Wiring ?

Page 1 of 2  
My house is over 100 years old and the cold air returns are simply sheet metal nailed between two joists.
I know that when running romex though holes bored in the joists according to the National Electrical Code I'd need to run type "MI" if wiring through the cold air return joists.
I was wondering it it would be OK to run conduit across the /outside/ of the return? I know that romex can only be run through holes in the joists.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Friday, July 11, 2014 11:06:36 AM UTC-4, philo  wrote:



s.
I believe standard Romex is permitted to be used through bored holes, just as it would if it were not a return duct. See section 300.22C of NEC where they specifically exempt such spaces between joists. No need to make it more complicated.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Fri, 11 Jul 2014 08:49:30 -0700 (PDT), trader_4

This is the exception Trader is talking about
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.
Even if you do not want to exploit this exception, 300.22 allows these other wiring methods (besides MI)
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.
An easy fix is a short sleeve of EMT between the studs with bushings on the ends and shove your Romex through the sleeve.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On 07/11/2014 11:39 AM, snipped-for-privacy@aol.com wrote:

Thank you both for the replies and helping me wade through the regulations. Now it's time for me to get to work.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

As trader notes below, that is not actually necessary...

Of course it would. It's also OK to run Romex in conduit *through* the return, as long as it's metal conduit.

Not correct. Romex can also be run: * along the face of a joist * stapled to running boards nailed across the bottoms of joists * through conduit attached to the bottoms of joists.

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Or run a large enough conduit through the plenum to be able to call it a "raceway" instead of a conduit - which allows you to run Romex through it. I believe code also allows romex to be run through conduit for "protection"
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Friday, July 11, 2014 1:21:48 PM UTC-4, snipped-for-privacy@snyder.on.ca wrote:
ote:




ts.

He's only got 3 1/2" inches. At some point you start interfering with the air flow.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On 07/11/2014 01:47 PM, jamesgang wrote:

the plenum to be able to call

Well, I went down there the plan my work and saw that one of the cold air returns is double-wide ...so I'd have to remove the sheet metal... plus it's a long run and would require many holes.
I'm just going to run conduit, it's going to be a lot easier.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Friday, July 11, 2014 6:18:39 PM UTC-4, philo  wrote:

the air flow.

Why?
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Fri, 11 Jul 2014 16:40:36 +0000 (UTC), Doug Miller

But NOT if it is inside a plenum. (except in a conduit)

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Fri, 11 Jul 2014 13:21:48 -0400, snipped-for-privacy@snyder.on.ca wrote:

Conduit IS a raceway. (Article 100 Definition)
"Raceway. An enclosed channel of metal or nonmetallic materials designed expressly for holding wires, cables, or busbars, with additional functions as permitted in this Code. Raceways include, but are not limited to, rigid metal conduit, rigid nonmetallic conduit, intermediate metal conduit, liquidtight flexible conduit, flexible metallic tubing, flexible metal conduit, electrical nonmetallic tubing, electrical metallic tubing, underfloor raceways, cellular concrete floor raceways, cellular metal floor raceways, surface raceways, wireways, and busways."
... and this is not a plenum.
"Plenum. A compartment or chamber to which one or more air ducts are connected and that forms part of the air distribution system."
As for the original question,
Trader correctly cited the 300.22(C) exception.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
snipped-for-privacy@snyder.on.ca wrote in

Nobody's talking about a plenum here, just the space between joists which is often enclosed as a cold air return -- and is specifically excepted from those requirements by the section of the Code cited in the paragraph below. (You *did* read that before replying, didn't you?)

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
snipped-for-privacy@snyder.on.ca wrote in wrote:

It doesn't matter at all how large the conduit is, as long as it's large enough for the conductors being run through it. He's perfectly compliant with the NEC running Romex through an air handling space inside 1/2" EMT.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Two points:
1. Just ignore clare; as usual when attempting to give electrical advice, he's well wide of the mark. There simply is no reason at all to think that anything larger than 1/2" EMT is needed.
2. The OP was asking about wiring through a cold air return between *joists*, not studs, so presumably he has at least 7 1/4" to work with (assuming 2x8s).
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

To drill through the center joist of three, obviously.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Friday, July 11, 2014 8:18:05 PM UTC-4, Doug Miller wrote:


Doh! I was just picturing a wider space.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On 07/11/2014 07:32 PM, trader_4 wrote:

yep, three joists.
Anyway, I ended up talking to a friend of mine who is a retired building inspector and he gave me an easy work-around for Romex.
Though I cannot attach it directly to the joists, he said all I have to do is use a "running board" . Basically I just need to run a board across the joists then attach to Romex to that.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Fri, 11 Jul 2014 14:39:00 -0400, snipped-for-privacy@aol.com wrote:

A cold air return comprized of sheet metal nailed to 2 adjacent joists is considered to be a plenum. Air duct #1 connects it to the cold air intake of the furnace. Duct#2 opens to the conditioned living space - it is part of the air distribution system on the return side. Any communication cable installed through such an air return MUST be plenum rated cable by code, so I'm sure power cables would also need to be treeted as "in plenum"
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Friday, July 11, 2014 11:20:56 PM UTC-4, snipped-for-privacy@snyder.on.ca wrote:

wrote:

et


of

ists.

There are none so blind as those that will not see. I gave you the NEC cod e section. Others have discussed it here too. The code says Romex can pass through joists that are part of a cold air return plenum, it's specifically exempted. Plus you see it done all the time. Stop with the misinformation already.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Fri, 11 Jul 2014 18:45:28 +0000 (UTC), Doug Miller

You are right. I thought there was some reference to using romex in conduit where the fill ratio had to be a lot lower than with separate conductors but I've been wrong before. I know there is a fairly broad restriction on running romex in conduit - yet I know there are quite a few situations where it is allowed, and even a few where it is "required" for protection. OK - you don't NEED to use Romex - but if you use romex you DO need to protect it, and conduit is the simlest. cheapest, most effective solution.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Site Timeline

Related Threads

    HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.