Electrical question

[Terry Flowers]

I am pretty new to the Creek, only a few posts so far, and I appreciate the learning experience and friendly atmosphere. Hopefully, some of you electrical/motor experts can help me with an extension cord issue.

For the benefit of my power tools and motors, I just bought a 40 foot 12 gauge cord reel for a decent price from Harbor Freight. I noticed that the 4' length that plugs into the wall is only 14 gauge, not 12.

I am concerned that this smaller wire size, even though it is a short length, might compromise the benefit of having the 12 guage extension cord.

Any thoughts?

Thanks in advance,

Terry

[Rick Christopherson]

Because of its short length, no, it will not have a significant impact on the usability of the reel.

[Terry Flowers]

Thanks Rick.

Terry

[Hoa Dinh]

Terry,

Please note that when using that cord reel, especially for high amperage tool, you need to pull all the cord out of the reel. Otherwise there is a chance of overheating and the cord may melt, not a pretty scene.

-- Hoa

[Charlie Velasquez]

For the benefit of my power tools and motors, I just bought a 40 foot 12 gauge cord reel for a decent price from Harbor Freight.


Check the item number.
Harbor Freight has a recall on their "Heavy Duty Industrial Cord Reel"
Item #42053

See here (http://www.harborfreight.com/cpi/recalls/42053.htm)

If your cord is not the one being recalled, remember that even though the 40' section is 12 gauge, it is probably not rated for 20 amp. The 14 gauge section will limit it to 15 amps; the 12 gauge section is there to help reduce the voltage drop and heat build-up (and as Hoa mentioned, it can still get warm)

[tod evans]

terry, i have a simple cord rule that has served me well for years running handheld powertools, all my 25ft cords are 12ga. all 50ft cords are 10ga, i never hook two 25 ft cords together. .02 tod

[James Suzda]

I am concerned that this smaller wire size, even though it is a short length, might compromise the benefit of having the 12 gauge extension cord.
As you should be concerned about this length of 14 gauge wire. 14 gauge wire is only heavy enough to handle 15 amp and if you have a 20 amp load on your cord you stand a good chance of burning up the lighter wire and it will not blow the fuse or breaker!
BTW, unrolling or uncoiling the wire will not prevent it from heating up. You stand more of a chance of overheating the 4' section of the wire and probably the internal 'sliding connection' used to make the connection between the reel and the connecting cord.
(There was a lot of bandwidth used up on a different forum that I subscribe to on this very subject, and I'm sure it will come up again.)
If you continue to use this cord for lighter duty tools that draw 15 amp or less you will not have any problems.
Jim

[Cliff Rohrabacher]

The longer the run the less amperage you get on the out put end.

[Kyle Kraft]

Roger that!

One should never use extension cords of any kind when coiled up. We experienced a fire at my workplace when they ran temporary power to a building using a generator during a substation shutdown. The cables from the generator to the building were left on a reel and only enough wire was unreeled to reach the building. The reel caught on fire after the generator was on line for a few hours.

[John Downey]

Terry,

As Rick said, it is no problem in this case. In a nutshell the limiting factors in the current carrying capacity of a wire has to do with the resistance of the wire and the temperature that the insulation can stand. Wire has a resistivity specific to its size, material, length, and temperature. All else being equal, the 4' section of 14 awg has a resistance of 0.01 ohms and the 40' section of 12 awg has a resistance of 0.06 ohms. This is why they can get away with using the smaller section for a short distance, though it is the kind of shoddy manufacturing you can expect from Harbor Freight.

As to the risk of fire using a coiled up extension cord, that has to do with the temperature at which the insulation melts. Better quality wires will be ok coiled as long as you're not exceeding the electrical limitations of the wire. Of course, do whatever you're most comfortable with, but in your shoes, I'd try it coiled up under normal use, and check how warm it feels every now and then. If you can touch it with comfort, then there is no real danger, assuming the cord has no bad kinks hidden in the coil. Of course your typical fire marshal will tell you to unplug the cord whenever it is not in use, which I rarely do, so you can take all this with the appropriate dose of salt.

John

[Rick Christopherson]

There is a lot of fear mongering in this thread, and I am not a big fan of this. A coiled cord cannot dissipate heat as efficiently as an open cord, but this does not automatically associate a coiled cord with a meltdown. What’s missing from the equation is the generation of excessive heat. In this case, it is a 12 gauge cord, which is legally capable of sustaining 25 amps in an open-air environment, yet is breaker-limited to 15 or 20 amps, and even further limited by tool demand.
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Is there a risk that a coiled wire will not be able to dissipate the heat it generates? Yes. Is it likely in this case with a 40-foot, 12 gauge cord? No.
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What’s the electrical difference between a coiled cord and an open cord? The coiled cord needs to be derated to account for a reduction in heat dissipation, as does any wire. If this cord carries a UL sticker, you can rest assured that it has already been derated and tested for the ampacity it is intended for, and will dissipate the heat at that level.
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Furthermore, heat generation is both cord-length and time dependant. The thermodynamic properties of the coil are not known, so blindly stating that a coiled cord will melt is nothing more than fear mongering. There is a world of difference between pumping 20 amps through a long cord for hours, versus 15 amps for a few minutes.

[Terry Flowers]

Thanks to all who replied. The different opinions are somewhat confusing, but I think I have a better understanding. It sounds like as long as I don't over burden the cord reel, I should be OK even if it is partially coiled. I can uncoil it after a period of use and check for overheating. If I run a higher amperage motor, I can always uncoil it just to be safe (and hope that the spring holds up and it recoils reliably).

I don't really need 40 feet, so I may just return it (or keep it for lighter duty use) and opt for a shorter heavy duty cord that is not on a reel, thereby minimizing voltage drop.

Again, thanks for all the input,

Terry

[Chris Padilla]

Terry,

FWIW, I had a 100' roll of mostly coiled up (maybe 3/4 coiled, so 25' out) cord in which I connected two hair dryers. I pointed these hair dryers on a massive ice build up on my evaporator coil in the freezer and they were on for a good 15 minutes at full blast.

Now this extension cord was #14 and let me tell you that the sucker got very, very hot. So hot, in fact, that the insulation formed very tightly around the wires contained within: kind of like a very skinny person whose ribs you can see through their skin. Scared the bejesus out of me and I quickly uncoiled the mass to let it cool.

Thankfully, nothing more serious than a change of underwear ensued but I learned a lesson there. Do note, however, that I ran some high-amperage loads and that I did it for quite a long time. In most cases, this is a pretty rare situation (I fixed a bad heater on the freezer...no more ice build-up! :D ) and I've since acquired a nice powerful Milwaukee heat gun. :)

[Rob Russell]

Terry,

FWIW, I had a 100' roll of mostly coiled up (maybe 3/4 coiled, so 25' out) cord in which I connected two hair dryers. I pointed these hair dryers on a massive ice build up on my evaporator coil in the freezer and they were on for a good 15 minutes at full blast.

Now this extension cord was #14 and let me tell you that the sucker got very, very hot. So hot, in fact, that the insulation formed very tightly around the wires contained within: kind of like a very skinny person whose ribs you can see through their skin. Scared the bejesus out of me and I quickly uncoiled the mass to let it cool.

Thankfully, nothing more serious than a change of underwear ensued but I learned a lesson there. Do note, however, that I ran some high-amperage loads and that I did it for quite a long time. In most cases, this is a pretty rare situation (I fixed a bad heater on the freezer...no more ice build-up! :D ) and I've since acquired a nice powerful Milwaukee heat gun. :)

Chris,

Hair dryers are a high draw load. You were almost guaranteed to be pulling more than 15 amps through that extension cord. The length of the cord would have contributed to voltage drop and increased the amperage draw of the dryers. I'm a little surprised 2 dryers on high for that long on a single circuit didn't trip the breaker. You didn't have a 14 gauge cord plugged into a 20 amp circuit, now - did you???:rolleyes:

Rob