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I recently learned (via a rant from an electrician's son and some internet research) that the standard buy-anywhere cheapo extension cords are a big cause of electrical fires and are not recommended to be left plugged in.

So say I DO want to leave an extension cord plugged in permanently around the house. Is there some type of cord or some feature of a cord that is safer for this?

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  • So long as you only use them temporarily (while you own the house), and not permanently (until the Sun swells up and engulfs the Earth, you're fine. Make sure they are rated to handle the current needed, and don't damage them. Also, consider using a power strip with a long cord. It will do the same thing, with a fancy lighted switch on one end, and since its "not an extension cord" it doesn't get the same scrutiny.
    – Billy left SE for Codidact
    Jan 7, 2016 at 9:05

3 Answers 3

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Extension cords that are not listed, labeled, or rated for permanent (long term) use are all temporary wiring devices.

If you need to permanently connect an electrical device, you should use approved wires and/or cable assemblies installed in an approved manner.

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    +1 But many of use live in houses (and apartments where changes may be forbidden) which don't meet current code about placement of outlets. Can't we give some guidance on safer use of extensions (even if we resist agreeing that they are permanent).
    – bib
    Nov 27, 2013 at 22:18
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    Any extension cord that is listed and labeled (UL, etc.), should be safe for use. Given it's used in appropriate locations, and is not subject to physical damage.
    – Tester101
    Nov 27, 2013 at 22:20
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    Forgive the layman, but what does it mean to be "listed and labeled"?
    – George Mauer
    Nov 27, 2013 at 23:21
  • @GeorgeMauer Listed, means it's approved for use by local code bodies. Labeled, means it's been tested and certified by a third party testing organization (Underwriters Laboratories for example), and carries their label certifying the product has been tested and is safe for use.
    – Tester101
    Nov 28, 2013 at 0:47
  • sounds like this is US stuff, if so any UK readers need to check if cable has a BSI rating I
    – user47420
    Jan 6, 2016 at 17:27
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The Uniform Fire Code covers extension cords. They are for temporary immediate use of an appliance and are not for permanent installation. The code is not available online but here is a page that references it: http://www.grand.k12.ut.us/district/fire.htm#anchor157315

However, extension cords are different from power strips (AKA Temporary Power Tap) in that power strips with circuit breakers or breaker power switches have built in over-current protection. Power strips may be used for long term installation. Here is a page with more details: http://www.nccu.edu/health-safety/eohs/extensionCordsPowerStrips.cfm

So to answer your question, use a power strip with over-current protection if you need more outlets. Be sure to check as some power strips only have an on/off switch (no over-current protection)

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  • And over-current protected power strips are available with different length cords (3ft - 25ft).
    – Fiasco Labs
    Aug 5, 2014 at 2:02
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As Tester101 says, extension cords are not meant for permanent wiring. If you really need an outlet in a given location, you should consider having one installed.

But there are a number of things to keep in mind when you are using extension cords.

  • Don't staple them in place (big risk of damage)
  • Don't use a cord that is rated for less amperage/wattage than you are using
  • Don't try to use a two wire/two prong cord for a three prong device
  • Don't octopus the cord (adding a multitap adapter at the end of the cord)
  • Avoid using extension cords for any high draw devices, such as refrigerators, toaster ovens, irons, hair dryers, etc.
  • Don't leave exterior cords plugged in

In general, the use of three prong, heavier (wire gauge, not weight), shorter cords are preferable.

And make sure they are out of the way and not a trip hazard (no crossing thresholds, other footpaths).

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    this answer provides a good list of extension cord Don'ts.
    – Tester101
    Nov 28, 2013 at 0:50
  • I think the second point is very important. Even indoors, I only use heavy duty, thick gauge, 3-prong extension cords. Cheap, thin cords can overheat and cause an electrical fire. There are two things I don't mess around with and will spend good money on: extension cords, and tires for my car.
    – user4302
    Nov 28, 2013 at 5:50
  • @Tester101 Now that's what I was looking for!
    – bib
    Nov 28, 2013 at 13:10
  • Per our fire marshal no zip cords, ever. Use SJO (jacketed three wire) extension cords. The latest spec is SJOOW (oil resistant jacket and insulation, weather and water resistant).
    – Fiasco Labs
    Aug 5, 2014 at 2:07
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    I would add to this list to never use an extension cord when still coiled up. The rating assumes the cord will cool in open air, but coiled-up cords cannot dissipate heat very well, which can lead to a fire.
    – JYelton
    Sep 16, 2014 at 1:53

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