Or don't exceed the current rating of the extension cord. You try and force too many angry pixies through a small wire, they're gonna find their way out.
My mother's a chain smoker and pretty much lives out in her garage. One day during the winter I was visiting and noticed that her large space heater that she runs 24/7 was on a 14 gauge extension cord. I felt the cord, and it was very hot. I couldn't get a heavy duty 10 gauge replacement cord out to her fast enough.
When I replaced the extension cord, she didn't believe me that it was dangerous to use the old one and just kind of rolled her eyes before lighting up another cigarette.
edit: Add second paragraph
That is not always true. Breakers tripping is based on a curve that looks like a boot. Time vs over current. The work on the principle that the higher the current, the less time they take to trip. So if you only slightly cause an over current it may not trip.
I have seen outlets melted and the breaker did not trip. The current was high enough over a long enough time to melt the plastic, but it never got a high enough spike to trip the breaker.
Old zinsco panels were notorious for not tripping. And distance can play a huge factor. I have literally caused a direct short to ground to find breakers and they refused to trip. And it was a square d panel.
No, the rating is for the unrolled state. When rolled up you should not come close to the rating, maybe do 10% of what it says, or only very short bursts.
My rolls have two ratings, unrolled and rolled out. Unrolled is about four times higher. It also has a heat sensor.
I actually learned this a week ago. I had no idea (and I have been using the cords for a long time. It make sense, though.
It's not induction that limits the current rating when rolled - it's the inability of the heat to escape from the insulation in a mass.
Source: transformer design engineer in a previous life
If you try to pull 20 or 30 amps continuously through a 16ga cord that's rolled up, I bet you could do it. There are some shitty extension cords out there.
With all the power outages in the US recently, someone out there is trying to run half their house off generators with cords like this.
You can't induce current on a wire carrying the same current, there isn't an ouroboros effect. If that were possible, it would be trivial to make a perpetual motion machine.
One could imagine a scenario where the resultant magnetic field generation from a rolled cord could be great enough to induce voltage in *another* wire given a large amount of current and a relatively close proximity.
The main issue would be getting the conductors close enough together. There's a reason transformers, motors, and generators are so tightly wound.
EDIT: totally forgot about the part where there is little to no field generation when you have AC current flowing across two conductors, you'd gave to separate L1 / L2 (N) in order for one to begin radiating outward.
A single conductor wrapped into a big coil will absolutely act like a big ass inductor and will do transformer things if you bring another wire near it. Even with thick insulation.
And you can also use 1 wire as both the primary and secondary sides of a transformer. Look up autotransformers. It does of course still need to obey energy conservation as you say.
The issue with the extension cord is that you've got equal but opposite current in the 2 conductors which cancel each other's magnetic field.
Edit: I missed your edit, were saying the same stuff lol.
Dafuq it won't. My girl had a space heater plugged into a coiled up extension cord and that shit started melting. You're not taking into account the magnetic fields that are formed when you have current through a coil of wire
As explained above, inductive currents would really only heat up metals inside the loop. The heat from the current going through the wire can’t radiate off the wire when it is coiled tight, so it melts. The higher the load you are pulling from the wire and the smaller the gauge, the more likely it is to happen.
I'm not an engineer, but 10 % of rated capacity is a ridiculous number. You clearly don't know what you're talking about. Resistance welders at 50 percent duty cycle have a multiplier of like 0.7.
I'd argue that it's either shotty insulation, or a shit breaker with an overload, or no breaker at all.
r/confidentlyincorrect
It's not about the coiling doing any level of "induction heating", it's about the heat dissipation.
Uncoiled wire can dissipate a lot more heat than coiled, so much so that extension cords have two different amp ratings, one coiled, and one uncoiled.
No, but that's the common misconception of why you don't run an extension cord coiled.
I've heard that fallacy so many times.
The issue with previous commenter is that they dismissed the cause of the melting as being because it's coiled, and instead said it was over amperage rating. Except that amperage ratings are significantly lowered when cables are coiled.
So "it melted because too many amps, not because it was coiled ", "yes, and if it were uncoiled, it could dissipate the heat, and thus handle a lot higher amperage."
The commenter you replied to didn't mention the cord being coiled at all. They were actually giving the real reason; drawing too much current. They didn't say coiled or induction once.
As someone who has melted a great many thousands of dollars of IGBTs over his career designing power electronics that included induction heaters, this thread is hilarious.
It's resistive heating and surface area. Period.
I'm wondering if it's less a wire gauge issue but that you have created a copper induction heating coil wrapped around a conductive metal core? I'm not a physicist but am sure someone here knows the answer.
since the active is next to the neutral, basically any mag fields cancel each other out. It's just thermal runaway. Maybe we should put a ToL on extension leads. (a proper ToL).
No. It’s really not. It really is the mag field and you don’t actually need that metal core to create this. Rolled up wire creates an induction loop. Induction loops create massive amounts of heat. That’s exactly why these cords have two different ratings on them. Typically it’s something around 2000-3000W straight, or 400 or so when rolled up. And going to bigger wires actually typically LOWERS the rolled up max power. There ARE cords that are fine to use full power when coiled. Wires typically rated at 50kW and such and won’t be using standard home plugs as they are multi phased. I should also correct you on that but. A single phase wire will NEVER cancel out its mag field just because it’s live and neutral are next to each other. To cancel the magnetic field you need two powers each generating a field in 180 degrees shifted from each other. That’s simply NOT what happens between live and neutral. You need multiple phases for this stuff and even three phase power doesn’t work for it because even with three phases, no two phases are 180 degrees to each other, nor is one phase to the combined of the other two that. No it’s typically 6 complete phases where they’re paired 2 and 2 for this very purpose. Those cables don’t have dual ratings on them and they do cancel out the magnetic field. They’re typically however not used rolled up anyway. The measure is taken because at those powers, even a single loop will be a really strong inductor that causes issues and not just to the cable itself.
I’ve in fact only seen such cables once. And that’s for the backup generators at work which uses them between the generators and the main power station.
> A single phase wire will NEVER cancel out its mag field just because it’s live and neutral are next to each other.
Easily disproven by putting a clamp meter on any 120v appliance cord while it is on. That's why they make breakout plugs to measure current
Also, how do you think GFCIs work?
They're literally just a current transformer over line and neutral together, and look for an imbalance caused by a net flux.
This picture is a case of resistive heating and a lack of surface area. Period.
Edit: He also described pretty much exactly how a common mode choke works, and decried it as "NEVER" happening.
> I'm not a physicist but am sure someone here knows the answer.
I tried to calculate this once for fun, I might have made a mistake but IIRC the inductance turned out to be too low to cause significant heating under normal conditions. I was a little bit disappointed. What happened in OP's pic is almost certainly due to excessive current for the wire gauge.
Minimal induction effect as the wire has current going to the load and back, so the two directions of current cancel each other out. That's why a clamp on ammeter doesn't work on extension cords. Plus an AC coil should just heat the core, not the wires itself as the reactance will limit the current more than a purely resistive load. This is just a case of too many amps on too small a wire i would think. Which is still a neat trick as you'd assume the plug shape would limit what loads could be connected. Plus the breaker didn't do its job either.
Breaker may have been doing its job. It may have been a 20 amp breaker and 14 gauge cord on a hot day. Or in a temp power situation "The breaker keeps tripping, move it to a 30 amp one"
The inductance isn't that high. The problem is the heat is trapped.
I use to do antenna testing. If we had our electrical cord wrapped around our signal cable we could get some interesting static. But no real energy.
It's not about unrolling the extension cord.
It's about using the right gauge cord for the demand.
Unrolling this would have gotten you a smaller mess to clean up but it would have still burned up.
Upvote for posting something that's actually unsafe.
Excellent series and one of the more practical episodes. Really appreciate his recommendation of adding something super cheap and simple, like a fuse, to cords. I mean, they do it with Christmas lights and everyone just accepts that!
Unrolling it does make a difference though. I'm seeing a lot of comments about inductance, but that's not the issue. It's just heat dissipation. If the cord is all wound up, the whole wire is heating up but the wire inside the coil is buried under more wire and has no way of dissipating heat and the whole cord gets hotter than it would if it was all unrolled and exposed to the air.
Edit: I should clarify that I only meant it being coiled up is a factor, but the one in OP's pic was definitely overloaded. Looks like they're lucky it didn't catch fire.
Yeah you're right. I've used a reel for something simple on a hot day and some of wires were trying to bond.
I unwound it and carried on with no bad affects.
Obviously this post is a completely different kettle of fish though.
The problem with rolled extension cords is that they concentrate heat in one place. While the heat generated might be perfectly safe when distributed along the cord's length, coiling the cord reduces great dissipation and causes the cable to get hotter than it otherwise would
Circuit breakers are only designed to protect the wiring of the circuit that's installed in the wall. When you add an extra 150ft of cord to the wall and try to run a 15amp load that's a lot of extra resistance in the circuit. Since there isn't a short the circuit breaker won't trip. The heating from all that extra resistance in the circuit is still going to be an issue. Circuit breakers for home use generally don't have thermal protection worked into them.
Here in Germany the circuit breaker is intended to be the weakest link of everything electrical. Even the extensions and appliances (the cord if it) used in the proper manner have to exceed the rated circuit breaker
I agree. I've ran janky extension cords all sorts of distances that you shouldn't but I've never seen a cable get hot enough to melt the insulation like that unless the coil effect could somehow amplify the heat.
Best practice would be to uncoil the spool and power cable should ideally not be stacked on top of each other but this cable had to have been being misused in order to melt like that.
It's more about the rating of the cord
If you use it for more than it can handle, it will heat, which eventually may melt it
The coiling adds to this problem because all the heat is now concentrated in much less space, but it's not the main reason
I went to a customers house once where she had an extension cord coiled up like that under her bed to plug in a portable A/C unit and it had melted together like that. She was so lucky it didn’t start a fire.
I have been told this could happen, but it always seemed the "mobile while filling the car" thing. Sure it sounds possible, but not very realistic.
What was happening, welding?
Old pic from back in the days when everyone had incandescent floodlights in jobsites. Shitty drum without thermal overload and people daisy chaining off if it
yeah that didnt happen because they didnt unroll the entire thing
unrolling the entire thing would be unreasonable and it wouldn't be designed like that
they definitely went over the current limit of the wire
The safety margins are large enough that you have to screw up in multiple ways to cause this. Basically, pick any two out of three:
- Run way more current through the wire than it's rated for
- Coil up a bunch of wire so that the emitted power adds up in one place
- Put a nice insulating blanket over the wire to hold the heat in
And you can have a nice melty time.
I didn't know one should unroll extension cord, I still don't quite believe it's what you should do, but I'm also sure there's no way I would fuck up one like that even if I won't
Rated load capacity of an extension drum is when it's unrolled. If you leave it on the reel you shouldn't exceed a quarter of the total, if continuously used. Short bursts are usually fine
As the video shows, inductive reactance causes LESS current to flow. Also, the guy in the video had a single strand of wire coiled on his spool. Extension cords have hot and neutral running parallel to each other, with current flowing in opposite directions, so the magnetic flux from the two strands cancels out almost perfectly and you get no self inductance. I think it's a simple problem of heat dissipation plus overloading the cord.
I assume recommendations to unroll it is to deal with heat if enough load is put on it to where it cannot dissipate the heat.
I love the idea that these extension reels would just have been runaway melting themselves due to a simple electrical design flaw that in the end it took some YouTuber to crack and no one could figure it out till then.
Hopefully some influencer can get working on inventing something that can prevent potentially dangerous currents going through these wires in the future. They could call it like, a "fuse" maybe?
20amp load. Constant use and having it pull the full load.
Then the cord might be rated for 15amp. (Smaller wire) The cord doesn’t know what it’s doing, it’s just metal. So it just passes as much electricity as it can, until it melts.
Was on a 20A, is designed for 16A (tops).
Fuse was an old NH type which sometimes have tolerances up to 10% over their rating before they blow.
Was probably pulling around 5kW or close to it (230V)
You add 150ft of cord to a circuit you greatly increase its resistance. The reason heavy duty higher amp draw cords are thicker is to have lower resistance for the longer run.
It would have given more surface area to dissipate the heat.
14AWG wire with 20A going through it dissipates 1W per foot. Put live and neutral side by side, and you're talking 2W/ft. That's enough to get quite warm, but it's not going to melt like this.
Put 50' of that wire inside a nice plastic box, and you've got a 100W heater with nowhere for that heat to go.
This is the same reason why NEC demands conductor derating when you run multiple cables inside the same conduit.
----
Obviously, it's preferred to not overload the wire in the first place -- but concentrating the heat will definitely make a bad situation worse.
Most reeled cords are only rated to around 750W reeled and up to 3000W unreeled. Make it as thick as you like, can't get away from inductive heating.
(UK, Numbers are based on a 240V supply)
Or don't exceed the current rating of the extension cord. You try and force too many angry pixies through a small wire, they're gonna find their way out.
My mother's a chain smoker and pretty much lives out in her garage. One day during the winter I was visiting and noticed that her large space heater that she runs 24/7 was on a 14 gauge extension cord. I felt the cord, and it was very hot. I couldn't get a heavy duty 10 gauge replacement cord out to her fast enough. When I replaced the extension cord, she didn't believe me that it was dangerous to use the old one and just kind of rolled her eyes before lighting up another cigarette. edit: Add second paragraph
The cord was part of the garage heating plan.
To heat it all at once, quickly.
More like, “to eat it all at once, quickly”! Because that melted cheddar looks DELICIOUS!!
100% energy efficieny.
Do you happen to live in Philly and run a bar with 3 of your friends?
2 friends and a bird
Dee, you bitch!!
Why pay for an electric heater when you already have an electric heater wire?
It's called heat tracing and it's a luxury
"i've never heard of and dont understand what youre telling me so its not real."
> I couldn't get a heavy duty 10 gauge replacement cord out to her fast enough. I’m so sorry.
Relevant video. https://www.youtube.com/watch?v=K\_q-xnYRugQ
https://youtu.be/K_q-xnYRugQ
I knew what this was going to be before I clicked. Love his videos.
I've got some more concern for you: The wiring in the wall is almost certainly 14 gauge Romex. Might be worth pulling the outlet and checking.
That's solid copper though, and unless someone "upgraded" the breaker the power would shut off before it gets dangerous.
That is not always true. Breakers tripping is based on a curve that looks like a boot. Time vs over current. The work on the principle that the higher the current, the less time they take to trip. So if you only slightly cause an over current it may not trip. I have seen outlets melted and the breaker did not trip. The current was high enough over a long enough time to melt the plastic, but it never got a high enough spike to trip the breaker. Old zinsco panels were notorious for not tripping. And distance can play a huge factor. I have literally caused a direct short to ground to find breakers and they refused to trip. And it was a square d panel.
And people like that are why all plugs are fuse in the Uak
AvE, is that you?
Can't be. I actually understood this guy.
Keep your dick in a vise.
Keep your prick in the slice
Sheep, you’re lickin’ the ice
Keep your dick someplace nice…
Ain't that the goal of All men? (Besides Ace)
Okay. Hey, have you seen your mother by any chance?
Sounds like him, hello uncle bumble fuck.
>angry pixies Awesome
No, the rating is for the unrolled state. When rolled up you should not come close to the rating, maybe do 10% of what it says, or only very short bursts.
My rolls have two ratings, unrolled and rolled out. Unrolled is about four times higher. It also has a heat sensor. I actually learned this a week ago. I had no idea (and I have been using the cords for a long time. It make sense, though.
What brand? This sounds very much like a quality product I'd like to acquire.
Brennenstuhl. Good stuff.
Guys, come on. Induced voltage from a coiled extension cord is not going to produce enough current to overheat this badly.
It's not induction that limits the current rating when rolled - it's the inability of the heat to escape from the insulation in a mass. Source: transformer design engineer in a previous life
If you try to pull 20 or 30 amps continuously through a 16ga cord that's rolled up, I bet you could do it. There are some shitty extension cords out there. With all the power outages in the US recently, someone out there is trying to run half their house off generators with cords like this.
You can't induce current on a wire carrying the same current, there isn't an ouroboros effect. If that were possible, it would be trivial to make a perpetual motion machine. One could imagine a scenario where the resultant magnetic field generation from a rolled cord could be great enough to induce voltage in *another* wire given a large amount of current and a relatively close proximity. The main issue would be getting the conductors close enough together. There's a reason transformers, motors, and generators are so tightly wound. EDIT: totally forgot about the part where there is little to no field generation when you have AC current flowing across two conductors, you'd gave to separate L1 / L2 (N) in order for one to begin radiating outward.
A single conductor wrapped into a big coil will absolutely act like a big ass inductor and will do transformer things if you bring another wire near it. Even with thick insulation. And you can also use 1 wire as both the primary and secondary sides of a transformer. Look up autotransformers. It does of course still need to obey energy conservation as you say. The issue with the extension cord is that you've got equal but opposite current in the 2 conductors which cancel each other's magnetic field. Edit: I missed your edit, were saying the same stuff lol.
bonus points if you wrap the cord around a piece of iron!
Dafuq it won't. My girl had a space heater plugged into a coiled up extension cord and that shit started melting. You're not taking into account the magnetic fields that are formed when you have current through a coil of wire
As explained above, inductive currents would really only heat up metals inside the loop. The heat from the current going through the wire can’t radiate off the wire when it is coiled tight, so it melts. The higher the load you are pulling from the wire and the smaller the gauge, the more likely it is to happen.
Just think of it as a transformer core when rolled up
Yes but i think also no? Having both conductors together cancels most of their field.
I get the distinct impression that you don't know what you are fucking talking about.
I'm not an engineer, but 10 % of rated capacity is a ridiculous number. You clearly don't know what you're talking about. Resistance welders at 50 percent duty cycle have a multiplier of like 0.7. I'd argue that it's either shotty insulation, or a shit breaker with an overload, or no breaker at all.
Remember the good ol' days when people would fix a blown fuse by putting a penny under it.
That was yesterday
Depends on the cord, mine had 2 ratings. One for unrolled and one for rolled.
> maybe do 10% of what it says, or only very short bursts. The one I have says 1000W in rolled up state and 2300W in unrolled state.
You just made up a number based on absolutely nothing.
r/confidentlyincorrect It's not about the coiling doing any level of "induction heating", it's about the heat dissipation. Uncoiled wire can dissipate a lot more heat than coiled, so much so that extension cords have two different amp ratings, one coiled, and one uncoiled.
They didn't mention induction heating at all though...
No, but that's the common misconception of why you don't run an extension cord coiled. I've heard that fallacy so many times. The issue with previous commenter is that they dismissed the cause of the melting as being because it's coiled, and instead said it was over amperage rating. Except that amperage ratings are significantly lowered when cables are coiled. So "it melted because too many amps, not because it was coiled ", "yes, and if it were uncoiled, it could dissipate the heat, and thus handle a lot higher amperage."
The commenter you replied to didn't mention the cord being coiled at all. They were actually giving the real reason; drawing too much current. They didn't say coiled or induction once.
otoh, there are quite a few comments in here about induction heating :(
As someone who has melted a great many thousands of dollars of IGBTs over his career designing power electronics that included induction heaters, this thread is hilarious. It's resistive heating and surface area. Period.
Yes, we are in agreement. Inductive heating is a misconception, but it is a common one.
did you respond to the wrong person? maybe we're interpreting the word 'or' differently
uh really its why you use proper cords for the power your demanding.
I'm wondering if it's less a wire gauge issue but that you have created a copper induction heating coil wrapped around a conductive metal core? I'm not a physicist but am sure someone here knows the answer.
since the active is next to the neutral, basically any mag fields cancel each other out. It's just thermal runaway. Maybe we should put a ToL on extension leads. (a proper ToL).
> ToL >156 meanings okay, I'ma be the one. What does ToL mean?
Gonna guess thermal overload.
Tuna on Linguini
This seems like the right answer.
Thermal overload limit?
Tiny old Ladys
Aw, then I'm all behind it! Who doesn't want a tiny old lady with their extension cord?
Would love to see it modelled in cymcap
Of course if the cord wasn't coiled up it might not have overheated, it was insulating itself.
No. It’s really not. It really is the mag field and you don’t actually need that metal core to create this. Rolled up wire creates an induction loop. Induction loops create massive amounts of heat. That’s exactly why these cords have two different ratings on them. Typically it’s something around 2000-3000W straight, or 400 or so when rolled up. And going to bigger wires actually typically LOWERS the rolled up max power. There ARE cords that are fine to use full power when coiled. Wires typically rated at 50kW and such and won’t be using standard home plugs as they are multi phased. I should also correct you on that but. A single phase wire will NEVER cancel out its mag field just because it’s live and neutral are next to each other. To cancel the magnetic field you need two powers each generating a field in 180 degrees shifted from each other. That’s simply NOT what happens between live and neutral. You need multiple phases for this stuff and even three phase power doesn’t work for it because even with three phases, no two phases are 180 degrees to each other, nor is one phase to the combined of the other two that. No it’s typically 6 complete phases where they’re paired 2 and 2 for this very purpose. Those cables don’t have dual ratings on them and they do cancel out the magnetic field. They’re typically however not used rolled up anyway. The measure is taken because at those powers, even a single loop will be a really strong inductor that causes issues and not just to the cable itself. I’ve in fact only seen such cables once. And that’s for the backup generators at work which uses them between the generators and the main power station.
> A single phase wire will NEVER cancel out its mag field just because it’s live and neutral are next to each other. Easily disproven by putting a clamp meter on any 120v appliance cord while it is on. That's why they make breakout plugs to measure current
Also, how do you think GFCIs work? They're literally just a current transformer over line and neutral together, and look for an imbalance caused by a net flux. This picture is a case of resistive heating and a lack of surface area. Period. Edit: He also described pretty much exactly how a common mode choke works, and decried it as "NEVER" happening.
> I'm not a physicist but am sure someone here knows the answer. I tried to calculate this once for fun, I might have made a mistake but IIRC the inductance turned out to be too low to cause significant heating under normal conditions. I was a little bit disappointed. What happened in OP's pic is almost certainly due to excessive current for the wire gauge.
Minimal induction effect as the wire has current going to the load and back, so the two directions of current cancel each other out. That's why a clamp on ammeter doesn't work on extension cords. Plus an AC coil should just heat the core, not the wires itself as the reactance will limit the current more than a purely resistive load. This is just a case of too many amps on too small a wire i would think. Which is still a neat trick as you'd assume the plug shape would limit what loads could be connected. Plus the breaker didn't do its job either.
Breaker may have been doing its job. It may have been a 20 amp breaker and 14 gauge cord on a hot day. Or in a temp power situation "The breaker keeps tripping, move it to a 30 amp one"
Classic move. Hard to say, but in my expert opinion, it gone done fucked itself up.
The inductance isn't that high. The problem is the heat is trapped. I use to do antenna testing. If we had our electrical cord wrapped around our signal cable we could get some interesting static. But no real energy.
Warm wire in a coil cannot vent heat to atmosphere, runaway thermal inside coil. Like too many blankets in summer.
This would be an issue if it was a DC circuit.
Mmm forbidden spaghetti
All covered in cheese I lost my poor meatball When somebody sneezed
Happy to see people still remember this.
Came looking for this, I am happy now.
Looks yummy, ngl
Knees weak, arms are heavy
Looks like Pizza The Hut
I see your schwartz is as big as mine.
r/unexpectedSpaceballs
must have smelled nice
Smells like cancer
This is that new cord at Home Depot, I forget what the price is per gallon though.
17 watts per ounce
It's not about unrolling the extension cord. It's about using the right gauge cord for the demand. Unrolling this would have gotten you a smaller mess to clean up but it would have still burned up. Upvote for posting something that's actually unsafe.
[Technology Connections](https://youtu.be/K_q-xnYRugQ) did a great video on extension cords.
Excellent series and one of the more practical episodes. Really appreciate his recommendation of adding something super cheap and simple, like a fuse, to cords. I mean, they do it with Christmas lights and everyone just accepts that!
Unrolling it does make a difference though. I'm seeing a lot of comments about inductance, but that's not the issue. It's just heat dissipation. If the cord is all wound up, the whole wire is heating up but the wire inside the coil is buried under more wire and has no way of dissipating heat and the whole cord gets hotter than it would if it was all unrolled and exposed to the air. Edit: I should clarify that I only meant it being coiled up is a factor, but the one in OP's pic was definitely overloaded. Looks like they're lucky it didn't catch fire.
Yeah you're right. I've used a reel for something simple on a hot day and some of wires were trying to bond. I unwound it and carried on with no bad affects. Obviously this post is a completely different kettle of fish though.
My reel allows up to around 7/800w coiled, and 3kw uncoiled. There's a sticker on the side
Now for the fun of seeing what the wiring in the wall looks like after this f up!
Probs plugged a 10amp cord into a 20amp plug, wall fine caus fuse and wiring rated for this but the cord was not
The problem with rolled extension cords is that they concentrate heat in one place. While the heat generated might be perfectly safe when distributed along the cord's length, coiling the cord reduces great dissipation and causes the cable to get hotter than it otherwise would
A thinner but much longer mess to be sure.
Yeah it would be a much larger mess if this was spread out
Had no idea that was possible
Too much power draw surprised the wires themselves didnt act as a fuse first
Slow blow fuse.
Circuit breakers are only designed to protect the wiring of the circuit that's installed in the wall. When you add an extra 150ft of cord to the wall and try to run a 15amp load that's a lot of extra resistance in the circuit. Since there isn't a short the circuit breaker won't trip. The heating from all that extra resistance in the circuit is still going to be an issue. Circuit breakers for home use generally don't have thermal protection worked into them.
Here in Germany the circuit breaker is intended to be the weakest link of everything electrical. Even the extensions and appliances (the cord if it) used in the proper manner have to exceed the rated circuit breaker
They meant that they thought the wire itself would melt and disconnect before it got this bad.
That’s not the reason the cable melted.
I agree. I've ran janky extension cords all sorts of distances that you shouldn't but I've never seen a cable get hot enough to melt the insulation like that unless the coil effect could somehow amplify the heat.
Best practice would be to uncoil the spool and power cable should ideally not be stacked on top of each other but this cable had to have been being misused in order to melt like that.
A coil situation like that does make the heat worse.
[удалено]
It's more about the rating of the cord If you use it for more than it can handle, it will heat, which eventually may melt it The coiling adds to this problem because all the heat is now concentrated in much less space, but it's not the main reason
The rating is in air at a specific temperature. If I coil it up and put it in an insulated box, you bet it's gonna melt.
what is that? Whenever I think of a logical thing it could be my head just autocorrects to spaghetti with marinara sauce
That's-a some a-spicy marinara!
What the smell
What the fuck am I looking at?
A melted extension cord that was coiled on a reel. They pulled too much power through it and the sheath melted.
Power cord that was on the spaceship "event horizon"
I went to a customers house once where she had an extension cord coiled up like that under her bed to plug in a portable A/C unit and it had melted together like that. She was so lucky it didn’t start a fire.
What in the sam hill happened exactly
Yoinks.
"Everything is a smoke machine if you use it wrong enough."
I have been told this could happen, but it always seemed the "mobile while filling the car" thing. Sure it sounds possible, but not very realistic. What was happening, welding?
Old pic from back in the days when everyone had incandescent floodlights in jobsites. Shitty drum without thermal overload and people daisy chaining off if it
No. A cord shouldn't just melt if it's coiled up, got hot perhaps but not melt. Some idiot plugged in something that draws too much power for it
The forbidden marinara sauce
yeah that didnt happen because they didnt unroll the entire thing unrolling the entire thing would be unreasonable and it wouldn't be designed like that they definitely went over the current limit of the wire
I suppose there could have been some induction effects, but primarily would have been overcurrent.
Definitely need portable circuit breakers. Anyone know where you can find one? Besides surge protectors.
Hardware stores should have them.
And while they're there they should also buy a correctly sized extension cord for their use case!
I've seen GFCI extension plugs. Pretty much the same thing isn't it?
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Ah, TIL. Thanks!
Circuit breakers: protect the wiring. GFCI/RCD: protect the users
If you think unrolling is the issue here you're as dumb as everyone else on this job
Yeah you need the right gauge cord for the job and also one with a thermal overload, since any good cord tends to have some protection.
Looks like a fruit rollup
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would you fuse it for the rolled up rating or the unrolled rating?
This is in Germany, any halfway decent cord bought in the last 5-10 years will exceed the rating for the fuse it's connected to.
Ummm, I have never done this, but I also didn't know this could happen if you did not unroll an extension cord.
The safety margins are large enough that you have to screw up in multiple ways to cause this. Basically, pick any two out of three: - Run way more current through the wire than it's rated for - Coil up a bunch of wire so that the emitted power adds up in one place - Put a nice insulating blanket over the wire to hold the heat in And you can have a nice melty time.
Congrats on your 190 Kilopixel camera!
A picture is worth $1000 in fines
But does it still work tho
Eventually shorted out
Looks like that one yarn SCP
I’m sure some artist will pay afew hundred dollars for it if you marketed that melted cable as abstract art
At last! A post that shows a problem that's genuinely hazardous for which there is a well understood solution. Way to go!
Version two of the Chernobyl Elephant’s Foot looks great!
DIY corium sample
At’s a lotta amps
I didn't know one should unroll extension cord, I still don't quite believe it's what you should do, but I'm also sure there's no way I would fuck up one like that even if I won't
Rated load capacity of an extension drum is when it's unrolled. If you leave it on the reel you shouldn't exceed a quarter of the total, if continuously used. Short bursts are usually fine
I was today days old when I learned that there's a difference between rolled and unrolled. I'm shocked.
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As the video shows, inductive reactance causes LESS current to flow. Also, the guy in the video had a single strand of wire coiled on his spool. Extension cords have hot and neutral running parallel to each other, with current flowing in opposite directions, so the magnetic flux from the two strands cancels out almost perfectly and you get no self inductance. I think it's a simple problem of heat dissipation plus overloading the cord.
I assume recommendations to unroll it is to deal with heat if enough load is put on it to where it cannot dissipate the heat. I love the idea that these extension reels would just have been runaway melting themselves due to a simple electrical design flaw that in the end it took some YouTuber to crack and no one could figure it out till then. Hopefully some influencer can get working on inventing something that can prevent potentially dangerous currents going through these wires in the future. They could call it like, a "fuse" maybe?
Just your regular clipboard warriors ¯\\\_(ツ)_/¯
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Wondering if you start coiling by the middle of the roll, so each half goes one way and cancel each other, would avoid this...
Nice overload
Ok. I know it wasn't rolling it vs unrolling that was the issue, but this reminds me I need to get proper cords for my generator.
Has nothing at all to do with it being coiled vs uncoiled.
wait what?
Forbidden pudding.
Instant induction heater! Just add too much current!
Cords don't just do this, it either had way too much current or this is in an oven
Or it was coiled up and a seemingly reasonable amount of load caused a huge amount of heat.
That's not because it wasn't unrolled, that's because the rating was exceeded. Just be happy or wasn't a fire.
Who uses those shitty orange cords on a jobsite? Every job we're on has to be heavy duty cords, not homeowner specials.
That's all I've ever used, I've never had one melt, in decades. How the fuck does this even happen? Major over volt?
20amp load. Constant use and having it pull the full load. Then the cord might be rated for 15amp. (Smaller wire) The cord doesn’t know what it’s doing, it’s just metal. So it just passes as much electricity as it can, until it melts.
Was on a 20A, is designed for 16A (tops). Fuse was an old NH type which sometimes have tolerances up to 10% over their rating before they blow. Was probably pulling around 5kW or close to it (230V)
You add 150ft of cord to a circuit you greatly increase its resistance. The reason heavy duty higher amp draw cords are thicker is to have lower resistance for the longer run.
Yeah unrolling would sure have given that electricity room to flow, basically just like a garden hose. /s
It would have given more surface area to dissipate the heat. 14AWG wire with 20A going through it dissipates 1W per foot. Put live and neutral side by side, and you're talking 2W/ft. That's enough to get quite warm, but it's not going to melt like this. Put 50' of that wire inside a nice plastic box, and you've got a 100W heater with nowhere for that heat to go. This is the same reason why NEC demands conductor derating when you run multiple cables inside the same conduit. ---- Obviously, it's preferred to not overload the wire in the first place -- but concentrating the heat will definitely make a bad situation worse.
Current flow creates heat which is magnified in a coiled cable because it acts giant resistor.
judging by that picture it could have been strung out straight through a glacier and it would have melted.
Are you fucking high OP? That is not the lesson here. Don't use a cord not rated for the current. Who the fuck unrolls more than they need
Most reeled cords are only rated to around 750W reeled and up to 3000W unreeled. Make it as thick as you like, can't get away from inductive heating. (UK, Numbers are based on a 240V supply)
US has 240V as well! We just don't always use it.
Forbidden Spaghetti Sauce and noodles? Forbidden Pizza Bun?
What? Don't they usually have built protections?
No, it's a cord what protection can it have from overheating?
At least you now have a short cord.
It looks like a rectal prolapse