Running NM
#1
04-15-05, 07:23 AM
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Running NM
My cold air returns to the furnace are in the floor joist bays. When running NM through joists, can I go through a cold air return?
#2
04-15-05, 07:24 AM
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Yes, if you are talking about the short way through, perpendicular to the air flow. Caulk around the holes.
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04-15-05, 08:37 AM
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John,
Can you point me to the code on that one. I have heard of people doing it but I never have as I usually don't see the need..anyway it would have to maintain the fire rating of the item breached....BUT with that said....
Check out Art 300-22(b) in regards to ducts used for Environmental Air.
Can you point me to the code on that one. I have heard of people doing it but I never have as I usually don't see the need..anyway it would have to maintain the fire rating of the item breached....BUT with that said....
Check out Art 300-22(b) in regards to ducts used for Environmental Air.
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04-15-05, 10:54 AM
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Originally Posted by ElectricalMan
Can you point me to the code on that one. I have heard of people doing it but I never have as I usually don't see the need..anyway it would have to maintain the fire rating of the item breached...
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04-15-05, 11:47 AM
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To form the cold air return the HVAC guys fasten sheet metal to the bottom of two adjacent joists to close off a joist bay...so you have the subfloor above, a joist on each side and sheet metal across the bottom to create the plenum. This has been very typical construction here for years.
I notice 300-22(b) has an exception that allows running through a plenum for dwellings if the run is perpendicular to the plenum...that is if I understand the exception correctly. Can someone confirm this?
I notice 300-22(b) has an exception that allows running through a plenum for dwellings if the run is perpendicular to the plenum...that is if I understand the exception correctly. Can someone confirm this?
