# Why did my extension cord melt? **URL:** \ **Category:** Factual Questions\ **Created:** [May 22, 2004, 9:03pm UTC](https://boards.straightdope.com/t/why-did-my-extension-cord-melt/246572 "2004-05-22T21:03:14Z")\ **Posts on this page:** 20\ **Page:** 2
**Author:** ![Colibri](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/colibri/32/1841_2.png) [@Colibri](https://boards.straightdope.com/u/Colibri)\ **Post date:** [May 22, 2004, 10:01pm UTC](https://boards.straightdope.com/t/why-did-my-extension-cord-melt/246572/21 "2004-05-22T22:01:30Z")
> [@EvilGhandi](#): > > Colibri, another question would be, is the cord melted along one conducter or both? The wire should have two channels, one will be smooth the other will have ridges on it. Is one half more heat damaged than the other? Yes, the ridged side is definitely much more damaged along most of its length than the smooth side, although there is some melting evident on the smooth side as well. ---
**Author:** ![Colibri](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/colibri/32/1841_2.png) [@Colibri](https://boards.straightdope.com/u/Colibri)\ **Post date:** [May 22, 2004, 10:05pm UTC](https://boards.straightdope.com/t/why-did-my-extension-cord-melt/246572/22 "2004-05-22T22:05:52Z")
> [@danceswithcats](#): > > Viewing the cord, are there or is there a site on the cord which exhibits localized blackening? This site should be accompanied by visible breaks in the insulation. > :curious: The whole cord is so melted and damaged that nothing is obvious. It is melted all the way through in a couple of places. ---
**Author:** ![Q.E.D](https://avatars.discourse-cdn.com/v4/letter/q/51bf81/32.png) [@Q.E.D](https://boards.straightdope.com/u/Q.E.D)\ **Post date:** [May 22, 2004, 10:08pm UTC](https://boards.straightdope.com/t/why-did-my-extension-cord-melt/246572/23 "2004-05-22T22:08:23Z")
> [@Colibri](#): > > The whole cord is so melted and damaged that nothing is obvious. It is melted all the way through in a couple of places. I’d be interested in actually running some tests on this cord. If you feel like sending it to me, email me. I’m pretty sure you can forgo the postal insurance. 😃 ---
**Author:** ![EvilGhandi](https://avatars.discourse-cdn.com/v4/letter/e/f17d59/32.png) [@EvilGhandi](https://boards.straightdope.com/u/EvilGhandi)\ **Post date:** [May 22, 2004, 10:09pm UTC](https://boards.straightdope.com/t/why-did-my-extension-cord-melt/246572/24 "2004-05-22T22:09:23Z")
posted by QED, " If you got a transformer question, I’m the guy to ask. " Yep, and I did. I noticed you DWC, and Cornflakes in this thread, all posters who’s opinions I regard highly. ---
**Author:** ![EvilGhandi](https://avatars.discourse-cdn.com/v4/letter/e/f17d59/32.png) [@EvilGhandi](https://boards.straightdope.com/u/EvilGhandi)\ **Post date:** [May 22, 2004, 10:18pm UTC](https://boards.straightdope.com/t/why-did-my-extension-cord-melt/246572/25 "2004-05-22T22:18:19Z")
Colibri Post, "Yes, the ridged side is definitely much more damaged " Guys, the wire was damaged down the neutral, which means what? ---
**Author:** ![scotandrsn](https://avatars.discourse-cdn.com/v4/letter/s/a4c791/32.png) [@scotandrsn](https://boards.straightdope.com/u/scotandrsn)\ **Post date:** [May 22, 2004, 10:46pm UTC](https://boards.straightdope.com/t/why-did-my-extension-cord-melt/246572/26 "2004-05-22T22:46:07Z")
I can only wonder at the possibility of a power _surge_ from the aforementioned unreliable power plants. Anyone who live near you report any similar goings on? ---
**Author:** ![Crafter\_Man](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/crafter_man/32/458_2.png) [@Crafter\_Man](https://boards.straightdope.com/u/Crafter_Man)\ **Post date:** [May 22, 2004, 11:20pm UTC](https://boards.straightdope.com/t/why-did-my-extension-cord-melt/246572/27 "2004-05-22T23:20:48Z")
> [@EvilGhandi](#): > > Colibri Post, > > "Yes, the ridged side is definitely much more damaged " > > Guys, the wire was damaged down the neutral, which means what? If only one conductor showed signs of overheating, I would expect it to be the _hot_ conductor, not the neutral. It would also mean that the over-current situation was caused by a ground fault. If the entire length of the extension cord was cooked, then it obviously means there was too much current on the wire. A short (or near short) must have occurred somewhere close to the load. Here are the possibilities: 1. Short inside the receptacle at the end of the extension cord. 2. Short in one of the appliances (though I would expect the appliance cord to also be damaged). 3. Short between hot (at the receptacle) and earth ground. 4. A hot wire in an appliance shorted to earth ground. It is interesting the breaker didn’t blow. Why is that? **Q.E.D.** offered one theory: Assuming there’s a 20 amp breaker, there was enough resistance in the short + extension cord that it “only” pulled somewhere between 16 and 20 amps. Or it could have been higher than 20 amps… at 25 amps (for example), a 20 amp breaker will not immediately trip. It will usually take a few minutes. Or the breaker is bad or frozen up, which is a very good possibility. ---
**Author:** ![Rick](https://avatars.discourse-cdn.com/v4/letter/r/9f8e36/32.png) [@Rick](https://boards.straightdope.com/u/Rick)\ **Post date:** [May 22, 2004, 11:22pm UTC](https://boards.straightdope.com/t/why-did-my-extension-cord-melt/246572/28 "2004-05-22T23:22:17Z")
Any chance you have mice or rats? I have seen rats eat (and cause shorts) in cars many times. Does the damage start from one point and work it way back to the wall plug? If so look at where the damage starts for little tiny teeth marks. ---
**Author:** ![danceswithcats](https://avatars.discourse-cdn.com/v4/letter/d/9e8a1a/32.png) [@danceswithcats](https://boards.straightdope.com/u/danceswithcats)\ **Post date:** [May 22, 2004, 11:25pm UTC](https://boards.straightdope.com/t/why-did-my-extension-cord-melt/246572/29 "2004-05-22T23:25:57Z")
> [@Q.E.D.](#): > > I’d be interested in actually running some tests on this cord. If you feel like sending it to me, email me. I’m pretty sure you can forgo the postal insurance. 😃 Please post your findings, **Q.E.D.** or at least send me an email regarding what you’ve found-digital pictures, too. I’ll share with IAEI and fire service associates. Thanks. ---
**Author:** ![Omphaloskeptic](https://avatars.discourse-cdn.com/v4/letter/o/bcef8e/32.png) [@Omphaloskeptic](https://boards.straightdope.com/u/Omphaloskeptic)\ **Post date:** [May 22, 2004, 11:26pm UTC](https://boards.straightdope.com/t/why-did-my-extension-cord-melt/246572/30 "2004-05-22T23:26:49Z")
> [@Colibri](#): > > It happened while I was out of the house. Fortunately my cleaning lady, who comes once every two weeks, happened to be there. She smelled smoke while she was in another room, and came out to find the rug smoldering under the cord. Luckily for her the circuit breaker seems to have kicked in before she started to do anything about it, or else I don’t like to think what could have happened. When I came home, after she had left, I found she had taken the melted cord from the socket, and left it on a newspaper. There were scorch marks on the rug. I found out what happened after calling her. Is it possible that the cleaning lady had something else plugged in to the extension cord at the time? It seems pretty coincidental for the cord to have melted during the .5% of the time that the cleaning lady is there, otherwise. ---
**Author:** ![Colibri](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/colibri/32/1841_2.png) [@Colibri](https://boards.straightdope.com/u/Colibri)\ **Post date:** [May 22, 2004, 11:30pm UTC](https://boards.straightdope.com/t/why-did-my-extension-cord-melt/246572/31 "2004-05-22T23:30:56Z")
> [@Rick](#): > > Any chance you have mice or rats? I have seen rats eat (and cause shorts) in cars many times. Does the damage start from one point and work it way back to the wall plug? If so look at where the damage starts for little tiny teeth marks. No, I’ve never had any. I’m sure that’s not the problem. ---
**Author:** ![Q.E.D](https://avatars.discourse-cdn.com/v4/letter/q/51bf81/32.png) [@Q.E.D](https://boards.straightdope.com/u/Q.E.D)\ **Post date:** [May 22, 2004, 11:31pm UTC](https://boards.straightdope.com/t/why-did-my-extension-cord-melt/246572/32 "2004-05-22T23:31:00Z")
> [@Crafter\_Man](#): > > If only one conductor showed signs of overheating, I would expect it to be the _hot_ conductor, not the neutral. It would also mean that the over-current situation was caused by a ground fault. Of course, we could have a reversed hot and neutral situation here. They may have somewhat looser wiring standards in Panama than here in the US. ---
**Author:** ![Colibri](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/colibri/32/1841_2.png) [@Colibri](https://boards.straightdope.com/u/Colibri)\ **Post date:** [May 22, 2004, 11:34pm UTC](https://boards.straightdope.com/t/why-did-my-extension-cord-melt/246572/33 "2004-05-22T23:34:32Z")
> [@Omphaloskeptic](#): > > Is it possible that the cleaning lady had something else plugged in to the extension cord at the time? It seems pretty coincidental for the cord to have melted during the .5% of the time that the cleaning lady is there, otherwise. The only thing she could have plugged in there would have been the vacuum cleaner, but that’s not functional at the moment. (I didn’t have a replacement for the full dust bag). She says she was cleaning the bathroom, so I don’t think she would even have had the fan on. ---
**Author:** ![Colibri](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/colibri/32/1841_2.png) [@Colibri](https://boards.straightdope.com/u/Colibri)\ **Post date:** [May 22, 2004, 11:37pm UTC](https://boards.straightdope.com/t/why-did-my-extension-cord-melt/246572/34 "2004-05-22T23:37:37Z")
> [@Q.E.D.](#): > > Of course, we could have a reversed hot and neutral situation here. They may have somewhat looser wiring standards in Panama than here in the US. This wouldn’t surprise me in the least. Building construction here is often pretty shoddy in general, and my building is no exception. ---
**Author:** ![Q.E.D](https://avatars.discourse-cdn.com/v4/letter/q/51bf81/32.png) [@Q.E.D](https://boards.straightdope.com/u/Q.E.D)\ **Post date:** [May 22, 2004, 11:44pm UTC](https://boards.straightdope.com/t/why-did-my-extension-cord-melt/246572/35 "2004-05-22T23:44:14Z")
> [@danceswithcats](#): > > Please post your findings, **Q.E.D.** or at least send me an email regarding what you’ve found-digital pictures, too. I’ll share with IAEI and fire service associates. Thanks. Sure, if **Colibri** feels like sending it, I’ll be happy to let you know what I find. ---
**Author:** ![danceswithcats](https://avatars.discourse-cdn.com/v4/letter/d/9e8a1a/32.png) [@danceswithcats](https://boards.straightdope.com/u/danceswithcats)\ **Post date:** [May 22, 2004, 11:47pm UTC](https://boards.straightdope.com/t/why-did-my-extension-cord-melt/246572/36 "2004-05-22T23:47:27Z")
FWIW **Crafter\_Man** , a linear load would equally heat both conductors, hot and neutral. Personally, I look at both conductors with equal suspicion, and may give additional attention to the neutral, given articles about 3rd, 6th, and 9th harmonics which I’ve read, although I doubt their applicability in **Colibri’s** situation. Could a faulty breaker be to blame? Certainly. Federal-Pacific Stab-Lok, Zinnsco, and others are known for delayed-trip problems. That said, there still needs to be a load on the circuit exceeding the cord ampacity for the damage described to take place, and I don’t see it. ---
**Author:** ![Crafter\_Man](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/crafter_man/32/458_2.png) [@Crafter\_Man](https://boards.straightdope.com/u/Crafter_Man)\ **Post date:** [May 23, 2004, 12:03am UTC](https://boards.straightdope.com/t/why-did-my-extension-cord-melt/246572/37 "2004-05-23T00:03:52Z")
> [@Q.E.D.](#): > > Of course, we could have a reversed hot and neutral situation here. They may have somewhat looser wiring standards in Panama than here in the US. Only with the “coding” on the wire (smooth vs. lines, color coding, etc.) No matter how good or screwed up the wiring is, the fact remains that, if only one wire was cooked, it was very likely the _hot_ conductor. > [@danceswithcats](#): > > FWIW Crafter\_Man, a linear load would equally heat both conductors, hot and neutral. Personally, I look at both conductors with equal suspicion, and may give additional attention to the neutral, given articles about 3rd, 6th, and 9th harmonics which I’ve read, although I doubt their applicability in Colibri’s situation. Assuming the over-current situation was _not_ due to a ground fault, _ **any** _ load would equally heat both conductors (assuming the hot & neutral wires had the same resistance per ft). > [@danceswithcats](#): > > Could a faulty breaker be to blame? Certainly. Federal-Pacific Stab-Lok, Zinnsco, and others are known for delayed-trip problems. Even a “good” breaker could be to blame. I seem to recall a thread a while back where it was recommended you manually cycle each breaker once per year. This keeps them from freezing up. ---
**Author:** ![Q.E.D](https://avatars.discourse-cdn.com/v4/letter/q/51bf81/32.png) [@Q.E.D](https://boards.straightdope.com/u/Q.E.D)\ **Post date:** [May 23, 2004, 12:10am UTC](https://boards.straightdope.com/t/why-did-my-extension-cord-melt/246572/38 "2004-05-23T00:10:50Z")
> [@Crafter\_Man](#): > > Only with the “coding” on the wire (smooth vs. lines, color coding, etc.) No matter how good or screwed up the wiring is, the fact remains that, if only one wire was cooked, it was very likely the _hot_ conductor. That was my point, was it not? Of course, if a manufacturing error resulted in a batch of power cord being produced with one wire being a significantly smaller gauge than the other, that could also account for the disparity, as well as the apparent lack of excessive loading causing the problem. ---
**Author:** ![Eleusis](https://avatars.discourse-cdn.com/v4/letter/e/f4b2a3/32.png) [@Eleusis](https://boards.straightdope.com/u/Eleusis)\ **Post date:** [May 23, 2004, 12:38am UTC](https://boards.straightdope.com/t/why-did-my-extension-cord-melt/246572/39 "2004-05-23T00:38:37Z")
> [@Q.E.D.](#): > > If that’s the case, I’d have expected its cord to be damaged as well. But he has two AC adapters on there. If they’re the “wall wart” kind, a short in the adapter could overheat the extension cord without affecting the wire from the adapter to the phone. When you plug the AC adapters directly into the wall, does either one get really hot? ---
**Author:** ![Q.E.D](https://avatars.discourse-cdn.com/v4/letter/q/51bf81/32.png) [@Q.E.D](https://boards.straightdope.com/u/Q.E.D)\ **Post date:** [May 23, 2004, 12:41am UTC](https://boards.straightdope.com/t/why-did-my-extension-cord-melt/246572/40 "2004-05-23T00:41:07Z")
> [@Eleusis](#): > > But he has two AC adapters on there. If they’re the “wall wart” kind, a short in the adapter could overheat the extension cord without affecting the wire from the adapter to the phone. True enough. But then, I’d expect to see some blistering of the case. [Previous page](https://boards.straightdope.com/t/why-did-my-extension-cord-melt/246572.md?page=1) [Next page](https://boards.straightdope.com/t/why-did-my-extension-cord-melt/246572.md?page=3)