FMC in plenums

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rlundsrud

Senior Member
Location
chicago, il, USA
Since sealtite is not allowed in plenums, can you use FMC in a plenum as long as the cable inside it is rated for use within plenums? I can't find anything that tells me I shouldn't, but I would like some reassurance. The cable(s) in question would be control wiring for BAS temp controls. The FMC would be properly supported and in lengths of less than 6' except perhaps for fishing a wall.
 

infinity

Moderator
Staff member
Location
New Jersey
Occupation
Journeyman Electrician
Is this in Chicago?

Doesn't Chicagoland have their own more restrictive code when it comes to spaces used for environmental air? I seem to remember installing recessed lighting that had flexible metallic tubing (FMT) instead of FMC and they were approved for use in Chicago.
 

hbiss

EC, Westchester, New York NEC: 2014
Location
Hawthorne, New York NEC: 2014
Occupation
EC
Just off the top of my head I wouldn't think sealtite is allowed in a plenum space because of the plastic covering that is not plenum listed. Why not use greenfield (FMT)? Is it a wet or damp location?

-Hal
 

rlundsrud

Senior Member
Location
chicago, il, USA
Just off the top of my head I wouldn't think sealtite is allowed in a plenum space because of the plastic covering that is not plenum listed. Why not use greenfield (FMT)? Is it a wet or damp location?

-Hal

Sealtite is not allowed, I mentioned that at the beginning of the post. My question was can I use greenfield in a plenum if the cables contained within are plenum rated. I cannot see a reason that prevents the use.
 

infinity

Moderator
Staff member
Location
New Jersey
Occupation
Journeyman Electrician
Just off the top of my head I wouldn't think sealtite is allowed in a plenum space because of the plastic covering that is not plenum listed. Why not use greenfield (FMT)? Is it a wet or damp location?

-Hal

"Greenfield" is a slang term for FMC. FMT is a completely different product {Article 360}, unlike FMC it's liquidtite which also makes it far more airtight than FMC.
 

1964element

Senior Member
Location
Chicago
It's like Greenfield you bend it holds it own shape and fittings screw it and has gaskets. Used in Chicago everything is compression.

Sent from my E6782 using Tapatalk
 

mgookin

Senior Member
Location
Fort Myers, FL
It looks like some FMC is ok and some is not.

For example:
http://www.southwire.com/products/AlfexTypeRWA.htm includes the spec:
[h=2]Applications[/h]
Alflex® Type RWA (Reduced Wall Aluminum) Flexible Metal Conduit is suitable
for the following installations:


  • Power and lighting branch circuit conductors and cables for connecting
    receptacles, luminaires, equipment, office partitions, etc.
  • Metal raceway for wires and cables per NEC (ANSI/NFPA-70) Article 348
  • Motor feeder, branch, and control circuit conductors and cables
  • Class 1, Class 2, Class 3 Remote-control, signaling, and power-limited
    circuit conductors and cables
  • Fire alarm system conductors and cables of power-limited or
    non-power-limited fire alarm circuits
  • Environmental air-handling spaces per NEC 300.22(C)
  • Voice, data, communications and video cables including CATV and optical
    fiber cables
  • Concealed or exposed installations per NEC Article 348 and the applicable
    NEC provisions
  • Elevators, hoistways, and escalators per NEC 620.21
  • As a grounding conductor for lengths up to 6 feet (20A max) as per 2005 NEC
    250.118(5)
  • Electric signs and outline lighting per NEC 600.7, 600.31 (1000 volts or
    less), and 600.32 (>1000 volts)
  • Hazardous location, Class 1, Div. 2, for flexible connectors only per 2005
    NEC 501.10(B)(2) & 501.30(B)
  • UL 1, 2, & 3 Hour Through-Penetration Firestop Sytems: C-AJ-1462,
    C-AJ-1463, C-AJ-1464, W-L-1308, and W-L-1309
 

rlundsrud

Senior Member
Location
chicago, il, USA
Let's take the Chicago code out of the equation as not many people on this forum are well versed in it. I can't seen to find a code that specifically prohibits the use of FMC in a plenum if the cable is rated for use in that space.
 
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