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#59989 - 12/20/05 02:38 PM Inside A Chimney Chase  
Old Town  Offline
Joined: Nov 2005
Posts: 21
Dallas,TX USA
I need to run a 120V receptacle circuit and a 3/4" stub up for low voltage down a chimney space. They (the owner) say the chimney is built with double wall flue with 8-10" airspace, and then then the two courses of brick. I have no idea what the ambient temp would be in this chase. Sounds easy enough. Has anyone here ever done this? I have seen receptacles on masonary hearths but they were all new construction, never old work.

Thanks in advance.


[This message has been edited by Old Town (edited 12-20-2005).]

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#59990 - 12/20/05 02:41 PM Re: Inside A Chimney Chase  
SvenNYC  Offline
Joined: Aug 2002
Posts: 1,691
New York City
*text removed by original poster -- wrong thread*

[This message has been edited by SvenNYC (edited 12-20-2005).]

#59991 - 12/20/05 03:01 PM Re: Inside A Chimney Chase  
jwhite  Offline
Joined: Dec 2005
Posts: 64
Trenton, NC, USA
are you talking about between the flue and the brick? My guess is that it would be hot.

#59992 - 12/20/05 03:22 PM Re: Inside A Chimney Chase  
Old Town  Offline
Joined: Nov 2005
Posts: 21
Dallas,TX USA
Yes, it will be between the flue and the brick. I am starting to wonder if I want to do this one or not. I don't think the ambient temp will really get that hot, but I am not sure.

#59993 - 12/20/05 03:47 PM Re: Inside A Chimney Chase  
gfretwell  Offline

Joined: Jul 2004
Posts: 9,140
I don't think you have enough information to make an informed decision. If there is no draft stopping and ambient air can follow the conduit up the chimney space I would not expect much temperature rise but if this is only open at the top your mileage will vary, based on how much makeup air could displace the hot air that exits.
It may not get hot enough to support combustion but you have to start derating at 86f/30c.
At a combined temp (ambient plus I2R heating) of 90c/194f your THHN insulation may start failing.

Greg Fretwell

#59994 - 12/20/05 08:00 PM Re: Inside A Chimney Chase  
renosteinke  Offline
Cat Servant
Joined: Jan 2005
Posts: 5,316
Blue Collar Country
I'm not sure, but it seems to me that putting anything in that air-space would violate the fire code. I think that space must be kept absolutely clear.

#59995 - 12/20/05 08:35 PM Re: Inside A Chimney Chase  
ShockMe77  Offline
Joined: Jun 2005
Posts: 821
Rahway, New Jersey
I have never run any type wire on the inside of a chimney.


#59996 - 12/20/05 10:34 PM Re: Inside A Chimney Chase  
Old Town  Offline
Joined: Nov 2005
Posts: 21
Dallas,TX USA

I removed a brick above the mantle and I found this:
Behind the brick , a 2 1/2" space between the brick and sheetrock. Behind the sheetrock is an additional 8" and then a double flue setup. I can easily run flex behind the brick. What do y'all think. Thanks in advance.


#59997 - 12/21/05 01:45 AM Re: Inside A Chimney Chase  
DougW  Offline
Joined: Jun 2003
Posts: 1,143
North Chicago, IL
[fallback answer] Check with your AHJ [/fallback answer]

I have no idea how hot it would get in there, but I'd consider using 90 degree C wire instead of 75.

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