The physics of the particles bouncing around and moving is what causes the heat isn't it?

That being said, are those particles likely to dam up at the exit end (socket), and bounce around in a tighter space, causing extra heat?

If not at the prong end, but only at the socket end, then maybe physics is playing a role?

If they all do it, then what is the worry?
Just don't run the cord under the carpet.

Heck, I don't know!

Interesting thread.
Thanks

A good way to visualize it is to see the low resistance wire and connections as guides for electrical energy but not the media for energy movement. When resistance is low the energy movement is pointed into the space around the conductors so very little of the energy is absorbed into the conductor particles resulting in little heating. When resistance is high the direction of energy movement tilts more toward the resistive conductor as the media for energy movement as electrical energy is converted to heat as it is absorbed into the resistance.

So if the cords connections are electrically resistive IRT the rest of the wiring, electrical energy will be pulled into those locations causing them to heat at a higher rate than the rest of the circuit.

 

when the contacts heat up, they also corrode easier, that increases the resistance, causing more heat. the plug is easily visable, and gets cleaned more often, the socket end is covered, and isnt easily cleaned for good connection., also, moisture tends to collect in the socket when used outdoors, more corrosion.

 

I usually apply a drop of this on new cords or connectors. I've had the same bottle for at least 15 years so while pricey IMO the stuff works wonders to stop bad connections in the first place and cleans up old contacts quickly.

http://www.amazon.com/dp/B0000YH6F8...vptwo=&hvqmt=b&hvdev=c&ref=pd_sl_4xyery5fst_b

 

when the contacts heat up, they also corrode easier, that increases the resistance, causing more heat. the plug is easily visable, and gets cleaned more often, the socket end is covered, and isnt easily cleaned for good connection., also, moisture tends to collect in the socket when used outdoors, more corrosion.

Good observation... but I can't remember if the live contact corrodes faster than the neutral one, or the other way around.

 

Good observation... but I can't remember if the live contact corrodes faster than the neutral one, or the other way around.

They both carry the same current but the US polarized plugs are wider on the neutral side.

 

They both carry the same current but the US polarized plugs are wider on the neutral side.

I wasn't talking about the current, actually. I was wondering if corrosion is different or tends to accumulate more on the hot contact or the neutral one... just as corrosion is more prominent in the positive pole of a car's battery... but then again, this is AC, not DC, so maybe my question is just plain stupid?...

 

Not really, this is stupid but most of us did it at least once.

 

The physics of the particles bouncing around and moving is what causes the heat isn't it?

That being said, are those particles likely to dam up at the exit end (socket), and bounce around in a tighter space, causing extra heat?

If not at the prong end, but only at the socket end, then maybe physics is playing a role?

If they all do it, then what is the worry?
Just don't run the cord under the carpet.

Heck, I don't know!

Interesting thread.
Thanks

Hello there,

Well the point i am making is that if a good receptacle does not get warm but another one does, then that second one must have more of a problem than the one that does not get warm. Once i fix these things, you cant feel anything, maybe a tiny tiny temperature rise but that's it.
They dont all do it, as i have found one now that stays fairly cool, maybe a tiny bit warm.

This one cord however is the worst, and i am going to post pics of it next.

 

Hello again,

I cut the socket end apart on that more expensive cord. This is what i found so far.

First, the crimps look good. They look tight and made with a good tool that shapes the crimp metal as it should (curls it slightly and makes it tight to the wire).
Second, the wires dont look broken near the crimp itself.
Third, the contacts look clean.
Fourth, the contacts are fairly tight and seem to make a large surface area contact.
Fifth, the wire is the correct gauge and has a decent number of strands that would make it more flexible than regular hook up wire, which is what an extension cord should have.

What i cant see yet (see photos) is what is inside the wires. I'll have to strip the wire to see that. Since the socket contacts look clean and tight, and the crimps look clean and tight, it must be the wire. This would match up with the wire feeling and measuring the hottest near the socket connector.

I guess i'll have to strip the wire next to find out what is going on inside the wire. Since i have the thing apart and did not destroy the connector metal or the crimps or wire, i might just test it again open frame like the last pic shown here. That means i'll be able to test the temperature of everything inside separately.

If anyone has any more ideas about this please post them too, thanks.

 

Not really, this is stupid but most of us did it at least once.

So I'm guessing that the sequence of events was something like:

1. 
   
2. 
3. 
4. 
5. 
6. 
7. 
8. 
9. 

right?

 

Close but we didn't have nice electronic devices to record our stupid 'experiments'.

I would suspect that nothing is wrong with the heat levels on most of the quality cords and what's being seen is mainly just the effect of different heat conduction with different materials from the metal heating in a normal way to the surface of the cord and connectors.

 

Hello,

If you are trying to suggest that this is just par for the course, i dont agree, because for a good cord and replacement end there is almost no heat at all. Keep in mind this is pretty low current here, like 5 to 8 amps tops. It's not like we are stressing the cord to the max.

 

Hello,

If you are trying to suggest that this is just par for the course, i dont agree, because for a good cord and replacement end there is almost no heat at all. Keep in mind this is pretty low current here, like 5 to 8 amps tops. It's not like we are stressing the cord to the max.

8 amps... at 120 Volts is 960 Watts... let's round it up to 1,000 Watts. What's the extension cord's gauge, and the cord's total length?

 

Hello,

If you are trying to suggest that this is just par for the course, i dont agree, because for a good cord and replacement end there is almost no heat at all. Keep in mind this is pretty low current here, like 5 to 8 amps tops. It's not like we are stressing the cord to the max.

I'm saying the heat from a 99% perfect cord @ 1000W gives you 10W of power loss. With good insulation on the wires and a thick overall plastic cover the good thermal conduction path of the metal conductors will transfer heat over time to the ends of the wiring and it will be detected.
http://web.mit.edu/16.unified/www/FALL/thermodynamics/notes/node118.html

 

I'm saying the heat from a 99% perfect cord @ 1000W gives you 10W of power loss. With good insulation on the wires and a thick overall plastic cover the good thermal conduction path of the metal conductors will transfer heat over time to the ends of the wiring and it will be detected.
http://web.mit.edu/16.unified/www/FALL/thermodynamics/notes/node118.html

My point exactly

 

8 amps... at 120 Volts is 960 Watts... let's round it up to 1,000 Watts. What's the extension cord's gauge, and the cord's total length?

Hi,

Yes that's a good way of looking at it, but that doesnt explain why fixing the end works so well.

The gauge is 14 gauge, and the total length is 15 feet.
The wire resistance however measures about 33 percent higher than it should so there might be a problem with the wire inside.

 

I'm saying the heat from a 99% perfect cord @ 1000W gives you 10W of power loss. With good insulation on the wires and a thick overall plastic cover the good thermal conduction path of the metal conductors will transfer heat over time to the ends of the wiring and it will be detected.
http://web.mit.edu/16.unified/www/FALL/thermodynamics/notes/node118.html

Hi,

Yes, good point, even if that's not the whole picture.
I agree completely except for this extension only the one ends gets too warm. It's not dangerously warm, but i dont like that anyway. If i replace the end it will go totally cool in some extensions, although i havent done this one yet. I want to do one more test before i replace the end.
I did measure the resistance at 8 amsp, and it measures 56mOhms which is too high for 14 gauge wire, it should be about 37mOhms for 15 feet. So there could be a problem with the wire.

I am familiar with the partial diff equation for heat conduction with or without heat shielding, but remember heat shielding is still subject to the insulation rating of the shielding which means that the real life example of the extension cord will differ from the textbook examples that have perfect shielding because there is heat loss in the wire over the whole length, even if well insulated. It will be warmer near the ends, but there should be some heat getting through the insulation too.
You are right though that the round cable has more insulation than the standard cheap extension cords with just two zip wires. This cable has three wires inside and a round coating, so it has more insulation to deal with. But then why only the one end gets too warm.

 

there is no problem caused by polarization of the two pins in the plug, there is ac running through, not dc. any proiblems caused by which is hot and which is nutral does not exist, the current reverses 60 times a second.

 

there is no problem caused by polarization of the two pins in the plug, there is ac running through, not dc. any proiblems caused by which is hot and which is nutral does not exist, the current reverses 60 times a second.

That's why I thought... but then again, haven't you noticed that most "polarized" plugs, that is, plugs that have a wide prong for the neutral wire and a narrower one for the live one also use different materials sometimes? Sometimes the neutral prong is plated while the live one is natural copper. I've often wondered why.

 

That's why I thought... but then again, haven't you noticed that most "polarized" plugs, that is, plugs that have a wide prong for the neutral wire and a narrower one for the live one also use different materials sometimes? Sometimes the neutral prong is plated while the live one is natural copper. I've often wondered why.

Perhaps because the 'line' prong, having, as it does, less contact area, requires lower interface resistance to achieve acceptably low (total) connection resistance?

Best regards
HP