Announcement

Collapse
No announcement yet.

What guage do extension cords need to be?

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • Sberry
    replied
    You don't need 6 to run 15A tools at 150 ft. Pole barns and houses are built all the time with a wire like this plugged in to outlets on the side of a building. That chart is really faulty in some sense and remember that the applied load is not the same as the breaker rating. I zing boards off all the time from 100 ft of 16 cord and a circ saw.
    Last edited by Sberry; 10-28-2015, 05:01 PM.

    Leave a comment:


  • freefly23
    replied
    That really helps guys! I think I understand it now. Electrons encounter less resistance as a wire's cross section increases because they have more room to flow through!

    I've been struggling to find an answer to this question online. I hope others with this question will stumble upon this thread. I'm glad I asked on millerwelds this time, and found the answer I was looking for. A big thanks again for everyone's help!
    Last edited by freefly23; 10-27-2015, 03:22 PM.

    Leave a comment:


  • Broccoli1
    replied
    Originally posted by freefly23 View Post
    Thanks so much for replying guys. I did buy a generator.

    So basically you need larger extensions cords at longer ranges to provide the proper voltage, this is the answer I was looking for.

    However, why do larger extensions cords provide more voltage than smaller ones? Is this because the electrons have a larger surface area to travel over? If that is the case, can you also have smaller copper strands inside the same guage wire to provide more surface area and therefore voltage?
    here ya go

    http://www.schoolphysics.co.uk/age14...ce_/index.html

    Leave a comment:


  • OscarJr
    replied
    Originally posted by freefly23 View Post
    Thanks so much for replying guys. I did buy a generator.

    So basically you need larger extensions cords at longer ranges to provide the proper voltage, this is the answer I was looking for.

    However, why do larger extensions cords provide more voltage than smaller ones? Is this because the electrons have a larger surface area to travel over? If that is the case, can you also have smaller copper strands inside the same guage wire to provide more surface area and therefore voltage?

    The whole "electrons travel over the surface of a conductor" (skin effect) only applies to very high transmission frequencies. At 60Hz AC, the entire conductor cross-section is consumed for current transfer. It is of no negative consequence in this case.

    Leave a comment:


  • WillieB
    replied
    Originally posted by freefly23 View Post
    Thanks so much for replying guys. I did buy a generator.

    So basically you need larger extensions cords at longer ranges to provide the proper voltage, this is the answer I was looking for.

    However, why do larger extensions cords provide more voltage than smaller ones? Is this because the electrons have a larger surface area to travel over? If that is the case, can you also have smaller copper strands inside the same guage wire to provide more surface area and therefore voltage?
    Yes, but the difference at 120 Volts, and 15 amps isn't significant. Mostly, stranded wire is used because it is more flexible. Imagine each strand being capable of a current of 1/10 amp without overheating. More conductors sharing the load= more power.

    Leave a comment:


  • freefly23
    replied
    Thanks so much for replying guys. I did buy a generator.

    So basically you need larger extensions cords at longer ranges to provide the proper voltage, this is the answer I was looking for.

    However, why do larger extensions cords provide more voltage than smaller ones? Is this because the electrons have a larger surface area to travel over? If that is the case, can you also have smaller copper strands inside the same guage wire to provide more surface area and therefore voltage?

    Leave a comment:


  • H2o
    replied
    3% loss is under ideal circumstance. I would assume you loose more through possible bad connectors or sometimes, extensions cords. I would assume that some of the super cheap cords could have inferior copper in them as well.

    After contractor left our job, i went through and verified every circuit breaker to make sure all was nice and tight. Found a whole bunch of loose connections... some REAL loose.

    Leave a comment:


  • ryanjones2150
    replied
    Oh ya, that's bad. Let's not do that.

    Leave a comment:


  • WillieB
    replied
    The proof is in the pudding. With your set up, test voltage under full load. If it proves lower than tool rated voltage, you have a bottle neck in your power source. It may not be in your cord. Electrical contractors are forced to compete with the lowest common denominator. If your builder subbed the job to a cheap electrician, or layman, you have a cheap circuit. Wiring may be small, too long, or connections too high resistance. These half hearted connections resisting current will burn down your building.

    Leave a comment:


  • raferguson
    replied
    To clarify a little bit, every table of this type is built on the assumption of a permissible voltage drop, usually 3%. I went ahead and used the web site below, and cranked in 150 feet, 15 amps, 12 ga, and got a voltage drop of 9 volts, around 7.5%. That is quite a bit, but not crazy. Most likely your grinder does not pull 15 amps continuously. What you would notice is a reduction in the power of the grinder, due to the low voltage. You might also be more likely to overheat or burn out the motor, due to the low voltage.

    I would run an experiment, in which I used the grinder with no extension cord, and then used it with the extension cord, and see how noticeable the power loss was. You could also use a voltmeter or Kill A Watt meter to measure the voltage, etc. I would not be real enthused about running power tools below 108 volts, which would be 10% lower than the nominal 120 Volts. For example, for my RV, I will not run the air conditioner below 108 volts.

    I agree that a 6 ga cord is probably impractical, but also unnecessary. Using their web site, an 8 ga cord would have a voltage drop of 2.9 %, which should be very acceptable.

    http://buyextensioncord.com/info_voltage_drop.shtml

    However, what none of these models take into account in the voltage loss in the house wiring. If the outlet is right next to the breaker box, that is probably a minimal voltage drop. But if there is 50 feet of 14 ga wire in the wall, that would be 3.9% voltage drop, not counting the extension cord! That is probably why the table suggests 6 ga cord, rather than the theoretically adequate 8 ga cord. You really need to look at the house wiring, and see how much voltage drop you have there.

    If you have a 15 amp circuit, the smart money might be to run a new outlet, fused for 20 amps, but with 10 or 12 ga wire.

    I don't think that I am disagreeing with anything that folks have already written here.

    Leave a comment:


  • Synchroman
    replied
    If you need to go 150 feet to your work site, you really need a generator. For that distance as shown above, you are going to need 6 gauge to use an extension cord. That would be costly.

    Leave a comment:


  • OscarJr
    replied
    Originally posted by Meltedmetal View Post
    I think it depends what you are doing with the 15 amps at the end of 150 feet of cord. As Willie explained if you can live(or your tools can live) with the voltage drop over that distance then you are good with a smaller cord but if you need a full 15 amps at 100% duty cycle you would have to go with a larger conductor to maintain the voltage at that draw.

    Exactly. The more voltage drop, the more current the tool can attempt to draw from the circuit, which won't always happen due to resistance as well. Will tools work with sub-par wiring sure? But the total power delivery can suffer.

    To answer the OP regarding that chart, you have to look at BOTH the top most row (which dictates the current draw) AND the left most column (which dictates TOTAL length of extension cord). Once you find the current draw on the top-most row, go DOWN that column until you reach the row that is closest to your total extension cord length, Where ever the amp column and cord length row intersect, that is the "optimum" gauge required for the extension cord in order to not suffer heavy voltage losses which will reduce total power delivery at the end of the cord. The power "lost" through the cord ends up as heated copper wiring in the cord itself due to electrical resistance.

    Leave a comment:


  • Meltedmetal
    replied
    I think it depends what you are doing with the 15 amps at the end of 150 feet of cord. As Willie explained if you can live(or your tools can live) with the voltage drop over that distance then you are good with a smaller cord but if you need a full 15 amps at 100% duty cycle you would have to go with a larger conductor to maintain the voltage at that draw.

    Leave a comment:


  • MMW
    replied
    I don't understand what this thread is about? The chart at the top of the page is either not related to the question (if there is one) or taken out of context from somewhere. You would not drag around a 6 gauge, 150' extension cord to run a 15 amp grinder.

    Leave a comment:


  • ryanjones2150
    replied
    Wireless electricity. That would be Tesla's solution.

    Leave a comment:

Working...
X