*abarry
December 11th, 2003, 11:20 AM
Posted by: abarry
Posted - 01/29/2002 : 20:33:06
I want to wire my house for computer connections and high definition TV. I was thinking of running some of the wiring from my basement through 2 floors to my attic via an air return plenum. CAT5e rated for plenum use is 4 times the cost of regular CAT5e. My local HD electrical department manager said it is a big no no to use a plenum as a wire chase unless the wire is rated for that use. He said the problem is that regular wiring could energize the duct causing a fire.
Is this really a fire hazard? What about coaxial cable and regular bell telephone wire in a cold air return...are they also a no no? Would running some kind of flexible NM conduit in the plenum solve the problem? Or, should I abandon the idea of using the cold air return altogether and start fishing through the walls? Thanks, Austin
--------------------------------------------------------------------------------
#69: Author: transfer, Posted: 10 Sep 2002 09:43 pm
----
Posted by: Wgoodrich
Posted - 01/30/2002 : 12:06:54
The only wiring allowed installed in a cold or hot air duct installed parallel rather than perpendicular would be electrctrical metallic tubing or rigid conduit. You are allowed to install this wiring in an air duct in a dwelling only if you are installing across the air duct a short distance. You are not allowed to install any wiring in an air duct using that air duct as a chase unless it is approved as a hazardous classified wiring system.
I would look for another path. Try looking for closets stacked on top of each other on each floor and create a chase in the back inside corner of those closets. Then you can install anything from plumbing to wiring in that chase. Just box in a corner of those closet making a chase from attic to basement.
Hope this helps
Wg
--------------------------------------------------------------------------------
#70: Author: transfer, Posted: 10 Sep 2002 09:45 pm
----
Posted by: HandyRon
Posted - 01/31/2002 : 10:09:40
Could someone help me with a code reference for the parallel vs perpendicular reference. The plenum rating indicates that the insulation on the cable is low smoke emmision. It is no better or worse of an insulator for electricity.
Ron
--------------------------------------------------------------------------------
#71: Author: transfer, Posted: 10 Sep 2002 09:46 pm
----
Posted by: Wgoodrich
Posted - 01/31/2002 : 12:56:41
HandRon, the following is a copy of that Code section I was referring to. Notice the exception for dwellings allowing perpendicular installation. There are other places in the NEC that allow the perpendicular installation in a duct such as the grounding electrode coductor being water pipes in commercial buildings. Yet the rule below seems to be the one that applies to your question. Also note that in my interpretation the {S} marking as low smoke seems to be the key ingredient in plenum approved wiring style.
2002NEC
300.22 Wiring in Ducts, Plenums, and Other Air-Handling Spaces.
The provisions of this section apply to the installation and uses of electric wiring and equipment 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, enclosed gasketed-type luminaires (fixtures) shall be permitted.
(C) Other Space Used for Environmental Air. This section applies to space used for environmental air-handling purposes other than ducts and plenums as specified in 300.22(A) and (B). It does not include habitable rooms or areas of buildings, the prime purpose of which is not air handling.
Exception: This section shall not apply to the joist or stud spaces of dwelling units where the wiring passes through such spaces perpendicular to the long dimension of such spaces.
(1) Wiring Methods. The wiring methods for such other space shall be limited to totally enclosed, nonventilated, insulated busway having no provisions for plug-in connections, Type MI cable, Type MC cable without an overall nonmetallic covering, Type AC cable, or other factory-assembled multiconductor control or power cable that is specifically listed for the use, or listed prefabricated cable assemblies of metallic manufactured wiring systems without nonmetallic sheath. Other types of cables and conductors shall be installed in electrical metallic tubing, flexible metallic tubing, intermediate metal conduit, rigid metal conduit without an overall nonmetallic covering, flexible metal conduit, or, where accessible, surface metal raceway or metal wireway with metal covers or solid bottom metal cable tray with solid metal covers.
Hope this helps
Wg
--------------------------------------------------------------------------------
#72: Author: transfer, Posted: 10 Sep 2002 09:47 pm
----
Posted by: HandyRon
Posted - 01/31/2002 : 13:35:54
I think 800.53 would allow installation of the right type of cable in a duct.
800.53 Applications of Listed Communications Wires and Cables and Communications Raceways.
Communications wires and cables shall comply with the requirements of 800.53(A) through (F) or where cable substitutions are made in accordance with 800.53(G).
(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.
Ron
--------------------------------------------------------------------------------
#73: Author: transfer, Posted: 10 Sep 2002 09:48 pm
----
Posted by: Wgoodrich
Posted - 01/31/2002 : 19:22:32
HandyRon
Below is what abarry was asking. He is seeking an alternative to installing plenum rated wiring.
Copied from original post.
CAT5e rated for plenum use is 4 times the cost of regular CAT5e. My local HD electrical department manager said it is a big no no to use a plenum as a wire chase unless the wire is rated for that use.
The article you copied and provided is speaking of plenum rated wiring. See below the commentary in the NEC Handbook attached to that 800.53.A article. It should show wiring products listed in 800.53.A is still plenum rated wiring.
2002 Handbook
Section 800.53(A) covers listed plenum communications raceways. These raceways provide limited mechanical protection and ease of installation, but they are limited to Type CMP plenum-rated cable if installed in ducts and plenums.
(
My opinion;
As far as I know even if you install conduit you must still use plenum rated wiring as required in 800.53.B.3 in dwellings.
HandyRon;
Are you saying that the cables listed in 800.53.A are nonplenum rated wiring products?
Wg
--------------------------------------------------------------------------------
#74: Author: transfer, Posted: 10 Sep 2002 09:49 pm
----
Posted by: HandyRon
Posted - 01/31/2002 : 20:46:24
Nope, they are plenum rated.
I posted the info because it seemed that the duct was the way to go for this install. Once you add in the cost for the raceway, the extra cost for the plenum rating washes away. I wanted the poster to realize that in my opinion, there was no restriction to running the plenum rated cable in the duct as it seemed you suggested (perpendicular only).
Ron
Posted - 01/29/2002 : 20:33:06
I want to wire my house for computer connections and high definition TV. I was thinking of running some of the wiring from my basement through 2 floors to my attic via an air return plenum. CAT5e rated for plenum use is 4 times the cost of regular CAT5e. My local HD electrical department manager said it is a big no no to use a plenum as a wire chase unless the wire is rated for that use. He said the problem is that regular wiring could energize the duct causing a fire.
Is this really a fire hazard? What about coaxial cable and regular bell telephone wire in a cold air return...are they also a no no? Would running some kind of flexible NM conduit in the plenum solve the problem? Or, should I abandon the idea of using the cold air return altogether and start fishing through the walls? Thanks, Austin
--------------------------------------------------------------------------------
#69: Author: transfer, Posted: 10 Sep 2002 09:43 pm
----
Posted by: Wgoodrich
Posted - 01/30/2002 : 12:06:54
The only wiring allowed installed in a cold or hot air duct installed parallel rather than perpendicular would be electrctrical metallic tubing or rigid conduit. You are allowed to install this wiring in an air duct in a dwelling only if you are installing across the air duct a short distance. You are not allowed to install any wiring in an air duct using that air duct as a chase unless it is approved as a hazardous classified wiring system.
I would look for another path. Try looking for closets stacked on top of each other on each floor and create a chase in the back inside corner of those closets. Then you can install anything from plumbing to wiring in that chase. Just box in a corner of those closet making a chase from attic to basement.
Hope this helps
Wg
--------------------------------------------------------------------------------
#70: Author: transfer, Posted: 10 Sep 2002 09:45 pm
----
Posted by: HandyRon
Posted - 01/31/2002 : 10:09:40
Could someone help me with a code reference for the parallel vs perpendicular reference. The plenum rating indicates that the insulation on the cable is low smoke emmision. It is no better or worse of an insulator for electricity.
Ron
--------------------------------------------------------------------------------
#71: Author: transfer, Posted: 10 Sep 2002 09:46 pm
----
Posted by: Wgoodrich
Posted - 01/31/2002 : 12:56:41
HandRon, the following is a copy of that Code section I was referring to. Notice the exception for dwellings allowing perpendicular installation. There are other places in the NEC that allow the perpendicular installation in a duct such as the grounding electrode coductor being water pipes in commercial buildings. Yet the rule below seems to be the one that applies to your question. Also note that in my interpretation the {S} marking as low smoke seems to be the key ingredient in plenum approved wiring style.
2002NEC
300.22 Wiring in Ducts, Plenums, and Other Air-Handling Spaces.
The provisions of this section apply to the installation and uses of electric wiring and equipment 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, enclosed gasketed-type luminaires (fixtures) shall be permitted.
(C) Other Space Used for Environmental Air. This section applies to space used for environmental air-handling purposes other than ducts and plenums as specified in 300.22(A) and (B). It does not include habitable rooms or areas of buildings, the prime purpose of which is not air handling.
Exception: This section shall not apply to the joist or stud spaces of dwelling units where the wiring passes through such spaces perpendicular to the long dimension of such spaces.
(1) Wiring Methods. The wiring methods for such other space shall be limited to totally enclosed, nonventilated, insulated busway having no provisions for plug-in connections, Type MI cable, Type MC cable without an overall nonmetallic covering, Type AC cable, or other factory-assembled multiconductor control or power cable that is specifically listed for the use, or listed prefabricated cable assemblies of metallic manufactured wiring systems without nonmetallic sheath. Other types of cables and conductors shall be installed in electrical metallic tubing, flexible metallic tubing, intermediate metal conduit, rigid metal conduit without an overall nonmetallic covering, flexible metal conduit, or, where accessible, surface metal raceway or metal wireway with metal covers or solid bottom metal cable tray with solid metal covers.
Hope this helps
Wg
--------------------------------------------------------------------------------
#72: Author: transfer, Posted: 10 Sep 2002 09:47 pm
----
Posted by: HandyRon
Posted - 01/31/2002 : 13:35:54
I think 800.53 would allow installation of the right type of cable in a duct.
800.53 Applications of Listed Communications Wires and Cables and Communications Raceways.
Communications wires and cables shall comply with the requirements of 800.53(A) through (F) or where cable substitutions are made in accordance with 800.53(G).
(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.
Ron
--------------------------------------------------------------------------------
#73: Author: transfer, Posted: 10 Sep 2002 09:48 pm
----
Posted by: Wgoodrich
Posted - 01/31/2002 : 19:22:32
HandyRon
Below is what abarry was asking. He is seeking an alternative to installing plenum rated wiring.
Copied from original post.
CAT5e rated for plenum use is 4 times the cost of regular CAT5e. My local HD electrical department manager said it is a big no no to use a plenum as a wire chase unless the wire is rated for that use.
The article you copied and provided is speaking of plenum rated wiring. See below the commentary in the NEC Handbook attached to that 800.53.A article. It should show wiring products listed in 800.53.A is still plenum rated wiring.
2002 Handbook
Section 800.53(A) covers listed plenum communications raceways. These raceways provide limited mechanical protection and ease of installation, but they are limited to Type CMP plenum-rated cable if installed in ducts and plenums.
(
My opinion;
As far as I know even if you install conduit you must still use plenum rated wiring as required in 800.53.B.3 in dwellings.
HandyRon;
Are you saying that the cables listed in 800.53.A are nonplenum rated wiring products?
Wg
--------------------------------------------------------------------------------
#74: Author: transfer, Posted: 10 Sep 2002 09:49 pm
----
Posted by: HandyRon
Posted - 01/31/2002 : 20:46:24
Nope, they are plenum rated.
I posted the info because it seemed that the duct was the way to go for this install. Once you add in the cost for the raceway, the extra cost for the plenum rating washes away. I wanted the poster to realize that in my opinion, there was no restriction to running the plenum rated cable in the duct as it seemed you suggested (perpendicular only).
Ron