In order to participate in the GunBroker Member forums, you must be logged in with your account. Click the sign-in button at the top right of the forums page to get connected.

Extension cord question

WearyTravelerWearyTraveler Member Posts: 2,019 ✭✭✭

I’ve read a couple of conflicting theories.

I have a 100’ 10/3 heavy duty cord and want to keep it on a reel. I’ve read that it’s dangerous to leave it coiled while in use. Some say to run it all out. Other say it’s ok to leave it on the reel...

Any electricians have a reason to not run it all the way out?

Please explain the reasoning...

”People sleep peaceably in their beds at night only because rough men stand ready to do violence on their behalf."


  • charliemeyer007charliemeyer007 Member Posts: 7,346 ✭✭✭
    Not an electrician or electrical engineer.  Heat build up can be an issue.  Short term use is fine (a few minutes, longer with lighter loads) IMHO.  I'm not sure that it doesn't form an inductor with current.
  • Horse Plains DrifterHorse Plains Drifter Forums Admins, Member, Moderator Posts: 37,978 ***** Forums Admin
    If you are carrying high amperage loads on the cord, and it is rolled up on the reel, it can over heat and start to meld down. Whereas if it is uncoiled and stretched out it could dissipate heat.   
  • Mr. PerfectMr. Perfect Member, Moderator Posts: 63,797 ******
    If you are carrying high amperage loads on the cord, and it is rolled up on the reel, it can over heat and start to meld down. Whereas if it is uncoiled and stretched out it could dissipate heat.   

    Yep. I would think the load would need to be somewhat continuous too, like running a shop heater or even a shop vac or something. Intermittent use with power tools that operate only for brief intervals should be completely fine, but if you say run a lot of lumber through a planer all in one go, or a sander for long duration (admittedly I can't think of a high amperage sander) you will want to be cautious about that.
    Some will die in hot pursuit
    And fiery auto crashes
    Some will die in hot pursuit
    While sifting through my ashes
    Some will fall in love with life
    And drink it from a fountain
    That is pouring like an avalanche
    Coming down the mountain
  • OkieOkie Member Posts: 982 ✭✭✭
    From a Registered electrician and electronic tech:
    Whoever says run it out uncoiled is full of BS. When you see that person tell them they have something BROWN On their lips, then tell them it's just BS, it won't rub off. Sounds like someone this person is referring to that is giving you advice.

  • mogley98mogley98 Member Posts: 18,310 ✭✭✭✭
    I know that open air loads on electrical wire are significantly higher than in conduit. When we back feed the hospital with locomotive cable I calculated the load and called the engineer for HCA and said it was too small, he advised me to look at the ratings for open air loads and of course he was right much higher capacity. That said the same would apply to the reel, if you are using the cord for loads well within its range it is probably fine, if you are using it near capacity it would obviously be much better to let it all out and allow it to dissipate heat along its entire run. That said a hundred feet is a long way to carry loads anywhere near capacity if you were talking 12/3 with amps of say 8 I would say rolled was fine
    Why don't we go to school and work on the weekends and take the week off!
  • mrmike08075mrmike08075 Member Posts: 11,826 ✭✭✭

    You might accidentally create your own small high luminosity high energy particle hadron collider and have quarks or muons everywhere or possibly intersecting storage rings leaking relativistic heavy ions...

    Or have your live looped and coiled charged wires accidentally configured to reproduce Tesla's death ray...

    Have you noticed any large black holes that you can't account for???

    Do you have 16 or 17 miles of cord coiled up???

    Is it possible that you generated:

    A somewhat Bizarre pentaquark that turns out to be a new kind of subatomic 'molecule'???

    Is there a Higs Hunter next to your smoke detector and carbon monoxide detector - if the battery has gone bad you might be covered with bosun god particles...


  • select-fireselect-fire Member Posts: 69,482 ✭✭✭✭
    Just 25' on a couple of windup .
  • OkieOkie Member Posts: 982 ✭✭✭
    Yea, sure uncoiling those cords would have made all A-Ok.
    and pee on my leg and tell me it's raining.

  • mogley98mogley98 Member Posts: 18,310 ✭✭✭✭
    A 14 AWG with 60C insulation  buried, in conduit or in a raceway is 15 amps max, open air is 25. makes a big difference
    Why don't we go to school and work on the weekends and take the week off!
  • jimdeerejimdeere Member, Moderator Posts: 23,836 ******
    Google “Allowable ampacities of insulated copper conductors”. 
  • bpostbpost Member Posts: 32,221 ✭✭✭✭
    We are excited to hear of your experiment.  Wrap it up and hook up a 5,000 watt heater, let it run for an hour checking the coil with a laser thermometer.  Let us know what temps you get....
  • spasmcreeksrunspasmcreeksrun Member Posts: 1,762 ✭✭✭
    entirely to much thinking...just plug the 100' into the bathroom outlet and run it out to the shed with a multi stack plug in and hook everything up and test it...if ya cannot see the firetruck coming for the smoke  it may have been to much...any way i have multiple cords leading up to 4-100'  12 guage....or try the new round multi stack unit that winds up the cord i saw on late night tv...made in china , i'll bet.....keep up our good trade relations...and ....SAFETY FIRST
  • Butchdog2Butchdog2 Member Posts: 3,543 ✭✭✭✭
    Not electrician but have been around a lot of extension cords. If it gets hot enough melt the insulation, you are way past overload.
    My 2 cents.
Sign In or Register to comment.