Return chase/electrical

[brianmiller]

The first picture shows a return chase.

The second pictures shows electrical wiring for the blower.

Because there is no separation, to me the electrical wiring is therefore in the return chase, which I was taught is improper.

Is this setup okay?

[David Bell]

The blower wiring is in the confines of the air handler, and presumably has been design certified by CSA. Any plenums, ductwork, or return chases are field installed attachments.

[James Duffin]

I don't think PVC is rated for a plenum since it puts off toxic fumes when it burns.

[David Bell]

I don't think PVC is rated for a plenum since it puts off toxic fumes when it burns.
Same with the armaflex on the suction line, I doubt the control wire is plenum rated either.

[RobertSmith]

PVC and armaflex is used here in Austin all the time. City allows it. I've never seen anything to not allow these things in the return chase.

[Jerry Peck]

PVC and armaflex is used here in Austin all the time. City allows it. I've never seen anything to not allow these things in the return chase.


None of those things should be in the return air plenum, not only the PVC but the ABS(?) it is attached to, also all plenum rated low voltage cable I recall seeing has been white, not brown.

The underside and cut-out edges of the plywood platform should also be lined/sealed to not expose the wood, and the air handler needs to be sealed to the platform.

The wiring in the air handler unit is part of the listed and labeled equipment, and as such there is no problem with it being in the listed and labeled equipment - it was tested, listed and labeled with that wiring in there.

[Rod Butler]

PVC and armaflex is used here in Austin all the time. City allows it. I've never seen anything to not allow these things in the return chase.


If you think about it the occupied space is essentially a return air plenum. LOTS of stuff there is PVC and worse.

I'd have to see a code section that dis-allows it before I would call it.

[David Bell]

IMC 602.2.1 Materials exposed within plenums. Except as required in section 602.1.1through 602.2.1.5 materials exposed within plenums shall be non combustable or shall have a flame spread index of not more than 25 and a smoke developed index of not more than 50 as tested,

[Rich Goeken]

PVC and armaflex is used here in Austin all the time. City allows it. I've never seen anything to not allow these things in the return chase.


PVC gives off noxious fumes, that's why all wiring to be in a plenum area is "Plenum Rated"---PVC isn't. Sound to me like the City is lax in their inspections. Low voltage wiring can be provided in many colors and still be rated for use in a plenum. Sometimes a contractor may make a "Buy" because the wiring was a special run and all wasn't sold---purple as an example. Exception, red is not used in telecommunications---dedicated for fire detection.