A new garage door and opener will be installed this week. The opener has a short cord. The outlet is on the wall rather than in the ceiling. This is typical of my area for 1970s construction. The installer said he would install and test on an extension cord, but once he left he would unplug it and the rest was my problem.

I would like to install a longer cord to the garage door opener. This is how the current one is wired. Is this safe?

How do I appropriately select the cord wire gauge? Can I just get a heavy gauge extension cord, cut one end, and hook it up?

The new opener is a LiftMaster. It is one of the manufacturers making like 10 different brands of opener.

I frequently post about electrical issues. I have early aluminum wiring in my home which always adds cost and complexity to any electrical project. In this case I do not think this is relevant as the existing wall outlet is wired safely and correctly. I just need to get from that outlet up to the ceiling and over to the opener.

My goal is to have that cord wired in for a few months while I save up to have the entire garage rewired. I want more lights and more outlets in the entire space. I am looking for a longer-term but still temporary solution.

  • 1
    lol your whole house isn't grandfathered to 1970 electrical code. Anything you do that's new needs to be to code on the day you do it. Apr 22, 2019 at 13:40

2 Answers 2


Both an extension cord and a properly-installed replacement cord (possible built from an extension cord) are viable, temporary solutions in my experienced but unlicensed opinion. You will not overload a 14 gauge cord with a typical 1/3 or 1/2 hp opener. (I'd avoid the lighter 16 gauge cords even if your current plug cord is 16 gauge--you're adding length.)

These solutions will probably not meet building code and will not have UL approval. If it was my home, I'd disregard those things in your situation.

In either case, secure the cord such that it's not likely to be damaged. That's the primary concern with exposed wiring of any kind.


Why can't you install a proper receptacle near the opener? If you don't want to fish cable through the wall/ceiling, you could use conduit run along the surface of the wall/ceiling.

Installing a replacement cord on the opener likely voids the warranty, and UL listing of the opener. Using a cord in this manner is also a code violation (according to National Electrical Code). If you were to ignore UL and NEC, it's probably a good idea to protect the cord from damage (especially in a garage). So rather than pulling a flexible cord through conduit up to the opener, why not just pull three 14 AWG THHN conductors through instead?

  • I have a surface mount outlet with AL wiring. To properly wire conduit I have to 0) figure out what the circuit can handle 1) transition from in-wall to surface mount 2) properly join AL to CU wire 3) run conduit 4) install a box and outlet . Its not an insurmountable project but it would extend the garage door project out. If I have to run new outlets I'd prefer to do it as a whole-garage project rather than a one-outlet project
    – Freiheit
    Jul 20, 2016 at 19:07
  • Oh and good point on the warranty. I'll have to get my hands on the opener to see how it supports different cord attachments. The maker sells a 6' cord as a distinct part with spade end connections, probably voids the warranty if its not their branded cord.
    – Freiheit
    Jul 20, 2016 at 19:20
  • The connections and the strain relief are probably reusable if you're careful. Yeah, good point on the warranty, but it's a low-risk concern in my book. I'd still do it.
    – isherwood
    Jul 20, 2016 at 19:27
  • @Freiheit this is one of those things that I'd do temporarily in my own garage, but I'd never recommend anybody else do.
    – Tester101
    Jul 20, 2016 at 21:30
  • Current plan is to run the extension cord for about 2 weeks and get my electrician out to run a new circuit to the garage. The lone outlet is on the same circuit as the kitchen and dining room. I need more power!
    – Freiheit
    Jul 21, 2016 at 3:01

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