I'm living in an old apartment, and my roommate has fed electrical cords through a heating vent from the living room into the bathroom, up to a power bar on the side of the sink. I see this as a double hazard and illegal.

The heating vent exits from the wall behind the toilet, about 3 inches off floor. He says it is safe because the power bar and the cords behind the toilet will not cause a fire because the heat in the vent will dry any condensation that might cause an electric fire. But wouldn't using an active vent be dangerous, as well as being near water?

I know very little about any of this, but doubt any amount of safety or grounding will make this safe. Would anyone know how to make this situation safer? Or give me some peace of mind so I can sleep.


This roommate is a contractor and is educated through college for home renovations. I cannot convince him to remove this hazard and will move out soon. I was told I was overreacting and do not understand how it works...so I appreciate the confirmation that it is dumb and dangerous.

  • 10
    GFCI protected outlets exist in bathrooms for your protection, and it is explicitly against code to run wire through HVAC systems. You are creating a dangerous situation that at the very least your roommate could end up getting you evicted if your landlord would find out. Do not do this. Commented Dec 10, 2012 at 12:33
  • What? No outlets in the living room? Or is he just too cheap to buy longer extension cords?
    – bcworkz
    Commented Dec 11, 2012 at 5:40
  • Move out. You are not compatible and this will only be the first thing that gets between you. That guy is not going to change his behavior based on advice you got on the Internet. He probably drives with one hand, too.
    – Tim Quinn
    Commented Dec 11, 2012 at 11:02
  • 4
    "This roommate is a contractor and is educated through college for home renovations." That certainly helps explain why it's so hard to find competent contractors.
    – jamietre
    Commented Dec 11, 2012 at 11:13
  • 3
    Suggest to your roommate that you have a county/state electrical inspector come out and look at his work. He should have no problem with that, if it's so perfectly safe. Commented Dec 11, 2012 at 18:27

5 Answers 5


Any electrical socket in a bathroom must have GFCI protection. You're damp, you touch something with a ground fault, feel a slight tickle and wake up wearing a halo and wings. Of all places to hack together power supplies, a bathroom is absolutely the worst place to do this. Mystical theories about the heater protecting the strip from dampness don't remove the shock hazard.

Fire hazard is not your problem here

  • 1
    I agree, this is the worst idea he could come up with. You tell him that you use the bathroom too and to get those things out of there as you don't want to end up as a Darwin Award.
    – GdD
    Commented Dec 10, 2012 at 11:12

I don't know your location, but in the USA, it is strictly forbidden to run any electrical wiring through heating vents or any air handling plenum. The reason for this is that you now have a combustible material in the plenum, that can spread a fire between rooms and into wall cavities. As previously mentioned, any AC electrical outlets in a bathroom MUST be GFIC protected. If you do not have electrical outlets with GFI protection in your bathroom, take it up with your landlord and ask that a safe source of electricity be installed. Meanwhile, get that extension cord/plug strip out of there.

  • 5
    More importantly, PVC insulation which is what's used on most electrical wiring creates a deadly smoke. You do not want that in your HVAC ducting. Not sure if it's still code, but in commercial settings, all low power data cables that were routed through air intakes had to be plenum rated with teflon/tefzel non-flammable insulation. Mains power? Never! Commented Dec 10, 2012 at 16:04
  • @FiascoLabs -- yeah, non-metallic jacketed power cable/cord and air handling spaces don't mix at all -- in commercial work, the only cable that's used in such jobs is type MC, and even then, I suspect that you'd want a different wire type inside it than ordinary THHN... Commented Apr 11, 2015 at 18:12

It's not safe and not good practice to run anything through heat vents. Why can't he use the electricity in the bathroom?

  • There probably isn't any useable outlets in the bathroom - a lot of older houses simply don't have any. My bathroom has plugs built into the light fixture, but that's a big pain. I just deal with it, myself. Commented Dec 11, 2012 at 12:28
  • 1
    What makes it not safe? Why isn't it good practice?
    – Tester101
    Commented Dec 11, 2012 at 20:39

You can reduce the risk of electric shock due to a ground fault (e.g. caused by moisture) using one of these GFCI plugs. Since it sounds like the extension cord starts in the living room, you would use it at the outlet there. It will protect anything downstream the same way a GFCI outlet would. However, this is not a fantastic solution and doesn't solve the issue of the HVAC vent.

Obviously the best solution is to remove the power strip and/or find another place to live.


Your roommate is an idiot who needs to be soundly bludgeoned over the head with a paper copy of the NEC until he gets electrical safety drilled into his thick skull.

Tell him that the county electrical inspector will ask him if he's wearing a halo and wings already until he corrects the violations of 210.8(A):

(A) Dwelling Units. All 125-volt, single-phase, 15- and 20-ampere receptacles installed in the locations specified in 210.8(A)(1) through (10) shall have ground-fault circuit-interrupter protection for personnel.

(1) Bathrooms


(B) Ducts Specifically Fabricated for Environmental Air. Equipment, devices, and the wiring methods specified in this section shall be permitted within such ducts only if necessary for the direct action upon, or sensing of, the contained air. Where equipment or devices are installed and illumination is necessary to facilitate maintenance and repair, enclosed gasketed-type luminaires shall be permitted.

Only wiring methods consisting of Type MI cable without an overall nonmetallic covering, 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 shall be installed in ducts specifically fabricated to transport environmental air. Flexible metal conduit shall be permitted, in lengths not to exceed 1.2 m (4 ft), to connect physically adjustable equipment and devices permitted to be in these fabricated ducts. The connectors used with flexible metal conduit shall effectively close any openings in the connection.

and, of course, 400.8:

400.8 Uses Not Permitted. Unless specifically permitted in 400.7, flexible cords and cables shall not be used for the following:

(1) As a substitute for the fixed wiring of a structure

(2) Where run through holes in walls, structural ceilings, suspended ceilings, dropped ceilings, or floors

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