1. Welcome to NikonCafe.com—a friendly Nikon camera & photography discussion forum!

    If you are thinking of buying a camera or need help with your photos, you will find our forum members full of advice! Click here to join for free!

extension cord reels

Discussion in 'General Discussion' started by NZDoug, Aug 14, 2009.

  1. I have a 100 foot /30 meter exension cord and I have been informed that it can form an electronic field because its wrapped around itself.
    I often use it ,say, with 1/2 of it extended but leave the other bit of cord wrapped around in the reel.
    Is this dangerous?:eek: 
  2. Yes that's correct. It can cause biolingualmagneticchorea. Just kidding.
  3. Well if you wrapped it around a piece of metal, you would have a nice magnet:biggrin:
    Never known it to be.
  4. It may generate heat when looped - it becomes an inductor.

  5. Hi folks, THX! for the replies.
    Were 220 volt down under so our electrical stuff has twice the grunt.
    Sean, Ive never felt the reel get hot when running a 3000 watt power Broncolor or Elinchrom pack .
    Maybe its an old wives tale.
    Its a bummer to unravel all 100 feet when you just need a bit of length.
  6. WayneF


    Apr 3, 2006
    Totally insignificant, not at all dangerous in any way with regard to a field. If you only had only one copper wire wound on the spool, and if it were DC current, we could discuss a field. Every field coil you ever saw only used one wire.

    But this power cord is is double conductor (two wires), with current going one way in one wire and going the other way in the other wire (current going out to the cord end, and its return coming back). It is AC, both wires are reversing 50 times a second. But at any instant, currents are opposite directions so that any field of one is opposite polarity of the other, so that any field from one wire neutralizes the field of the other. If you were trying to create a field, you certainly would not approach it with a two wire cable.

    If you changed it to be one wire, and wound the one wire around an iron core to get a little strength, then with DC current you could create a field, and magnetize things with it. With AC current, this one wire and iron core could make a demagnetizer to erase magnetic tapes with it. Or a fairly strong permanent magnet would do that job too. But with a two wire cable, forget it.
  7. pirahnah3


    Feb 22, 2008
    it actually caues the cord to be less usefull, as in the ammount of amps ict can carry safely. if your not using it for anything heavy amp draw you should be ok but if your going to run the max unroll it all.
  8. Old wive's tales. These cords are insulated to prevent any of these things that you've been told may happen. Believe me, it has more insulation than you think. A warm cord only means you're overloading it. But if you begin to vomit living words that stick to metal surfaces, blame Palouse! :tongue:
  9. You got it Lee---oral diarrhea by any name, stinks! :Whistle::Whistle::m76:
  10. Lurker


    Jul 21, 2007
    It's not having a core, the magnetic field effect will be negligible. However, there is also good 'ole Ohm resistance that will generate heat (hint: after using a dryblower for a few minutes unplug it and grab the prongs - you'll be shocked! Not by electricity though, but by how hot they are), and depending on how much power you're drawing, that resistance can generate lots of heat. If the wire is all coiled up that heat can't go anywhere - that's the main reason it is recommended to unwrap those large coils.
  11. Thanks for the replies, gents.
    I think I get it!
    Continuous big grunt, unwind.
    Monitor heat.
  12. Growltiger

    Growltiger Administrator Administrator

    It is true and it is dangerous. I have seen it happen. Meltdown. Normally the reels are marked with the maximum amps unreeled and the maximum amps reeled.

    If you run it at full power on the reel you can feel the reel begin to heat up. After that it will begin to melt the plastic of the cable inside the reel and the result is destruction. You don't want to do this. If the plastic gives off harmful gases as it overheats you could be affected.
  13. Ronald M

    Ronald M

    Nov 10, 2008
    If it gets hot, unwrap it all.

    BTW, that is why they make 5,10,25, 50 foot cords too. Just do not plug them together.
  1. This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
    By continuing to use this site, you are consenting to our use of cookies.