Low voltage wiring in an air duct

[bdgarcia]

Is it legal to run low voltage (CAT5 & RG6 Coax) in an air conditioning duct in a residence?

Thank you
Bryan

 

[ryan_618]

Re: Low voltage wiring in an air duct

I don't see that article 300.22 prohibits it, and I know that the mechanical codes (IMC and UMC) don't care what you put in a SFD plenum, other than gas piping. Hope this helps

 

[jro]

Re: Low voltage wiring in an air duct

If its in the flex-duct or hard duct I would have to say no, but if its in a return air space/plenum, if its plenum rated I would say its ok.

 

[don_resqcapt19]

Re: Low voltage wiring in an air duct

See 800.50 for the Cat-5 and 820.50 for the coax. If the cable is "plenum" rated it is permitted in the duct. Look closely as the wording in these sections at it requires "plenum" rated cable in "other spaces used for enviromental air".
Don

 

[pierre]

Re: Low voltage wiring in an air duct

Article 725 and Chapter 8 must be the 'lonely chapters'

Pierre

 

[bdgarcia]

Re: Low voltage wiring in an air duct

I am somewhat confused. If I read 300.22 it sounds like you cannot install any type of cable in an air handling duct unless it is in "conduit"

300.22 Wiring in Ducts, Plenums, and Other Air-Handling Spaces.
(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 and liquidtight 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, enclos

But if I read 800.53 it sounds like CMP rated plenum CAT5e cable is allowed:

(A) Plenum. Cables installed in ducts, plenums, and other spaces used for environmental air shall be Type CMP. Abandoned cables shall not be permitted to remain. Types CMP, CMR, CMG, CM, and CMX and communications wire installed in compliance with 300.22 shall be permitted. Listed plenum communications raceways shall be permitted to be installed in ducts and plenums as described in 300.22(B) and in other spaces used for environmental air as described in 300.22(C). Only Type CMP cable shall be permitted to be installed in these raceways.

I am similarly confused by section 820.53 where it sounds like CATVP rated cable is allowed in a plenum:

(A) Plenum. Cables installed in ducts, plenums, and other spaces used for environmental air shall be Type CATVP. Abandoned cables shall not be permitted to remain. Types CATVP, CATVR, CATV, and CATVX cables installed in compliance with 300.22 shall be permitted.

In the case of 800.53 and 820.53 I am also uncertain whether the cables need to be in sometype of raceway or whether as long as I use CMP and CATVP rated cable the cables can be "free standing" in a vertical air duct.

I hope this all makes sense, and someone can show me the errors in my thinking.

Thank you
Bryan

 

[iwire]

Re: Low voltage wiring in an air duct

bdgarcia, Take a look at 90.3 here is part of it.

90.3 Code Arrangement.-------Chapter 8 covers communications systems and is not subject to the requirements of Chapters 1 through 7 except where the requirements are specifically referenced in Chapter 8.------

 

[bdgarcia]

Re: Low voltage wiring in an air duct

iwire,

I see what you are talking about, but the sections I referred to do reference back to 300.22 so I am still uncertain on the requirements.

Thank you for your help. I hope I am not being too dense here.

Bryan