Thread: Electrical conduit in AC Ducts

Out side of this just not being right, is there a code that prohibits this

Similar Threads:

• Electrical service box located in closet
• CPSC Recall: Floor Electrical Outlets
• Flex Conduit
• Hot tub conduit
• Metal ducts

Bill,

First a question: Did you see where those come out the other side someplace?

I ask because it looks like there is a 'large lump' where those two 'enter' the duct, making me suspect they go to a damper control motor, which is outside the duct, with the damper inside the duct.

Hypothetically, would there be any objection to "properly supported" conduit run on the exterior of a duct and below insulation?

Can conduit by "properly" attached to / supported by typical ductwork?

Originally Posted by Michael Thomas

Hypothetically, would there be any objection to "properly supported" conduit run on the exterior of a duct and below insulation?

Hypothetically speaking ... Yes, as the conduit would be open and air could be flowing through the conduit, which could cause condensation within the conduit, and maybe even where the conduit touches the duct.

Can conduit by "properly" attached to / supported by typical ductwork?

Again, hypothetically speaking ... I doubt it. Attaching the conduit straps to the duct would puncture the ducts and cause air leaks. Even if those penetrations where all pookied up, as the duct moves in relation to the conduit, or the conduit moves in relation to the duct, the pookie will no longer seal it up.

Besides, the conduit is required to be supported by/from the structure, with very few exceptions.

Originally Posted by Jerry Peck

Bill,

First a question: Did you see where those come out the other side someplace?

I ask because it looks like there is a 'large lump' where those two 'enter' the duct, making me suspect they go to a damper control motor, which is outside the duct, with the damper inside the duct.

Unfortuantely the duct took up most of the attic and I could not see where they came out.

Originally Posted by william siegel

Unfortuantely the duct took up most of the attic and I could not see where they came out.

Are you sure they ran through, though, and did not terminate there at a damper?

In Miami-Dade county years ago, many circuits were required to be run in conduit, and maybe those go to a damper?

Or are you sure they 'pass through' the duct?

This is from the 2008 NEC. (underlining is mine)
- 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.
- - - FPN: See Article 424, Part VI, for duct heaters.
- - -(A) Ducts for Dust, Loose Stock, or Vapor Removal. No wiring systems of any type shall be installed in ducts used to transport dust, loose stock, or flammable vapors. No wiring system of any type shall be installed in any duct, or shaft containing only such ducts, used for vapor removal or for ventilation of commercial-type cooking equipment.
- - - (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 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 luminaires shall be permitted.

- Equipment. A general term, including material, fittings, devices, appliances, luminaires, apparatus, machinery, and the like used as a part of, or in connection with, an electrical installation.