I have a lack of plugs outside my house and was wondering if it's okay to run an extension cord through my crawl space (from the garage, underneath my living room and through a crawlspace vent).

Edit I'm looking to add power outside for Christmas lights/ low voltage outdoor walkway lighting.

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    Why not just do it right? – Tester101 Aug 21 '12 at 17:11
  • What kind of loads are you looking at? It wouldn't be too hard to run a proper outlet. If you're comfortable with wiring, It could even be a DIY project. – Chris Cudmore Aug 21 '12 at 18:54
  • Thanks for all the great answers, as suggested I'm going to run a new outlet off an existing one. – christo16 Aug 22 '12 at 16:03
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    Absolutely not. Does not pass fire inspection or code. If your insurance company figures out it caused a fire, you may lose rights to compensation for property damage. – Fiasco Labs Oct 25 '14 at 22:28

Would it be to code and pass a city inspection? I highly doubt it, particularly because it is through a vent and there are specific code requirements for running electrical cables in that scenario.

Will it work? Yes.

I'd say if its for a short-term/temporary measure of light loads (a light) it will be OK, but if you plan on it being permanent or running heavy loads (an electric lawn mower), you should really have a new water tight outlet properly installed.

  • 2
    The gauge of the cord would also have to be taken into account. – Tester101 Aug 21 '12 at 17:08

I don't see anything fundamentally wrong with that approach on a temporary basis, just be sure to follow typical safety guidelines about extension cords. Use an appropriately sized, grounded, outdoor extension cord. Consider GFCI protection.

Extension cord safety

Sizing extension cords at about.com

Safety groups generally caution against using extension cords in a permanent capacity, or installing inside ceilings, crawlspaces, etc. I presume the primary underlying concern is about routing and protection of the cable to prevent damage. You may have critter-damage concerns in your application.

If you've got such easy access to the crawlspace, what about running a new circuit, or an extension of an existing one, to create that outlet you desire?

  • Do you have a good starting point for adding another circuit? Might need to have an electrician do that though :| – christo16 Aug 21 '12 at 18:15

Here's how I'd do it.

  1. Find an outlet in the basement near your crawlspace that isn't part of a heavily loaded circuit.
  2. Turn off the circuit!
  3. Replace this outlet with a GFCI.
  4. Run a 14/2 wire from the LOAD of the GFCI through the crawlspace to the wall where you want it to go. (Securing it to joists where appropriate)
  5. Drill a hole through the wall.
  6. Mount an appropriate box with covers to the outside over the hole. (I prefer metal).
  7. Run the cable through the hole, and fill the hole with as much caulk as you can get in there. (Or see comments for other ideas on sealing)

  8. Wire up the new outlet, and mount it in the box.

  9. Turn circuit back on.
  10. Profit.

Now, some of these steps are non-trivial, but a little research on this site will get you going.

I've got a similar outlet wired off of my workbench supply, working on the theory that I won't be running electric motors outside and at the bench at the the same time.

  • 1
    Use a Weatherproof box, PCV Conduit (with appropriate fittings) through the wall, and an In-use Cover. No caulk needed – Tester101 Aug 21 '12 at 19:20
  • 1
    Duct Seal works great for sealing around conduit. – Tester101 Aug 21 '12 at 19:31
  • This is a good idea, I'm planning on using it for Christmas lights/low voltage outdoor lighting. Think it will be okay? – christo16 Aug 22 '12 at 0:27
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    +1 Since it's for outdoor lighting, I would recommend the "in-use" outlet cover so the wiring can remain plugged in. – BMitch Aug 22 '12 at 1:18
  • @Christo16 This should work out well enough. The major worry is overloading a circuit. LED Christmas lights are pretty low draw, so taking a feed off an existing circuit is probably ok. If you plan to go big, then you should get an electrician in to wire up a subpanel in the basement that you could take feeds off of. – Chris Cudmore Aug 22 '12 at 12:50

I'd advise against it, even for a temporary install, because these kinds of things (where it's annoying to get in and pull it back out) tend to become semi-permanent, and that's dangerous.

Given that it's a crawlspace, I'd agree with other posters and say put in a real outlet and call it a day.


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