# Why no extension cords? **URL:** \ **Category:** Factual Questions\ **Created:** [June 10, 2010, 12:26pm UTC](https://boards.straightdope.com/t/why-no-extension-cords/542640 "2010-06-10T12:26:01Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![Heckity](https://avatars.discourse-cdn.com/v4/letter/h/a5b964/32.png) [@Heckity](https://boards.straightdope.com/u/Heckity)\ **Post date:** [June 10, 2010, 12:26pm UTC](https://boards.straightdope.com/t/why-no-extension-cords/542640/1 "2010-06-10T12:26:01Z")
I’ve just purchased a second 9000 BTU portable air conditioner for my home. This is the sort on wheels that vents out a window by means of an exhaust hose. Unfortunately the electrical outlet and window are no where near one another. There are dire warnings in the manual and on the plug itself that state the unit cannot be used with an extension cord. I would buy the highest grade interior extension cord to use - but the warning that using an extension could result in death, fire, or severe shock is a little unnerving, frankly. I plan on only having the unit plugged in and operating when I’m at home - I don’t plan on cooling space that I’m not using. Of course there is always the option to call an electrician and have a proper wall outlet installed near the window - but that’s a lot more expensive than an extension cord. Are the warnings simply the manufacturer’s due diligence, or is there a legitimate concern about using an extension cord? ---
**Author:** ![Harmonious\_Discord](https://avatars.discourse-cdn.com/v4/letter/h/74df32/32.png) [@Harmonious\_Discord](https://boards.straightdope.com/u/Harmonious_Discord)\ **Post date:** [June 10, 2010, 12:30pm UTC](https://boards.straightdope.com/t/why-no-extension-cords/542640/2 "2010-06-10T12:30:43Z")
You must seek out one made for that special purpose and load. Search for air conditioner extension cord. they do get warm. They are not very long either. Don’t expect to find a 15 foot long one. ---
**Author:** ![Colophon](https://avatars.discourse-cdn.com/v4/letter/c/f05b48/32.png) [@Colophon](https://boards.straightdope.com/u/Colophon)\ **Post date:** [June 10, 2010, 12:31pm UTC](https://boards.straightdope.com/t/why-no-extension-cords/542640/3 "2010-06-10T12:31:24Z")
WAG - the air con unit draws a lot of current, and they want to cover against people using extension cords that come on a reel. If you use those with high-current appliances without unwinding the reel fully, the cable can overheat. I don’t see that there would be any problem with a straightforward extension lead, as long as it was rated to handle the current and was fitted with an appropriate fuse. Edited to add: the important part of course is the current rating - an air-con unit can draw a lot of current. There should be a label on the unit stating what the power requirement is (in watts). You can then work out what current it will draw. ---
**Author:** ![ratatoskK](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/ratatoskk/32/2987_2.png) [@ratatoskK](https://boards.straightdope.com/u/ratatoskK)\ **Post date:** [June 10, 2010, 12:31pm UTC](https://boards.straightdope.com/t/why-no-extension-cords/542640/4 "2010-06-10T12:31:52Z")
I’m sure electricians will chime in shortly, but personally, I think the concern is about the capacity of the wire. If you get a heavy duty extension cord I think it will be fine. ---
**Author:** ![Shark\_Sandwich](https://avatars.discourse-cdn.com/v4/letter/s/f04885/32.png) [@Shark\_Sandwich](https://boards.straightdope.com/u/Shark_Sandwich)\ **Post date:** [June 10, 2010, 12:37pm UTC](https://boards.straightdope.com/t/why-no-extension-cords/542640/5 "2010-06-10T12:37:14Z")
I think it’d mostly due diligence. Some people think an extension cord is an extension cord is an extension cord, and would probably have no problem plugging in a 20 ft, 3 prong lamp cord in as an extension cord, and next thing you know, the cord’s melted and your house is on fire. Like **Harmonious** said, get the highest guage commercial AC cord you can find. Plug it in and run it for an hour or so, and check to see if the cord’s getting hot. ---
**Author:** ![engineer\_comp\_geek](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/engineer_comp_geek/32/504_2.png) [@engineer\_comp\_geek](https://boards.straightdope.com/u/engineer_comp_geek)\ **Post date:** [June 10, 2010, 12:43pm UTC](https://boards.straightdope.com/t/why-no-extension-cords/542640/6 "2010-06-10T12:43:37Z")
You can’t just buy one that says “heavy duty” because there is no formal definition for exactly what “heavy duty” is. Look for one that is rated at 15 amps or is made out of 14 gauge wire. Make sure it makes a nice solid connection at the air conditioner and also where it plugs into the wall. A loose connection in either place could result in a fire. Also make sure that nothing is near the wall outlet that might push the plug loose (like a piece of furniture). ETA: By the way, just to be clear, the WAGs above are correct. The main concern is that you’ll overload the extension cord and cause it to heat up. If you use too small of a rated extension cord then it gets hot, the plastic melts, the wires touch, and bad things happen. ---
**Author:** ![Nava](https://avatars.discourse-cdn.com/v4/letter/n/da6949/32.png) [@Nava](https://boards.straightdope.com/u/Nava)\ **Post date:** [June 10, 2010, 12:53pm UTC](https://boards.straightdope.com/t/why-no-extension-cords/542640/7 "2010-06-10T12:53:49Z")
Also, many people will not just use “an extension cord plugged into the wall, with the A/C unit plugged into the cord”. I’ve seen pileups of as many as four 1-plug-becomes-3 gizmos, with plug bars then plugged into any of the reachable plugs in that mess. “Don’t use extension cords” is clearer and therefore a better defense in a trial than “use only with extension cords rated XYZ Amp or above”, much less explanations on the danger of playing “who can plug more things into a single outlet?” ---
**Author:** ![canadiankorean](https://avatars.discourse-cdn.com/v4/letter/c/2bfe46/32.png) [@canadiankorean](https://boards.straightdope.com/u/canadiankorean)\ **Post date:** [June 10, 2010, 12:57pm UTC](https://boards.straightdope.com/t/why-no-extension-cords/542640/8 "2010-06-10T12:57:20Z")
I should unplug my portable air con… I have it plugged into a surge protector which is plugged into another surge protector… ---
**Author:** ![Finagle](https://avatars.discourse-cdn.com/v4/letter/f/b19c9b/32.png) [@Finagle](https://boards.straightdope.com/u/Finagle)\ **Post date:** [June 10, 2010, 12:59pm UTC](https://boards.straightdope.com/t/why-no-extension-cords/542640/9 "2010-06-10T12:59:01Z")
> [@engineer\_comp\_geek](#): > > You can’t just buy one that says “heavy duty” because there is no formal definition for exactly what “heavy duty” is. Look for one that is rated at 15 amps or is made out of 14 gauge wire. I’d go with a 12 gauge, 20 Amp cord, especially if it’s going to be a longer run. ---
**Author:** ![bouv](https://avatars.discourse-cdn.com/v4/letter/b/bc8723/32.png) [@bouv](https://boards.straightdope.com/u/bouv)\ **Post date:** [June 10, 2010, 1:04pm UTC](https://boards.straightdope.com/t/why-no-extension-cords/542640/10 "2010-06-10T13:04:53Z")
> [@Shark\_Sandwich](#): > > I think it’d mostly due diligence. Some people think an extension cord is an extension cord is an extension cord, and would probably have no problem plugging in a 20 ft, 3 prong lamp cord in as an extension cord, and next thing you know, the cord’s melted and your house is on fire. A 3-prong cord? Hell, most people I know would buy one of those grey ground plug adapters\*, and then plug the AC into one of those teeny, tiny white or brown extension cords that have only two prongs, and for some reason never let you actually plug a plug into them all the way…you know the cords I mean. \*I feel a need to point out that I have neer seen one of those used the proper way. Most people use them as a way to “get rid of” the ground plug so they can plug a 3-prong plug into only a 2-prong outlet, but never take that little ab and screw it into the screw on the outlet faceplate like they shuld…of course, that assumes that it’s a metal outlet box that itself is grounded, which IME isn’t very likely, either. ---
**Author:** ![johnpost](https://avatars.discourse-cdn.com/v4/letter/j/f17d59/32.png) [@johnpost](https://boards.straightdope.com/u/johnpost)\ **Post date:** [June 10, 2010, 1:22pm UTC](https://boards.straightdope.com/t/why-no-extension-cords/542640/11 "2010-06-10T13:22:12Z")
get as short an extension cord as needed, you can find them in 3, 6 or 9 feet. get an extension cord with number 12 wire (and a ground). if the receptacle in the wall doesn’t take the plug solidly without wiggle then it should be replaced. ---
**Author:** ![kferr](https://avatars.discourse-cdn.com/v4/letter/k/71e660/32.png) [@kferr](https://boards.straightdope.com/u/kferr)\ **Post date:** [June 10, 2010, 1:37pm UTC](https://boards.straightdope.com/t/why-no-extension-cords/542640/12 "2010-06-10T13:37:40Z")
> [@Heckity](#): > > Of course there is always the option to call an electrician and have a proper wall outlet installed near the window - but that’s a lot more expensive than an extension cord. Or have an electrician replace the short cord on the AC with a longer one of the right type. ---
**Author:** ![ftg](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/ftg/32/2801_2.png) [@ftg](https://boards.straightdope.com/u/ftg)\ **Post date:** [June 10, 2010, 1:46pm UTC](https://boards.straightdope.com/t/why-no-extension-cords/542640/13 "2010-06-10T13:46:29Z")
It is _not_ just an issue with the cord failing. Extension cords on motor-based devices (and an AC is very definitely one of those) impair the smooth running of the motor. From [here](http://www.appliance411.com/links/Helpful_Tips/Air_Conditioner/): “Do not operate the unit on an extension cord! The compressor draws a lot of current and can be damaged if insufficient voltage is continually supplied. If you must use one, use only those designed for air conditioners (usually flat) AND only as long as required. NEVER use a lawn mower extension cord.” There is a lot weird stuff that involves motors, phase shifts and voltage drops that’s involved. Especially during startup when the load is worse. It’s one thing to fry an extension cord. It’s another thing to fry the AC unit. ---
**Author:** ![Qwakkeddup](https://avatars.discourse-cdn.com/v4/letter/q/90ced4/32.png) [@Qwakkeddup](https://boards.straightdope.com/u/Qwakkeddup)\ **Post date:** [June 10, 2010, 2:25pm UTC](https://boards.straightdope.com/t/why-no-extension-cords/542640/14 "2010-06-10T14:25:49Z")
> [@kferr](#): > > Or have an electrician replace the short cord on the AC with a longer one of the right type. This here gets my vote. Real power tool, heavy gauge extension cords are expensive and it would probably cost about the same. Less connections, less potential for problems. ---
**Author:** ![FluffyBob](https://avatars.discourse-cdn.com/v4/letter/f/ecb155/32.png) [@FluffyBob](https://boards.straightdope.com/u/FluffyBob)\ **Post date:** [June 10, 2010, 3:15pm UTC](https://boards.straightdope.com/t/why-no-extension-cords/542640/15 "2010-06-10T15:15:54Z")
You can certainly find even 10 gauge cords, I have a couple I use for compressors. A little extra copper never hurt anyone. Re-wiring it with a new cord is probably pretty simple, internal connection is quite likely a stress relief and murettes. You can get bulk cable at a hardware store, just use a nice heavy gauge, house supply is done with 8 gauge so that should be plenty. I had to run a 50 ft extension for a construction heater. Talked to my electrician, and made it myself. Fifty feet of 8/4 exterior cable (240v appliance), male and female ends and a couple 240 junctions ran me about $270. ---
**Author:** ![Cat\_Whisperer](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/cat_whisperer/32/4839_2.png) [@Cat\_Whisperer](https://boards.straightdope.com/u/Cat_Whisperer)\ **Post date:** [June 10, 2010, 3:26pm UTC](https://boards.straightdope.com/t/why-no-extension-cords/542640/16 "2010-06-10T15:26:41Z")
Threads like this are one of the reasons that not being able to have medical and legal advice threads here are such crap - we can give her advice on how to burn her house down, but not what that mole is. Get an electrician to do a proper job, either on the cord on installing an outlet - you don’t burn your $150,000 house down over a $80 electrician charge. ---
**Author:** ![johnpost](https://avatars.discourse-cdn.com/v4/letter/j/f17d59/32.png) [@johnpost](https://boards.straightdope.com/u/johnpost)\ **Post date:** [June 10, 2010, 3:46pm UTC](https://boards.straightdope.com/t/why-no-extension-cords/542640/17 "2010-06-10T15:46:46Z")
need to have a country perspective 20A for an air conditioner would be 12AWG. current standards in the USA would be to have an air conditioner as the only load on a 20A circuit. flat cord as an extension cord or a replacement cord would be best. a person could make an extension cord or put in a replacement cord though this has to be done with good electrical practice. replacement cord would likely be done with terminals on a terminal strip in the USA, you would also need the replacement cord fit in the hole provided and have adequate strain relief (this might be custom work to duplicate the factory cord situation). ---
**Author:** ![ookpik](https://avatars.discourse-cdn.com/v4/letter/o/c68b51/32.png) [@ookpik](https://boards.straightdope.com/u/ookpik)\ **Post date:** [June 10, 2010, 4:19pm UTC](https://boards.straightdope.com/t/why-no-extension-cords/542640/18 "2010-06-10T16:19:44Z")
I run into this situation all the time in IT. Forget the extension cords and the possibility of causing a fire. Instead, get yourself a proper power bar with a longer than normal cord. I’ve picked them up with 9 and 12 foot lengths. Spend some $$ on it, don’t go for a cheap one. Don’t get one at a dollar either. ---
**Author:** ![StinkyBurrito](https://avatars.discourse-cdn.com/v4/letter/s/b9e5f3/32.png) [@StinkyBurrito](https://boards.straightdope.com/u/StinkyBurrito)\ **Post date:** [June 10, 2010, 4:58pm UTC](https://boards.straightdope.com/t/why-no-extension-cords/542640/19 "2010-06-10T16:58:20Z")
I see two things to worry about, amps and volts. The longer the cord run, the bigger the voltage drop is going to be, so use the shortest path possible. So you wouldn’t want to use a 100’ lawn mower extension cord on a spool or something. The bigger issue is amps. Too many amps through too small of a wire will cause heating and potentially fire. There is really not that much difference between 14awg Romex and 14awg extension cord. You mentioned running romex behind the wall to create a new outlet that the AC would then plug into. Running a similarly sized extension cord is basically the same thing. The ends are not as secure, so special attention would need to be paid to the connection. And you wouldn’t want to wind up the cord, or run it under rugs, or run it through an adapter of any sort etc. However, I am not an electrician, and I advise you follow the proper precautions set forth my the manufacturer and the building codes where you live. ---
**Author:** ![JoeH2O](https://avatars.discourse-cdn.com/v4/letter/j/9de053/32.png) [@JoeH2O](https://boards.straightdope.com/u/JoeH2O)\ **Post date:** [June 10, 2010, 5:02pm UTC](https://boards.straightdope.com/t/why-no-extension-cords/542640/20 "2010-06-10T17:02:38Z")
The nature of what you put on that extension is also a concern - I have seen people using extension cords here in the UK to power high-current devices simultaneously - increasing the current drawn through the extension cord to dangerous levels. If you do extend it (and I seriously advise talking to an electrician if you are at all unsure about any steps or a safe setup) then never connect anything else to that cord. To make doubly sure no one else does either, if the extension has more than one socket cover the other ones over securely with duct tape or fill them with epoxy. My personal preference for an AC unit in the states would be to have a dedicated circuit put in by an electrician that goes back to the breaker with decent plugs. US-style outlets and plugs scare the crap out of me and I would not trust a semi-permanent fixture drawing that much load based on the domestic outlets I have seen. I grew up with UK outlets though - the nuclear option as far as outlet design goes. [Next page](https://boards.straightdope.com/t/why-no-extension-cords/542640.md?page=2)