums... completely acceptable if they are NOT "normally" occupied spaces.
The reason for .22 is to eliminate products that would contribute smoke and combustible material to a plenum.
Jake
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wrote:

Thanks Jake for your reply.
Could you, Paul, or KJPro explain this section:
Flexible metal conduit shall be permitted, in lengths not to exceed 1.2 m (4 ft), to connect physically adjustable equipment and devices permitted to be in these ducts and plenum chambers. IS BX legal over four feet? All of Sparky's lighting is run with bx. As is everything we replaced. We passed the inspection.
The General is in trouble on this one. Mechanical inspection was in today. The lab is on the second floor with a flat roof above. All of the roof drains are PVC. OOPS!!!!!. They were expecting occupancy on Monday. I think not. Thanks again for your help.
Paul and KJPro no disrepect intended. But, when I think of code Jake immediately comes to mind.
Barry
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