# Romex and heat ducts



## handifoot (Feb 19, 2006)

As I'm running 12/2 romex through my basement ceiling I will be encountering metal HVAC warm air ducts. I plan on going over or under these ducts but this means that the wire will come into contact with them.

Is this OK, should I use some type of insulating material or what?


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## HouseHelper (Mar 20, 2007)

Just avoid any sharp edges.


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## chris75 (Aug 25, 2007)

I try to stay under them, this way if you install hardwoods above they wont get damaged.


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## Gencon (Apr 10, 2008)

Romex should be 1" away from the heat ducts. You can slip in a small piece of batt insulation between the wire and the duct.


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## chris75 (Aug 25, 2007)

Gencon said:


> Romex should be 1" away from the heat ducts. You can slip in a small piece of batt insulation between the wire and the duct.



Why 1"?


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## Termite (Apr 13, 2008)

Gencon said:


> Romex should be 1" away from the heat ducts.


Not true. There is no clearance requirement between romex and heat ducts. As mentioned, just watch the sharp edges. 

However, 1" of clearance is required from wires and combustible materials to a B-vent furnace or water heater flue (carries combustion gases and high temps). Clearance must also be maintained between single wall vent flues and fireplace vents.


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## handifoot (Feb 19, 2006)

So, would that 1 inch clearance apply to the yellow flexible natural gas line that runs up to the kitchen?


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## Termite (Apr 13, 2008)

handifoot said:


> So, would that 1 inch clearance apply to the yellow flexible natural gas line that runs up to the kitchen?


No clearance is required between the CSST yellow gas line and household wiring, if that's what you're asking.

The CSST gasline should be kept at least an inch from the furnace and water heater flues that I mentioned earlier, but there's no issue with duct clearance. The hazard with the flues is that they get very hot and could melt the yellow PVC jacket off the gas line. That won't hurt the gas line itself, but the PVC is technically combustible. 

Your normal HVAC ductwork doesn't get hot enough to melt any wiring or CSST gasline.


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## Gencon (Apr 10, 2008)

In some locales now Romex is not allowed to cross the heat ducts at all. They must go around. I havent run into this yet but the standard practice is 1" clearance. Heating ducts can get upwards of 180*f, probably not enough to melt anything but hot none the less.
Supply ducts are required to be 1" away from combustibles such as the joists.If Romex is considered to be a combustible then this rule applies to it as well.


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