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  • Extension Cords

    Hey guys, is a 100' (12 Gauge) extension cord sufficient for a 15amp circular saw? I've seen a couple of charts and a few show that it would be okay, but the chart in my circular saw owners manual states that if I need 50' of cord, it would have to be a 12 gauge cord. Also, the owners manual does not give an option for a 100' extension cord when using a 12.1-16.0 amp tool, but it does show that a tool with an amp rating of 7.1-12.0 must use a 10 gauge cord if the cord is going to be a 100' long. Why would the charts have different information? Thanks.

  • #2
    Re: Extension Cords

    This depends on the Voltage drop they consider to be OK. At 100 feet for a circular saw, I would really recommend using a 10 gauge extension cord. In addition be sure it's on a circuit wired with #12 or #10 wire and has a 20 Amp breaker. The receptacle should not be too far from your load center (breaker panel) of you'll need to figure in the Voltage drop at the receptacle in addition to that of the extension cord. If you have or know someone that has a good AC Voltmeter rig up a good way to measure Voltage at the tool both with it running under load and also with it off. If the drop is over 5% you need heavier wiring. A well made saw can run on as low as 105 Volts as long as you don't work it hard and bog down the motor. If you do need to work it hard be sure there's no less than 112 Volts right where the power cord plugs in and with it under heavy loading. (That's working the saw pretty hard during the Voltage measuring.)

    If all the above seems confusing, just go with the 10 gauge extension cord and plug it into a receptacle as close as you can to the breaker panel.

    Are you on a job site, or trying to run tools in your garage?

    Please note that most (but not all) extension cords and residential receptacles & plugs are rated at no more than 15 Amps. Some super duty 10 gauge extension cords have 20 Amp plugs and connectors on them. This is what you want. Then be sure the receptacle is a 20 Amp rated one too. You can plug in 15 Amp plugs. Please note the T slot.

    To make this really simple the answer to question 1 is NO. A 12-3 extension cord of 100 feet is not heavy enough for a 15 Amp load. While you can maybe pull it off if you just make a quick cut, then let the saw rest a minute or two and make one quick cut again, you will have a notable loss of power. If you run the saw for long, it will overheat the motor.
    Last edited by Old Grunter; 08-07-2008, 07:37 PM.

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    • #3
      Re: Extension Cords

      50 foot 12 gauge is okay, but you need 10 gauge for 100 feet, at least according to the specs on my 15 amp chop saw.

      For circular saw, you should be using cordless if you're that far from a power source.
      I'm on "The List" and I love it!!

      Comment


      • #4
        Re: Extension Cords

        Thanks, I really appreciate the help guys. I have four 100' (12 Gauge) cords....I guess I'll take one and make two 50' cords.

        Comment


        • #5
          Re: Extension Cords

          Originally posted by 3mw View Post
          Thanks, I really appreciate the help guys. I have four 100' (12 Gauge) cords....I guess I'll take one and make two 50' cords.
          It doesn't work like that. Two 50' cords is the same as a 100' cord for figuring the voltage drop.

          Comment


          • #6
            Re: Extension Cords

            Originally posted by cpw View Post
            It doesn't work like that. Two 50' cords is the same as a 100' cord for figuring the voltage drop.
            Really, when in series or parallel?



            I'm gonna hazard a guess that he meant he was going to make two useful 50' foot cords that would be used alone out of the 100' undersized cord.
            "When we build let us think we build forever. Let it not be for present delight nor for present use alone. Let it be such work that our descendants will thank us for, and let us think, as we lay stone upon stone, that a time is to come when these stones will be held sacred because our hands have touched them, and that men will say, as they look upon the labor and wrought substance of them, "See! This our fathers did for us."
            John Ruskin (1819 - 1900)

            Comment


            • #7
              Re: Extension Cords

              What gets to me is that they say using 100 feet of 12-3 extension cord is not good, but has anyone ever seen a warning in a power tool instruction manual about Voltage drop related to long runs of building wire?

              100 feet of 12-2 with ground Romex or BX or wires in a conduit is going to have the same Voltage drop as a 100 foot 12 gauge extension cord. This is assuming true wire gauge and good quality copper wire along with good very low resistance connections all the way.

              Plugging in my own 100 foot 12-3 extension cord into a work shop receptacle that's within 2 feet of my main breaker panel and then plugging in a Skil HD-77 worm drive saw into the extension cord for test "A" and then plugging the saw power cord directly into the same receptacle for test "B" only resulted in very minor loss of power from the saw motor. For test "C" I went to my attic where there's a receptacle wired with 14-2 with ground and plugged in the saw. Under that set of conditions and knowing there's a long wire run to the attic, I could tell more difference than with the extension cord. Sometime I will run the above using a good AC Volt meter. I just wanted to do a fast quick test.

              What's really going to matter is the Voltage drop total through all the wire involved.

              Special note: I have actually seen cases of no name imported extension cords with totally B S wire gauge labeling on them. What's said to be X gauge may actually be quite a bit lighter if you cut one end off and actually check the wires inside it.
              Last edited by Old Grunter; 08-07-2008, 10:12 PM.

              Comment


              • #8
                Re: Extension Cords

                Originally posted by Bob D. View Post
                Really, when in series or parallel?


                Originally posted by Bob D. View Post
                I'm gonna hazard a guess that he meant he was going to make two useful 50' foot cords that would be used alone out of the 100' undersized cord.
                That does make sense. I apologize to the OP for my reply.

                Comment


                • #9
                  Re: Extension Cords

                  3mw

                  Do you need a 100 foot extension cord to reach out to where you need to use the saw? Depending on your electrical skills you could connect two of them in parallel and make up a super 100 footer. Before I would start cutting them up, you may want to try selling one or two of them as is provided it is in good condition. Then you can use that $$$ for a super heavy duty 100 foot one as needed.

                  Time I hush up and

                  Comment


                  • #10
                    Re: Extension Cords

                    No, actually I only need about 15-20'. I'm cutting the 100' cord that I already have because I only paid $15 each (clearance price) for them at Sam's Club last year....otherwise I would buy a new 50' cord (10 or 12 gauge). Thanks again guys.

                    Comment


                    • #11
                      Re: Extension Cords

                      You might make one at 25 and one at 75 feet. Both would be handy. The price sure was right for them.

                      Comment


                      • #12
                        Re: Extension Cords

                        Originally posted by Old Grunter View Post
                        You might make one at 25 and one at 75 feet. Both would be handy. The price sure was right for them.
                        OG your plan for 25 + 75 ft extension cords is great but I usually shy away from making my own cords. Do you have a reliable method or favorite replacement polarized plug to use? I will test your suggestion on a good but damaged cord.

                        FYI: ONE local HD was clearing out their 85 ft Husky 12-3 extension cords plus 2 ft tri-plug extension $39>$22 but scanned for $15 and a 25 ft 12-3 cord with 3 receptacles every 8 ft $29>$19
                        Last edited by reConx; 08-09-2008, 11:09 AM.

                        Comment


                        • #13
                          Re: Extension Cords

                          I thought the main motivation for battery operated tools is to address the 100' extension cord phenomenon.

                          Seriously you need to follow the cord/wire size and its limitations. Many bad things can and will happen, such as tool damage, FIRE, electric shock.

                          Aside from a voltage drop across the power cord you can also cause the power tool motor to burn up/fail. In very simple terms think about it as a brown out! Running a high demand current tool on a voltage lower than say 10% can be fatal to the tool as well as undercurrent can cause the motor to burn up.


                          Cactus Man

                          Comment


                          • #14
                            Re: Extension Cords

                            Originally posted by Old Grunter View Post
                            This depends on the Voltage drop they consider to be OK. At 100 feet for a circular saw, I would really recommend using a 10 gauge extension cord. In addition be sure it's on a circuit wired with #12 or #10 wire and has a 20 Amp breaker. The receptacle should not be too far from your load center (breaker panel) of you'll need to figure in the Voltage drop at the receptacle in addition to that of the extension cord. If you have or know someone that has a good AC Voltmeter rig up a good way to measure Voltage at the tool both with it running under load and also with it off. If the drop is over 5% you need heavier wiring. A well made saw can run on as low as 105 Volts as long as you don't work it hard and bog down the motor. If you do need to work it hard be sure there's no less than 112 Volts right where the power cord plugs in and with it under heavy loading. (That's working the saw pretty hard during the Voltage measuring.)

                            If all the above seems confusing, just go with the 10 gauge extension cord and plug it into a receptacle as close as you can to the breaker panel.

                            Are you on a job site, or trying to run tools in your garage?

                            Please note that most (but not all) extension cords and residential receptacles & plugs are rated at no more than 15 Amps. Some super duty 10 gauge extension cords have 20 Amp plugs and connectors on them. This is what you want. Then be sure the receptacle is a 20 Amp rated one too. You can plug in 15 Amp plugs. Please note the T slot.

                            To make this really simple the answer to question 1 is NO. A 12-3 extension cord of 100 feet is not heavy enough for a 15 Amp load. While you can maybe pull it off if you just make a quick cut, then let the saw rest a minute or two and make one quick cut again, you will have a notable loss of power. If you run the saw for long, it will overheat the motor.
                            To: Old Grunter...

                            I've just purchased the Ridgid 8000 watt portable generator for the sole purpose of powering my home for electricity in case of a power failure which seems to be getting more and more frequent nowdays...

                            My question is: This generator came with a 25 ft 30 amp extension cord. BUT, I need 100 feet more. Could I "Piggyback" the 100 ft cord to the 25 ft cord? OR, in doing that would I lose some amps, power, etc....

                            Thanks.....

                            Comment


                            • #15
                              Re: Extension Cords

                              What are you doing that you need a 125' run from the generator? Man, your going to need a huge cable for that run. I'd guess 8 gauge 4 wire- which your going to have a hard time even finding for cable use (most would be for perm. install). I just packed up my 6KW gen. after running for 26 hr. straight while the power was out. How are you planning to use it/tie into your house?

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