Electrical Wiring in Return Chases

[brianmiller]

Is it a code violation if there are electrical cables routed through a return chase?

Thanks,

b

[Jim Port]

What type of wiring method? Are they run perpendicular or lengthwise in the return?

[brianmiller]

duh...photo would help.....

[Bob Elliott]

Wrong because they are not and can not be fastened properly.
Not because they are in a chase but because the are simply hanging.

Unless someone knows of a violation on them running in a chase with proper clearance.

[Jerry Peck]

From the 2008 NEC:
- 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.
- - (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.
- - - FPN: The space over a hung ceiling used for environmental air-handling purposes is an example of the type of other space to which this section applies.
- - - 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, conductors, and raceways shall be permitted to 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.
- - - - (2) Equipment. Electrical equipment with a metal enclosure, or with a nonmetallic enclosure listed for the use and having adequate fire-resistant and low-smoke-producing characteristics, and associated wiring material suitable for the ambient temperature shall be permitted to be installed in such other space unless prohibited elsewhere in this Code.
- - - - - Exception: Integral fan systems shall be permitted where specifically identified for such use.
- - (D) Information Technology Equipment. Electrical wiring in air-handling areas beneath raised floors for information technology equipment shall be permitted in accordance with Article 645.

[Robert Meier]

NM cable is permitted to travel horizontally through one stud then through the other. {300.22(C)Exception}

[Bob Elliott]

OK ,so from Jerry's code section it is wrong all together.

[brianmiller]

OK ,so from Jerry's code section it is wrong all together.

Bob,

Are you saying that it is wrong all together to have electrical wiring in a return chase , or are you saying that the wiring in the return chase in this specific photo is wrong altogether?

My take on the code is that you can have NM cables in the return chase is properly routed, secured.

b

[Bob Elliott]

(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.

My fault as I may have missed that it is a return so section A) does not apply.

Personally I always try to understand the reasoning behind codes when reading them and it looks as if the rules are to avoid a spark setting off anything flammable.

If this is simply a return chase then maybe it is OK .however perhaps Jerry can explain.

[Jerry Peck]

My take on the code is that you can have NM cables in the return chase is properly routed, secured.

(I have not changed the wording in the code, only separated the code into a more easily read format)

(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.

[Robert Meier]

The NEC wants the smallest amount of cable possible in the chase. This means that it has to go straight through from a hole in one stud through a hole in the next stud.

[brianmiller]

Okay....let's see if I've got it through my thick head....

Based on Jerry's last post, NM electrical cables are not allowed based on NEC 300....however, because of the exception in NEC 300, NM will be allowed if the NM cable has (from Robert's last post) the "smallest amount of cable possible in the chase. This means that it has to go straight through from a hole in one stud through a hole in the next stud"

Do I have it down correctly?

b

[Robert Meier]

Okay....let's see if I've got it through my thick head....

Based on Jerry's last post, NM electrical cables are not allowed based on NEC 300....however, because of the exception in NEC 300, NM will be allowed if the NM cable has (from Robert's last post) the "smallest amount of cable possible in the chase. This means that it has to go straight through from a hole in one stud through a hole in the next stud"

Do I have it down correctly?

b

Yes. :D

[Jerry Peck]

Okay....let's see if I've got it through my thick head....

Based on Jerry's last post, NM electrical cables are not allowed based on NEC 300....however, because of the exception in NEC 300, NM will be allowed if the NM cable has (from Robert's last post) the "smallest amount of cable possible in the chase. This means that it has to go straight through from a hole in one stud through a hole in the next stud"

Do I have it down correctly?

b


Yes. :D

No.

The exception you are referring to does not apply to (B), that exception applies to (C):
- (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.
- - FPN: The space over a hung ceiling used for environmental air-handling purposes is an example of the type of other space to which this section applies.
- - 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) (not copied as it is not applicable to this discussion)
- - (2) (not copied as it is not applicable to this discussion)

The exception applies to (C) which contains this statement: "This section applies to space used for environmental air-handling purposes other than ducts and plenums as specified in 300.22(A) and (B)"

[Bob Elliott]

Gosh ,I can see lots of confusion here including myself.
I do not see the word chase and duct or plenum is what carries the conditioned air so I can see why that would be prohibited.

This is what I am looking at.....
(2) Equipment. Electrical equipment with a metal enclosure, or with a nonmetallic enclosure listed for the use and having adequate fire-resistant and low-smoke-producing characteristics, and associated wiring material suitable for the ambient temperature shall be permitted to be installed in such other space unless prohibited elsewhere in this Code.
- - - - - Exception: Integral fan systems shall be permitted where specifically identified for such use.

[brianmiller]

No.

The exception applies to (C) which contains this statement: "This section applies to space used for environmental air-handling purposes other than ducts and plenums as specified in 300.22(A) and (B)"


Jerry, is your position then that NM cable are not allowed in a return chase under any circumstance?

b

[Kristi Silber]

I thought this was the pertinent bit:



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.



Aren't we talking about a joist cavity?

[Robert Meier]

No.

The exception you are referring to does not apply to (B), that exception applies to (C):
- (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.
- - FPN: The space over a hung ceiling used for environmental air-handling purposes is an example of the type of other space to which this section applies.
- - 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) (not copied as it is not applicable to this discussion)
- - (2) (not copied as it is not applicable to this discussion)

The exception applies to (C) which contains this statement: "This section applies to space used for environmental air-handling purposes other than ducts and plenums as specified in 300.22(A) and (B)"

That space between the studs is defined as a space used for environmental air so the exception does apply.

From the NECH:


The exception to 300.22(C) permits cable to pass through
joist or stud spaces of a dwelling unit, where the joist space
is used as a return for a forced-air central heating or airconditioning
system. As shown in Exhibit 300.20, the joist
space is covered with appropriate material, and the cable
passes through the space perpendicular to the vertical run.
The exception does not permit equipment such as junction
boxes or device enclosures within this space unless the wiring
method employed and enclosure type used meet the requirements
of both 300.22(C)(1) and (C)(2).

[Jerry Peck]

Aren't we talking about a joist cavity?

The photo in the original post looks like a duct on the right next to a stud cavity, and the original poster stated "a return chase" - which I am taking as meaning a duct.

You have raised a good question, though, is it a "(B) Ducts or Plenums Used for Environmental Air" or is it "(C) Other Space Used for Environmental Air. This section applies to space used for environmental air-handling purposes other than ducts and plenums"?

I am taking it as that is a duct next to a wall based on what I am reading in the post, but it may not be. :confused:

[Jerry Peck]

It's taking forever for my computer to post - I've either got a computer problem or an internet problem ... I'm about fed up with it for tonight. I have to upgrade my anti-virus and internet software anyway, so I guess that is what I will do tomorrow night.

[Jerry Peck]

Jerry, is your position then that NM cable are not allowed in a return chase under any circumstance?

b

Not in (B) for ducts and plenums, okay with limitations in (C) for stud and joists spaces.

[brianmiller]

I am taking it as that is a duct next to a wall based on what I am reading in the post, but it may not be. :confused:

Jerry, you are correct that the area next to the wall is a return chase , or duct...someone had removed a section of the sheetrock in the return chase exposing the wall studs, which you see in the photo.

So let's assume that the sheetrock is installed back over the exposed wall studs so that the wall cavity/studs are no longer communicating with the return chase and that the NM cable is left, as in the photo, in the return chase. This scenerio violates Section (B)?

b

[Jerry Peck]

Jerry, you are correct that the area next to the wall is a return chase , or duct...someone had removed a section of the sheetrock in the return chase exposing the wall studs, which you see in the photo.

So let's assume that the sheetrock is installed back over the exposed wall studs so that the wall cavity/studs are no longer communicating with the return chase and that the NM cable is left, as in the photo, in the return chase. This scenerio violates Section (B)?

b

Brian,

Yes, than NM cable is a violation ... with or without that drywall repaired.

The intent of the exception for stud and joists spaces is because NM cable will be running through many spaces, and without the exception NM cable would not be allowed in those stud and joists space, or those stud and joist spaces would not be allowed for return air use.

The reason it does not matter if that drywall is repaired or not and it is a violation is because the NM cable not run through the stud space, it runs through the duct ... and that is not allowed. :)

[Garry Blankenship]

The issue is with non-encapsulated conductors, ( no armor jacket or conduit or U/L approved non-flammable protection ), because the off gas of burning insulation on typical conductors like N/M, voice/data cables, most typical conductors etc. is potentially lethal. Hence, you should not run them in a chase providing breathable, ( environmental ), air. The H.I.s job is to tell clients of the potential danger. Citing chapter & verse is up to whomever holds the applicable license or litigants.