I have a 2-storey half duplex that was built in 2008. The kitchen (1st floor) has a range hood fan that exhausts to the side of the house through 8" aluminum duct. The outside vent is not directly above the wall where the range hood is, but on a wall perpendicular to it. The vent duct goes up, then right, then right again and then out, about 4 or so meters total. Walls are drywall.

My question is whether I can retrofit an external vent (link below) as the current hood fan is very loud. There is no electrical anywhere around the outlet where the external fan would have to go. The question is whether running the wiring from the kitchen through the aluminum duct is a crazy idea?

I'm thinking that if I insulate the wire properly and bundle it up I can send it through the aluminum duct to the outside fan. Would this pose any risks?

This is the external vent I'm looking to use.

enter image description here

  • 1
    You might find this Answer useful.
    – Tester101
    Jun 4, 2012 at 20:02
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    Would you consider just replacing the fan hood with one that is less noise? Noise is measured in Sones and vent fans all have that as a rating. Generally the cheaper the fan, the noisier it is, and builders will put in the cheapest fans unless you specifically pay for the upgrades.
    – gregmac
    Jun 4, 2012 at 22:03
  • @gregmac: I've considered that as well. I just wanted to explore this possibility as it could virtually deliver pretty decent suction for under 1sone. I currently have a NuTone 810CFM 65dB (~5 sones) and it only has 3 speeds all of which are pretty loud (I would say over 50 dB). I've looked at other options, but I haven't found something at around the same CFM level but with less noise.. Any specific recommendations?
    – 0x6A75616E
    Jun 5, 2012 at 0:36

1 Answer 1


Running the wiring inside the duct work would be a code violation. The grease and oil in the duct will not be kind to the insulation and if a grease fire in the duct next will be an electrical fire not a good idea. Run the wiring along the outside of the duct.

  • Yeah, NEC 300.22 applies here, and this application, while technically not within the scope of 300.22(A), is close enough in nature to it that I'd be very uncomfortable with even a conduit job inside the duct... Feb 17, 2020 at 21:43

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