Conduit used as a passageway over metal framing in ceiling

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KTKArc

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Romex & conduit only as a chase
I have some 30' of 3" PVC conduit. I'm thinking of using it as a multi-circuit chase across the 22' of metal framing in a dropped ceiling. The ceiling is in the center of the house and I need to get a third of the house circuits to the other side. The PVC will be totally concealed in soffits and ceilings. And the circuits will be (gasp) Romex. This would reduce grommets in the steel joists. If necessary the conduit could be 'sliced' open at the top. Is any of this an acceptable chase option for Romex? Other ideas are appreciated. FYI SIP walls & ceiling/roof. Conditioned crawlspace is available but less convenient.
 
KTKArc said:
I need to get a third of the house circuits to the other side.
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Sounds like derating would be involved. More that 3 CCC; 310.15(C)(1)
KTKArc said:
If necessary the conduit could be 'sliced' open at the top
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Why slice?
KTKArc said:
metal framing in a dropped ceiling.
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Is this going to be also Plenum space? PVC can not be used.
Additionally, building code may also prevent use of PVC inside of a building.
 
infinity said:
Even if this is in a house? I think that it's a house. :unsure:
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300.22(B)(C)
PVC will off gas significant toxic fumes when exposed to burning or high temperature approaching the burning/melting temperatures. If in air handling space those fumes will or can travel into other areas thus the concern. Some Muni's will prohibit the use of PVC inside of building beyond incidental entry from an exterior of underground source.
 
tom baker said:
Ok thank you. Why would the conduit be sliced open?
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My thoughts were that it's just supporting the cables and not meant to enclose them so allow any heat to escape. (I've an A.D.D. perspective and can think of some oddly associated things).
 
Fred B said:
300.22(B)(C)
PVC will off gas significant toxic fumes when exposed to burning or high temperature approaching the burning/melting temperatures. If in air handling space those fumes will or can travel into other areas thus the concern. Some Muni's will prohibit the use of PVC inside of building beyond incidental entry from an exterior of underground source.
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Excellent perspective and information!
 
Fred B said:
Sounds like derating would be involved. More that 3 CCC; 310.15(C)(1)

Why slice?

Is this going to be also Plenum space? PVC can not be used.
Additionally, building code may also prevent use of PVC inside of a building.
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Expound on your/official definition of plenum please.
While it is a dropped ceiling in conditioned space, all air handling is in ducts and not in this ceiling, which is not used for air handling/ers or ducts. Ducted mini-splits are on either side of this great room in their own dropped ceilings.
 
I'm getting the idea that my concept for a 'simple' raceway is faulty at best. I'll try to sell the PVC online and use the proceeds for a proper/approved raceway. Suggestions for something that works for residential will be appreciated. Our local supply house is CED.
Thank you all!
 
KTKArc said:
My thoughts were that it's just supporting the cables and not meant to enclose them so allow any heat to escape. (I've an A.D.D. perspective and can think of some oddly associated things).
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I would still see the cables as being installed without maintaining spacing, and requiring ampacity adjustment.
The code does not require the cables be bundled to trigger the ampacity adjustment. It requires the installation to use active methods of maintaining spacing to avoid ampacity adjustment.
 
LarryFine said:
What about that Arlington T-205 plastic trough that's made for crawl spaces?

View attachment 2570224
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I've used those. Nice, easy installation with simple support connections, tees, turns etc. It is also designed in a way to make cable install easier, all the support brackets installed first and simple pull the cable throuigh the supports, then add the bottoms (trays) will just go in by opening the swing hinge of the supports 1 or 2 at a time. No drilling joists, and if dealing with limited access space like a drop ceiling, easy to install as they are only 4-5 ft long per section.
 
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