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Old 12-30-2009, 08:19 AM   #1
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EMT on chimmeny wall?

Hello and Happy New Year to all.
We are taking out all the Knob & Tube in a 106 year old house we just bought and replacing it all with MC & Romex as code requires. It looks like the easiest way to rewire the second floor is to come down from the attic. (Note: the attic is accessed via prement stair and has hardwood floor) It looks like the best route for the new wiring is straight up the side of the chimmeny. The chimmeny only services one 19 year old boiler which enters from the opposite side we want to come up. My question is, is it legal to run EMT up this opening and run wiring to a sub-panel to feed the second floor and attic?


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Old 12-30-2009, 10:18 AM   #2
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There are different types of chimney. Some are brick and do not get hot on the outside and the wood framing is right up against the chimney.

Others are metal, they can get hot on the outside, and there is a gap between the chimney and any wood framing.

So that is the question I would have. Does the outside of the chimney get warm/hot? If yes, then I would not run wire next to it.

And I would not drill any holes into a chimney for anchors or supports for the wiring.

As to code, take pictures of the area and go ask your local electrical inspector. These are the guys who will ok your work, so best to ask them ahead of time. In my area they have certain hours where you can go and ask questions.

If a brick chimney, you might want to take a picture on the roof looking down the chimney, if you can safely do this. And measure the thickness of the brick to the inner chimney on the side you want to run the wiring.

Brick has an "R-value" which is its insulating ability. The thicker the brick, the more insulation it would have. I don't know if the inspector would need this information or not, but good to be prepared. Also if you know the BTU's of the furnace, that may be helpful to the inspector as well.

My local building inspector has all these numbers rattling around in his head. He is a walking "R-value calculator"!
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Old 12-30-2009, 10:28 AM   #3
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Originally Posted by Airen View Post
. My question is, is it legal to run EMT up this opening and run wiring to a sub-panel to feed the second floor and attic?
what "opening"?

the only opening involving a chimney I am aware of is the inside the chimney and if you are considering that, then no, it is not legit nor safe. There is the obvious heat plus there are generally acidic gasses that will eat the conduit.

if there is an opening outside of the chimney, then as billy_bob states: if it doesn't get hot, then it should be fine.

it sounds like you might be getting quite extensive here so I would think you might have some walls open. If so, consider running several conduits up an open cavity. One for the panel you need but a couple extra for something missed or future use.

It's really hard to really get too specific because each house is a world in itself but generally, the best avenue is up a wall cavity unless you are willing to accept exposed conduit, which would be either inside or outside the structure.
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Old 12-30-2009, 12:42 PM   #4
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If it is actually 106 years old, then it is probably a masonry chimney since tin chimneys were not around then. - flues possibly.

Just minimize the amount and depth of attachments/Tapcons into the chimney since there probably is very little load on a conduit inside the house.

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Old 12-30-2009, 06:53 PM   #5
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Thank you

Thank you all for your replies. The chimmeny is brick with a clay? flue liner. The joints look quiet good. There is wood framing around the chimmeny at the 1st & 2nd floor, but it does not seem to contact the chimmeny at any point. There is about a 3 inch gap between the chimmeny and the framing. At the roof the framing and flashing do contact all sides. The brick is room temp. and does not feel warm when the boiler is running. I am not sure if it matters, but the chimmeny had an additional boiler, huge thing probably as old as the house which has been removed along with the asbestos and a gas fired water heater. Both are being replaced by new unit mounted on wall and vented through wall. Oh, and it seems I was incorrect about the age, i have been informed that it a 109 years old. ; }

Thanks again


Last edited by Airen; 12-30-2009 at 07:01 PM.
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Old 12-30-2009, 07:03 PM   #6
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code used to require a 2" airspace between outside of masonry to flammables like framing. sounds like what your looking at and i don't know if wires in conduit fall in that category. I agree other paths if available are better
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Old 12-30-2009, 09:57 PM   #7
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106 year old house ? I am pretty sure you may have ballon framed house if that the case it will be straight shot to run the conduit from one of wall cavity all the way from attic to basement.

However expect some fire stop along the way if so the firestop typically useally around 4 feet or mid span between ceiling and floor that is the only quirk otherwise it will be smooth sailing for ya or get close to the vent or drain pipe that useally pretty straght shot as well but how much room and if the drain / vent pipe may have a tee or wye fitting if that case it will block the way you want to bring it down.

So look around the house there are few options you can expore and useized it.

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