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Re: Mill motor trips GFI

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  • Don
    Well, there is one simple reason. My shop is in my garage. The electrical code requires all external outlets, which includes inside a garage, within 4 ft of
    Message 1 of 24 , Nov 6, 2012
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      Well, there is one simple reason. My shop is in my garage. The electrical code requires all external outlets, which includes inside a garage, within 4 ft of ground level to be GFI protected. That is reason one. The other is that short of ripping the roof off the garage, there is no way to install new wiring. I am trapped with the wiring I have. One outlet on each wall, all GFI and they are all common with the three outside the house outlets. It's little things like this that come with houses you didn't build. I have a 10" lathe with a 220V motor that runs on a long extension cord for the unused outlet behind the gas clothes drier. Not ideal, but it allows me to make chips.

      Don

      Don

      --- In taigtools@yahoogroups.com, "Shawn Woolley" <shawnwoolley@...> wrote:
      >
      >
      > Why would you run a tool on a GFI plug it's protect people from shocks in wet conditions. Tools especially with motors load a circuit enough to blow a GFI circuit way to often even if the tool if in perfect condition. I have one GFI plug in my studio only because it's within 6 feet of the sinks other than that everything else is dedicated circuits.
      >
      > --- In taigtools@yahoogroups.com, "Don" <Don@> wrote:
      > >
      > > Guys, with a clearer head, I'm tending to agree that it might be the GFI. It is on a 20amp service, and prior to yesterday, I had run my mill off a 15amp non gfi outlet. I remember a few years back, when I was faceting gemstones, my drain tank for the drip pan filled and when it ran down the side of the jug and hit the floor, it tripped the same GFI. I'll make a trip to the hardware store and pick up a new outlet and we'll see how it goes. I also have a smaller DC motor I can put into the mix and see if it trips the GFI. It wouldn't be from current draw, it's only a 1/8 hp motor, but I could use the same speed control to check it.
      > >
      > > Don
      > >
      > >
      > > --- In taigtools@yahoogroups.com, "juangelt" <juangelt@> wrote:
      > > >
      > > > i think that you should test the motor on a different gfci before tearing into it. just my 2p - it's the 'no regrets' approach.
      > > > gfci do fail.
      > > >
      > > >
      > > > --- In taigtools@yahoogroups.com, "Don" <Don@> wrote:
      > > > >
      > > > > I have a Leeson 1/4HP PM DC motor on my Taig mill and a treadmill speed control. I only have 5 to 10 hours on the motor, it was new when I acquired it. Yesterday, I was using the mill to cut the heads off some rivets in some bed frame angle iron. Out of the blue, my bench shut down. It turned out that it tripped the GFI outlet. I reset it and started the PC and brought up Mach3, turned on the stepper driver power and moved the mill away from the rivet and then started the motor. Just as it was reaching full speed, it tripped the GFI again. I reset the GFI and this time, only started the motor. I slowly increased speed and again, just as it reached full speed, the GFI tripped again.
      > > > >
      > > > > I am guessing that one of the brush wires is shorting to ground, but it seems that would cause a blown fuse in the control. There is no moisture involved, so I'm not getting leakage there tripping the GFI. Any words of wisdom before I pull the motor apart?
      > > > >
      > > > > Don
      > > > >
      > > >
      > >
      >
    • frxdy@aol.com
      I missed some of the postings on this subject so please forgive me if my thoughts have been spoken of before. It seems to me that your motor would be happy if
      Message 2 of 24 , Nov 7, 2012
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        I missed some of the postings on this subject so please forgive me if my
        thoughts have been spoken of before.

        It seems to me that your motor would be happy if it was not on a GFI
        circuit. I can understand how you probably don't want to change the GFI to a
        regular outlet as if the worst occurred the insurance company would go nuts.
        There may be a way to have a normal outlet AND be legal. We all know that
        GFI's are required if an outlet is close to water.... I think closer than 6
        feet to a sink requires a GFI. Well, I quizzed my electrician as to why my
        washing machine does not need a GFI. The answer, he said, is because the
        washing machine has "a dedicated outlet". That is: The washing machine
        outlet has only one plug. Nothing else can be plugged in at the same time.
        So.... perhaps it would be the same for your mill motor. Perhaps the answer is a
        dedicated outlet.




        [Non-text portions of this message have been removed]
      • WAM
        I believe that, according to code, garage outlets must also be on a GFCI...
        Message 3 of 24 , Nov 7, 2012
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          I believe that, according to code, garage outlets must also be on a GFCI...

          frxdy@... wrote:

          >
          >I missed some of the postings on this subject so please forgive me if my
          >thoughts have been spoken of before.
          >
          > It seems to me that your motor would be happy if it was not on a GFI
          >circuit. I can understand how you probably don't want to change the GFI to a
          >regular outlet as if the worst occurred the insurance company would go nuts.
          >There may be a way to have a normal outlet AND be legal. We all know that
          >GFI's are required if an outlet is close to water.... I think closer than 6
          >feet to a sink requires a GFI. Well, I quizzed my electrician as to why my
          >washing machine does not need a GFI. The answer, he said, is because the
          >washing machine has "a dedicated outlet". That is: The washing machine
          >outlet has only one plug. Nothing else can be plugged in at the same time.
          >So.... perhaps it would be the same for your mill motor. Perhaps the answer is a
          > dedicated outlet.
          >
          >
          >
          >
          >[Non-text portions of this message have been removed]
          >
          >
          >
          >
        • Shawn Woolley
          yeah my garage was wired the same way but it also has two dedicated circuits one for a freezer and one for the garage door opener in te ceiling. I had three
          Message 4 of 24 , Nov 7, 2012
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            yeah my garage was wired the same way but it also has two dedicated circuits one for a freezer and one for the garage door opener in te ceiling. I had three extra dedicated circuits put in and to meet code and make life simple mine are all mounted in the walls at about the six foot level not only meeting code but allowing me to have tall workbenches and not have to crawl behind or under them to plug things in. I don't think Ive ever had a home that I didn't change or add circuits to and I was lucky here the electrical panel was on the outside of the garage wall and my loft studio is right above the garage so again it was a easy fix and cost me less than $400 to do all the extra circuits and at least eight plugs three of which are switched and dedicated.

            --- In taigtools@yahoogroups.com, "Don" <Don@...> wrote:
            >
            > Well, there is one simple reason. My shop is in my garage. The electrical code requires all external outlets, which includes inside a garage, within 4 ft of ground level to be GFI protected. That is reason one. The other is that short of ripping the roof off the garage, there is no way to install new wiring. I am trapped with the wiring I have. One outlet on each wall, all GFI and they are all common with the three outside the house outlets. It's little things like this that come with houses you didn't build. I have a 10" lathe with a 220V motor that runs on a long extension cord for the unused outlet behind the gas clothes drier. Not ideal, but it allows me to make chips.
            >
            > Don
            >
            > Don
            >
            > --- In taigtools@yahoogroups.com, "Shawn Woolley" <shawnwoolley@> wrote:
            > >
            > >
            > > Why would you run a tool on a GFI plug it's protect people from shocks in wet conditions. Tools especially with motors load a circuit enough to blow a GFI circuit way to often even if the tool if in perfect condition. I have one GFI plug in my studio only because it's within 6 feet of the sinks other than that everything else is dedicated circuits.
            > >
            > > --- In taigtools@yahoogroups.com, "Don" <Don@> wrote:
            > > >
            > > > Guys, with a clearer head, I'm tending to agree that it might be the GFI. It is on a 20amp service, and prior to yesterday, I had run my mill off a 15amp non gfi outlet. I remember a few years back, when I was faceting gemstones, my drain tank for the drip pan filled and when it ran down the side of the jug and hit the floor, it tripped the same GFI. I'll make a trip to the hardware store and pick up a new outlet and we'll see how it goes. I also have a smaller DC motor I can put into the mix and see if it trips the GFI. It wouldn't be from current draw, it's only a 1/8 hp motor, but I could use the same speed control to check it.
            > > >
            > > > Don
            > > >
            > > >
            > > > --- In taigtools@yahoogroups.com, "juangelt" <juangelt@> wrote:
            > > > >
            > > > > i think that you should test the motor on a different gfci before tearing into it. just my 2p - it's the 'no regrets' approach.
            > > > > gfci do fail.
            > > > >
            > > > >
            > > > > --- In taigtools@yahoogroups.com, "Don" <Don@> wrote:
            > > > > >
            > > > > > I have a Leeson 1/4HP PM DC motor on my Taig mill and a treadmill speed control. I only have 5 to 10 hours on the motor, it was new when I acquired it. Yesterday, I was using the mill to cut the heads off some rivets in some bed frame angle iron. Out of the blue, my bench shut down. It turned out that it tripped the GFI outlet. I reset it and started the PC and brought up Mach3, turned on the stepper driver power and moved the mill away from the rivet and then started the motor. Just as it was reaching full speed, it tripped the GFI again. I reset the GFI and this time, only started the motor. I slowly increased speed and again, just as it reached full speed, the GFI tripped again.
            > > > > >
            > > > > > I am guessing that one of the brush wires is shorting to ground, but it seems that would cause a blown fuse in the control. There is no moisture involved, so I'm not getting leakage there tripping the GFI. Any words of wisdom before I pull the motor apart?
            > > > > >
            > > > > > Don
            > > > > >
            > > > >
            > > >
            > >
            >
          • Joe Brown
            Are you using an extension cord to the mill if so the GFCI will trip. Are you sure that the current used does not exceed the amp rating of the circut ( 15 amp
            Message 5 of 24 , Nov 7, 2012
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              Are you using an extension cord to the mill if so the GFCI will trip. Are you sure that the current used does not exceed the amp rating of the circut
              ( 15 amp vs 20 amp ) . does it trip when cutting or just running without a load.
                                                         Joe


              From: WAM <ajawam2@...>
              To: taigtools@yahoogroups.com
              Sent: Wednesday, November 7, 2012 6:53 AM
              Subject: Re: [taigtools] Re: Mill motor trips GFI

               
              I believe that, according to code, garage outlets must also be on a GFCI...

              mailto:frxdy%40aol.com wrote:

              >
              >I missed some of the postings on this subject so please forgive me if my
              >thoughts have been spoken of before.
              >
              > It seems to me that your motor would be happy if it was not on a GFI
              >circuit. I can understand how you probably don't want to change the GFI to a
              >regular outlet as if the worst occurred the insurance company would go nuts.
              >There may be a way to have a normal outlet AND be legal. We all know that
              >GFI's are required if an outlet is close to water.... I think closer than 6
              >feet to a sink requires a GFI. Well, I quizzed my electrician as to why my
              >washing machine does not need a GFI. The answer, he said, is because the
              >washing machine has "a dedicated outlet". That is: The washing machine
              >outlet has only one plug. Nothing else can be plugged in at the same time.
              >So.... perhaps it would be the same for your mill motor. Perhaps the answer is a
              > dedicated outlet.
              >
              >
              >
              >
              >[Non-text portions of this message have been removed]
              >
              >
              >
              >



              [Non-text portions of this message have been removed]
            • Don
              Everything goes through an extension cord of some sort. I have a 15amp rated power strip and long cord that powers the bench my Mill and mini lathe are on,
              Message 6 of 24 , Nov 7, 2012
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                Everything goes through an extension cord of some sort. I have a 15amp rated power strip and long cord that powers the bench my Mill and mini lathe are on, including the CNC electronics. The GFI is on a 20 amp service. I would be surprised if the bench was drawing more that 10 amps with everything on. My calculations are 7.5 amps.

                I'm curious why you say that an extension cord will cause the GFI to trip.

                In any case, the trip comes with no load on the motor other than the spindle drag and no PC or Steppers powered on. The motor alone would draw less than 2 amps under load.

                Don



                --- In taigtools@yahoogroups.com, Joe Brown <jb34742000@...> wrote:
                >
                > Are you using an extension cord to the mill if so the GFCI will trip. Are you sure that the current used does not exceed the amp rating of the circut
                > ( 15 amp vs 20 amp ) . does it trip when cutting or just running without a load.
                >                                            Joe
                >
                >
                > From: WAM <ajawam2@...>
                > To: taigtools@yahoogroups.com
                > Sent: Wednesday, November 7, 2012 6:53 AM
                > Subject: Re: [taigtools] Re: Mill motor trips GFI
                >
                >  
                > I believe that, according to code, garage outlets must also be on a GFCI...
                >
                > mailto:frxdy%40aol.com wrote:
                >
                > >
                > >I missed some of the postings on this subject so please forgive me if my
                > >thoughts have been spoken of before.
                > >
                > > It seems to me that your motor would be happy if it was not on a GFI
                > >circuit. I can understand how you probably don't want to change the GFI to a
                > >regular outlet as if the worst occurred the insurance company would go nuts.
                > >There may be a way to have a normal outlet AND be legal. We all know that
                > >GFI's are required if an outlet is close to water.... I think closer than 6
                > >feet to a sink requires a GFI. Well, I quizzed my electrician as to why my
                > >washing machine does not need a GFI. The answer, he said, is because the
                > >washing machine has "a dedicated outlet". That is: The washing machine
                > >outlet has only one plug. Nothing else can be plugged in at the same time.
                > >So.... perhaps it would be the same for your mill motor. Perhaps the answer is a
                > > dedicated outlet.
                > >
                > >
                > >
                > >
                > >[Non-text portions of this message have been removed]
                > >
                > >
                > >
                > >
                >
                >
                >
                > [Non-text portions of this message have been removed]
                >
              • Luc
                I m curious why you say that an extension cord will cause the GFI to trip.    Any kind of wire has a resistance in it, the longer it is the smaller it is the
                Message 7 of 24 , Nov 7, 2012
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                  I'm curious why you say that an extension cord will cause the GFI to trip.
                   
                   Any kind of wire has a resistance in it, the longer it is the smaller it is
                  the higher the resistance value will increase creating a current limiter
                  and if long enough will also act as a voltage divider (series circuit)
                  Current limiter is the most common circuit in electronic.
                   
                  hope it did help

                  Luc G 


                  "Being a Master is about having Courage and confidence.
                  Courage to dream something and then....MAKE IT HAPPEN..."


                  ________________________________
                  From: Don <Don@...>
                  To: taigtools@yahoogroups.com
                  Sent: Wednesday, November 7, 2012 12:45:00 PM
                  Subject: [taigtools] Re: Mill motor trips GFI


                   

                  Everything goes through an extension cord of some sort. I have a 15amp rated power strip and long cord that powers the bench my Mill and mini lathe are on, including the CNC electronics. The GFI is on a 20 amp service. I would be surprised if the bench was drawing more that 10 amps with everything on. My calculations are 7.5 amps.

                  I'm curious why you say that an extension cord will cause the GFI to trip.

                  In any case, the trip comes with no load on the motor other than the spindle drag and no PC or Steppers powered on. The motor alone would draw less than 2 amps under load.

                  Don

                  --- In mailto:taigtools%40yahoogroups.com, Joe Brown <jb34742000@...> wrote:
                  >
                  > Are you using an extension cord to the mill if so the GFCI will trip. Are you sure that the current used does not exceed the amp rating of the circut
                  > ( 15 amp vs 20 amp ) . does it trip when cutting or just running without a load.
                  >                                            Joe
                  >
                  >
                  > From: WAM <ajawam2@...>
                  > To: mailto:taigtools%40yahoogroups.com
                  > Sent: Wednesday, November 7, 2012 6:53 AM
                  > Subject: Re: [taigtools] Re: Mill motor trips GFI
                  >
                  >  
                  > I believe that, according to code, garage outlets must also be on a GFCI...
                  >
                  > mailto:frxdy%40aol.com wrote:
                  >
                  > >
                  > >I missed some of the postings on this subject so please forgive me if my
                  > >thoughts have been spoken of before.
                  > >
                  > > It seems to me that your motor would be happy if it was not on a GFI
                  > >circuit. I can understand how you probably don't want to change the GFI to a
                  > >regular outlet as if the worst occurred the insurance company would go nuts.
                  > >There may be a way to have a normal outlet AND be legal. We all know that
                  > >GFI's are required if an outlet is close to water.... I think closer than 6
                  > >feet to a sink requires a GFI. Well, I quizzed my electrician as to why my
                  > >washing machine does not need a GFI. The answer, he said, is because the
                  > >washing machine has "a dedicated outlet". That is: The washing machine
                  > >outlet has only one plug. Nothing else can be plugged in at the same time.
                  > >So.... perhaps it would be the same for your mill motor. Perhaps the answer is a
                  > > dedicated outlet.
                  > >
                  > >
                  > >
                  > >
                  > >[Non-text portions of this message have been removed]
                  > >
                  > >
                  > >
                  > >
                  >
                  >
                  >
                  > [Non-text portions of this message have been removed]
                  >




                  [Non-text portions of this message have been removed]
                • Pierre Coueffin
                  I used to blow breakers from the startup surge on motors when they are on an extension (my portable air compressor was bad for this). If the motor draws say 1
                  Message 8 of 24 , Nov 7, 2012
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                    I used to blow breakers from the startup surge on motors when they are on
                    an extension (my portable air compressor was bad for this). If the motor
                    draws say 1 amp during normal use, it might draw 10 for a split second
                    during startup. P=I*I*R so if the cord has 1 ohm of resistance, during
                    normal use, it dissipates 1*1*1= 1 watt of energy as heat. During startup,
                    the cord dissipates 10*10*1= 100watts of energy. Now scale that for a
                    real-world motor with several amps required to run it, and an actual
                    extension cord that might have 10 ohms of resistance...

                    If you have a 15 amp breaker, it is designed to pop when heated by running
                    about 1900 watts through it. The motor normally draws its startup surge
                    for a fraction of a second (often dimming the lights in a badly wired
                    house) then drops the load to its running level so fast that the breaker
                    has no time to heat up, and does not pop. Running through a long extension
                    cord, the resistance of the cord makes the motor take longer to spin up,
                    the combined startup load of the motor and the cord is often enough to pop
                    the breaker. Also, the cord will frequently get hot. Warm extension cords
                    are a sure sign of trouble.

                    I have an extension cord that I like now made from 100 feet of heavy cable,
                    I salvaged the 100 amp service cable from a house that was being renovated
                    for 200 amp service. It has both 220 and 110 volt outlets and plugs into
                    the 50 amp 220 volt outlet in the garage. I should really put gfci on it,
                    but I have not. The terminating end is a plywood box with outlets mounted
                    on it. It has a small breaker panel on it, with breakers to limit the
                    current for the 110v outlets to 15 amps, but the long run of heavy cable
                    has no shortage of current available... I've never had a problem running
                    tools from it, anywhere on the yard. If you leave the cable coiled up, it
                    can generate a bit of a magnetic field though. Keep your wallet away from
                    it.


                    [Non-text portions of this message have been removed]
                  • Don
                    When I built my house in New York, I used 12 ga wire for every outlet, and no more than 5 outlets on a breaker. The garage had a 40amp sub panel, with four
                    Message 9 of 24 , Nov 7, 2012
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                      When I built my house in New York, I used 12 ga wire for every outlet, and no more than 5 outlets on a breaker. The garage had a 40amp sub panel, with four services for outlets. One every six foot. My basement had two sub panels, one supplied the well pump, furnaces, oil fired hot water heater, and the refrigerator in the kitchen. That panel had a pig tail input so I could cut over the heat, water, and refrigerator to generator power. The other 40 amp sub was for my shop I was just starting on when I got transferred out here to California. My first house here had a crawl space so I could get at the wiring without to much problem. This house though is on a slab, so everything goes through the attic. The attic is all trust, with vaulted ceilings for the most part. There is 18" of insulation, so trying to get up there to do any wiring is difficult to impossible. The Garage is all sheet rocked in and all wiring to the house goes over the garage ceiling. The main panel is on the outside wall of the garage, but there are cabinets in the garage on that wall so I would have to remove them, and cut into the attic of the garage to run more wiring. Or put in conduit along the floor. That would only allow extra outlets on the same wall the panel is on though at there are two doors in the back of the garage that prevents making a bend around the corner. I have accepted that I need a good set of 14ga and 12 ga extension cords and I get to trip over them when I'm working. If I hit the lotto, then I'll get a house with a proper shop wired as I want.

                      Don

                      --- In taigtools@yahoogroups.com, "Shawn Woolley" <shawnwoolley@...> wrote:
                      >
                      > yeah my garage was wired the same way but it also has two dedicated circuits one for a freezer and one for the garage door opener in te ceiling. I had three extra dedicated circuits put in and to meet code and make life simple mine are all mounted in the walls at about the six foot level not only meeting code but allowing me to have tall workbenches and not have to crawl behind or under them to plug things in. I don't think Ive ever had a home that I didn't change or add circuits to and I was lucky here the electrical panel was on the outside of the garage wall and my loft studio is right above the garage so again it was a easy fix and cost me less than $400 to do all the extra circuits and at least eight plugs three of which are switched and dedicated.
                      >
                      > --- In taigtools@yahoogroups.com, "Don" <Don@> wrote:
                      > >
                      > > Well, there is one simple reason. My shop is in my garage. The electrical code requires all external outlets, which includes inside a garage, within 4 ft of ground level to be GFI protected. That is reason one. The other is that short of ripping the roof off the garage, there is no way to install new wiring. I am trapped with the wiring I have. One outlet on each wall, all GFI and they are all common with the three outside the house outlets. It's little things like this that come with houses you didn't build. I have a 10" lathe with a 220V motor that runs on a long extension cord for the unused outlet behind the gas clothes drier. Not ideal, but it allows me to make chips.
                      > >
                      > > Don
                      > >
                      > > Don
                      > >
                      > > --- In taigtools@yahoogroups.com, "Shawn Woolley" <shawnwoolley@> wrote:
                      > > >
                      > > >
                      > > > Why would you run a tool on a GFI plug it's protect people from shocks in wet conditions. Tools especially with motors load a circuit enough to blow a GFI circuit way to often even if the tool if in perfect condition. I have one GFI plug in my studio only because it's within 6 feet of the sinks other than that everything else is dedicated circuits.
                      > > >
                      > > > --- In taigtools@yahoogroups.com, "Don" <Don@> wrote:
                      > > > >
                      > > > > Guys, with a clearer head, I'm tending to agree that it might be the GFI. It is on a 20amp service, and prior to yesterday, I had run my mill off a 15amp non gfi outlet. I remember a few years back, when I was faceting gemstones, my drain tank for the drip pan filled and when it ran down the side of the jug and hit the floor, it tripped the same GFI. I'll make a trip to the hardware store and pick up a new outlet and we'll see how it goes. I also have a smaller DC motor I can put into the mix and see if it trips the GFI. It wouldn't be from current draw, it's only a 1/8 hp motor, but I could use the same speed control to check it.
                      > > > >
                      > > > > Don
                      > > > >
                      > > > >
                      > > > > --- In taigtools@yahoogroups.com, "juangelt" <juangelt@> wrote:
                      > > > > >
                      > > > > > i think that you should test the motor on a different gfci before tearing into it. just my 2p - it's the 'no regrets' approach.
                      > > > > > gfci do fail.
                      > > > > >
                      > > > > >
                      > > > > > --- In taigtools@yahoogroups.com, "Don" <Don@> wrote:
                      > > > > > >
                      > > > > > > I have a Leeson 1/4HP PM DC motor on my Taig mill and a treadmill speed control. I only have 5 to 10 hours on the motor, it was new when I acquired it. Yesterday, I was using the mill to cut the heads off some rivets in some bed frame angle iron. Out of the blue, my bench shut down. It turned out that it tripped the GFI outlet. I reset it and started the PC and brought up Mach3, turned on the stepper driver power and moved the mill away from the rivet and then started the motor. Just as it was reaching full speed, it tripped the GFI again. I reset the GFI and this time, only started the motor. I slowly increased speed and again, just as it reached full speed, the GFI tripped again.
                      > > > > > >
                      > > > > > > I am guessing that one of the brush wires is shorting to ground, but it seems that would cause a blown fuse in the control. There is no moisture involved, so I'm not getting leakage there tripping the GFI. Any words of wisdom before I pull the motor apart?
                      > > > > > >
                      > > > > > > Don
                      > > > > > >
                      > > > > >
                      > > > >
                      > > >
                      > >
                      >
                    • Pierre Coueffin
                      Have you considered hanging the extension cords from the ceiling? I did that with electricity and air lines in the garage of one house I lived in, and it
                      Message 10 of 24 , Nov 7, 2012
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                        Have you considered hanging the extension cords from the ceiling? I did
                        that with electricity and air lines in the garage of one house I lived in,
                        and it saved me considerable frustration. A few strategically placed
                        hooks makes for a much less hazardous floor space.



                        On Wed, Nov 7, 2012 at 12:28 PM, Don <Don@...> wrote:

                        > I have accepted that I need a good set of 14ga and 12 ga extension cords
                        > and I get to trip over them when I'm working.
                        >


                        [Non-text portions of this message have been removed]
                      • Joe Brown
                        Extension cords used with motors will quite often cause a GFI to trip. The reason is the additional end plugs prongs, will not provide a sound connection for
                        Message 11 of 24 , Nov 7, 2012
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                          Extension cords used with motors will quite often cause a GFI to trip. The reason is the additional end plugs prongs, will not provide a sound connection for the neutral wire or the hot wire, and most of all the ground prong which slips into connector in the extension cord is a poor connection especially when the GFCI is sensing for a ground interruption.
                          If you measure with a voltmeter, you will not indicate any changes, using an oscilloscope will show any unbalance in the line. Motors can also leak electricity in to their motor housings. If the electricity is not returning through it's designed path then you may have a safety hazard and your GFCI is protecting you.
                           



                          From: Luc <salutluc2004@...>
                          To: "taigtools@yahoogroups.com" <taigtools@yahoogroups.com>
                          Sent: Wednesday, November 7, 2012 12:54 PM
                          Subject: Re: [taigtools] Re: Mill motor trips GFI

                           
                          I'm curious why you say that an extension cord will cause the GFI to trip.
                           
                           Any kind of wire has a resistance in it, the longer it is the smaller it is
                          the higher the resistance value will increase creating a current limiter
                          and if long enough will also act as a voltage divider (series circuit)
                          Current limiter is the most common circuit in electronic.
                           
                          hope it did help

                          Luc G 

                          "Being a Master is about having Courage and confidence.
                          Courage to dream something and then....MAKE IT HAPPEN..."


                          ________________________________
                          From: Don <mailto:Don%40Campbell-Gemstones.com>
                          To: mailto:taigtools%40yahoogroups.com
                          Sent: Wednesday, November 7, 2012 12:45:00 PM
                          Subject: [taigtools] Re: Mill motor trips GFI


                           

                          Everything goes through an extension cord of some sort. I have a 15amp rated power strip and long cord that powers the bench my Mill and mini lathe are on, including the CNC electronics. The GFI is on a 20 amp service. I would be surprised if the bench was drawing more that 10 amps with everything on. My calculations are 7.5 amps.

                          I'm curious why you say that an extension cord will cause the GFI to trip.

                          In any case, the trip comes with no load on the motor other than the spindle drag and no PC or Steppers powered on. The motor alone would draw less than 2 amps under load.

                          Don

                          --- In mailto:taigtools%40yahoogroups.com, Joe Brown <jb34742000@...> wrote:
                          >
                          > Are you using an extension cord to the mill if so the GFCI will trip. Are you sure that the current used does not exceed the amp rating of the circut
                          > ( 15 amp vs 20 amp ) . does it trip when cutting or just running without a load.
                          >                                            Joe
                          >
                          >
                          > From: WAM <ajawam2@...>
                          > To: mailto:taigtools%40yahoogroups.com
                          > Sent: Wednesday, November 7, 2012 6:53 AM
                          > Subject: Re: [taigtools] Re: Mill motor trips GFI
                          >
                          >  
                          > I believe that, according to code, garage outlets must also be on a GFCI...
                          >
                          > mailto:frxdy%40aol.com wrote:
                          >
                          > >
                          > >I missed some of the postings on this subject so please forgive me if my
                          > >thoughts have been spoken of before.
                          > >
                          > > It seems to me that your motor would be happy if it was not on a GFI
                          > >circuit. I can understand how you probably don't want to change the GFI to a
                          > >regular outlet as if the worst occurred the insurance company would go nuts.
                          > >There may be a way to have a normal outlet AND be legal. We all know that
                          > >GFI's are required if an outlet is close to water.... I think closer than 6
                          > >feet to a sink requires a GFI. Well, I quizzed my electrician as to why my
                          > >washing machine does not need a GFI. The answer, he said, is because the
                          > >washing machine has "a dedicated outlet". That is: The washing machine
                          > >outlet has only one plug. Nothing else can be plugged in at the same time.
                          > >So.... perhaps it would be the same for your mill motor. Perhaps the answer is a
                          > > dedicated outlet.
                          > >
                          > >
                          > >
                          > >
                          > >[Non-text portions of this message have been removed]
                          > >
                          > >
                          > >
                          > >
                          >
                          >
                          >
                          > [Non-text portions of this message have been removed]
                          >

                          [Non-text portions of this message have been removed]




                          [Non-text portions of this message have been removed]
                        • Don
                          OK,that sounds like a logical explanation. The problem is probably more severe when under size extension cords are used also. The voltage drop on a long under
                          Message 12 of 24 , Nov 7, 2012
                          • 0 Attachment
                            OK,that sounds like a logical explanation. The problem is probably more severe when under size extension cords are used also. The voltage drop on a long under sized cord can be significant. A few years back, I was helping my daughter and son-in-law rebuild their house. He had borrowed a neighbors little pancake compressor and it kept tripping a circuit breaker. If we used a cord over 25 ft long, it would trip the breaker. The cords he had were little 16ga wires I brought up a 14ga 50 ft cord the next weekend and that put an end to the tripped breakers. I guess a high resistance contact between a plug and socket could also cause a significant voltage drop.

                            Don

                            --- In taigtools@yahoogroups.com, Joe Brown <jb34742000@...> wrote:
                            >
                            > Extension cords used with motors will quite often cause a GFI to trip. The reason is the additional end plugs prongs, will not provide a sound connection for the neutral wire or the hot wire, and most of all the ground prong which slips into connector in the extension cord is a poor connection especially when the GFCI is sensing for a ground interruption.
                            > If you measure with a voltmeter, you will not indicate any changes, using an oscilloscope will show any unbalance in the line. Motors can also leak electricity in to their motor housings. If the electricity is not returning through it's designed path then you may have a safety hazard and your GFCI is protecting you.
                            >  
                            >
                            >
                            >
                            > From: Luc <salutluc2004@...>
                            > To: "taigtools@yahoogroups.com" <taigtools@yahoogroups.com>
                            > Sent: Wednesday, November 7, 2012 12:54 PM
                            > Subject: Re: [taigtools] Re: Mill motor trips GFI
                            >
                            >  
                            > I'm curious why you say that an extension cord will cause the GFI to trip.
                            >  
                            >  Any kind of wire has a resistance in it, the longer it is the smaller it is
                            > the higher the resistance value will increase creating a current limiter
                            > and if long enough will also act as a voltage divider (series circuit)
                            > Current limiter is the most common circuit in electronic.
                            >  
                            > hope it did help
                            >
                            > Luc G 
                            >
                            > "Being a Master is about having Courage and confidence.
                            > Courage to dream something and then....MAKE IT HAPPEN..."
                            >
                            >
                            > ________________________________
                            > From: Don <mailto:Don%40Campbell-Gemstones.com>
                            > To: mailto:taigtools%40yahoogroups.com
                            > Sent: Wednesday, November 7, 2012 12:45:00 PM
                            > Subject: [taigtools] Re: Mill motor trips GFI
                            >
                            >
                            >  
                            >
                            > Everything goes through an extension cord of some sort. I have a 15amp rated power strip and long cord that powers the bench my Mill and mini lathe are on, including the CNC electronics. The GFI is on a 20 amp service. I would be surprised if the bench was drawing more that 10 amps with everything on. My calculations are 7.5 amps.
                            >
                            > I'm curious why you say that an extension cord will cause the GFI to trip.
                            >
                            > In any case, the trip comes with no load on the motor other than the spindle drag and no PC or Steppers powered on. The motor alone would draw less than 2 amps under load.
                            >
                            > Don
                            >
                            > --- In mailto:taigtools%40yahoogroups.com, Joe Brown <jb34742000@> wrote:
                            > >
                            > > Are you using an extension cord to the mill if so the GFCI will trip. Are you sure that the current used does not exceed the amp rating of the circut
                            > > ( 15 amp vs 20 amp ) . does it trip when cutting or just running without a load.
                            > >                                            Joe
                            > >
                            > >
                            > > From: WAM <ajawam2@>
                            > > To: mailto:taigtools%40yahoogroups.com
                            > > Sent: Wednesday, November 7, 2012 6:53 AM
                            > > Subject: Re: [taigtools] Re: Mill motor trips GFI
                            > >
                            > >  
                            > > I believe that, according to code, garage outlets must also be on a GFCI...
                            > >
                            > > mailto:frxdy%40aol.com wrote:
                            > >
                            > > >
                            > > >I missed some of the postings on this subject so please forgive me if my
                            > > >thoughts have been spoken of before.
                            > > >
                            > > > It seems to me that your motor would be happy if it was not on a GFI
                            > > >circuit. I can understand how you probably don't want to change the GFI to a
                            > > >regular outlet as if the worst occurred the insurance company would go nuts.
                            > > >There may be a way to have a normal outlet AND be legal. We all know that
                            > > >GFI's are required if an outlet is close to water.... I think closer than 6
                            > > >feet to a sink requires a GFI. Well, I quizzed my electrician as to why my
                            > > >washing machine does not need a GFI. The answer, he said, is because the
                            > > >washing machine has "a dedicated outlet". That is: The washing machine
                            > > >outlet has only one plug. Nothing else can be plugged in at the same time.
                            > > >So.... perhaps it would be the same for your mill motor. Perhaps the answer is a
                            > > > dedicated outlet.
                            > > >
                            > > >
                            > > >
                            > > >
                            > > >[Non-text portions of this message have been removed]
                            > > >
                            > > >
                            > > >
                            > > >
                            > >
                            > >
                            > >
                            > > [Non-text portions of this message have been removed]
                            > >
                            >
                            > [Non-text portions of this message have been removed]
                            >
                            >
                            >
                            >
                            > [Non-text portions of this message have been removed]
                            >
                          • Shawn Woolley
                            Totally agree I have plugs in my cieling right now in both my studio and in garage. I had a electrician but the circuits in and each one has a short pigtail
                            Message 13 of 24 , Nov 7, 2012
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                              Totally agree I have plugs in my cieling right now in both my studio and in garage. I had a electrician but the circuits in and each one has a short pigtail hanging from the ceiling that put's these plugs at about 6'6" above the ground that way nobody get's whacked in the head and I don't spend all my time tripping over cords or crawling under benches. The wall plugs I added are also about 6 foot above the floor again no requirements for water or GFI and keeps the tool cords neatly organized and easy to move rathe than snaked all over the desktop or hanging under benches to tangle with my feet.


                              --- In taigtools@yahoogroups.com, Pierre Coueffin <pcoueffin@...> wrote:
                              >
                              > Have you considered hanging the extension cords from the ceiling? I did
                              > that with electricity and air lines in the garage of one house I lived in,
                              > and it saved me considerable frustration. A few strategically placed
                              > hooks makes for a much less hazardous floor space.
                              >
                              >
                              >
                              > On Wed, Nov 7, 2012 at 12:28 PM, Don <Don@...> wrote:
                              >
                              > > I have accepted that I need a good set of 14ga and 12 ga extension cords
                              > > and I get to trip over them when I'm working.
                              > >
                              >
                              >
                              > [Non-text portions of this message have been removed]
                              >
                            • Paul J. Ste. Marie
                              ... It shouldn t, unless the cord is defective or there s moisture on the connection. GFCI s are by design quite finicky about current leaks. I run my mill on
                              Message 14 of 24 , Nov 9, 2012
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                                On 11/7/2012 4:27 AM, Joe Brown wrote:
                                > Are you using an extension cord to the mill if so the GFCI will trip.

                                It shouldn't, unless the cord is defective or there's moisture on the
                                connection. GFCI's are by design quite finicky about current leaks.

                                I run my mill on an extension cord in a GFCI all the time. No problems,
                                but the connection is up on the workbench, not on the floor.
                              • Paul J. Ste. Marie
                                ... And? Yes, there s a voltage drop in the wire, and the resistance would eventually limit the current. Neither effect is noticeable if you re using a cord
                                Message 15 of 24 , Nov 9, 2012
                                • 0 Attachment
                                  On 11/7/2012 9:54 AM, Luc wrote:
                                  > Any kind of wire has a resistance in it, the longer it is the smaller
                                  > it is the higher the resistance value will increase creating a
                                  > current limiter and if long enough will also act as a voltage divider
                                  > (series circuit)

                                  And? Yes, there's a voltage drop in the wire, and the resistance would
                                  eventually limit the current. Neither effect is noticeable if you're
                                  using a cord even close to the required size.

                                  GFCIs measure the difference in current going through the line and the
                                  neutral. As long as those two currents are equal and opposite, it's
                                  happy. If there's a difference, e.g. some current is going though
                                  moisture in a plug or a chunk of meat to ground, then they trip.
                                  Conceptually you could have a large capacitance to ground that current
                                  in a strictly A/C sense is going through, but not terribly likely.

                                  A breaker tripping from a startup surge is a different matter.

                                  Joe wrote:
                                  > most of all the ground prong which slips into connector in the
                                  > extension cord is a poor connection especially when the GFCI is
                                  > sensing for a ground interruption.

                                  A GFCI doesn't do anything with the ground. There should be no current
                                  flowing through the ground, which is indistinguishable from a open ground.

                                  It's just an accountant. Current out the line must equal current back
                                  in the neutral.
                                • Paul J. Ste. Marie
                                  ... A GFCI will trip on a tiny fraction of what a circuit breaker requires. Blowing a break requires 12 ohms or less to ground. A GFCI will trip on 24,000
                                  Message 16 of 24 , Nov 9, 2012
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                                    On 11/6/2012 9:02 AM, Don wrote:
                                    > I am guessing that one of the brush wires is shorting to ground, but
                                    > it seems that would cause a blown fuse in the control. There is no
                                    > moisture involved, so I'm not getting leakage there tripping the GFI.
                                    > Any words of wisdom before I pull the motor apart?

                                    A GFCI will trip on a tiny fraction of what a circuit breaker requires.
                                    Blowing a break requires 12 ohms or less to ground. A GFCI will trip
                                    on 24,000 ohms to ground. Could be bad insulation on a wire shifting
                                    when you come up to full RPM, or possibly carbon dust from the brushes
                                  • WAM
                                    One thing I came across in my hardware lab: http://home.comcast.net/~ajawamnet/wc/image002.jpg ...when I was adding these nice wall mount 5 power outlet
                                    Message 17 of 24 , Nov 9, 2012
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                                      One thing I came across in my hardware lab:
                                      http://home.comcast.net/~ajawamnet/wc/image002.jpg
                                      ...when I was adding these nice wall mount 5' power outlet strips from
                                      Lowes - If you have enough of them on a GFCI they'll trip.

                                      Why?

                                      Someone decided that it'd be a good I dea to see if the ground was OK
                                      using an LED. Great idea in theory, depends on how you do it..

                                      Plugged in three of these. Pow... GFCI tripped. I was like WTH?

                                      I bought a zillion of these (my project manager was drooling over them
                                      when they were waiting to be installed)...

                                      So I dissassembled it ... what'd Utilitech do (Lowes house brand)?

                                      Added an LED and cap/dropping resistor between the hot and safety
                                      ground. Lovely...

                                      So I did some experiments; taking my scope, a specail GF cord I made,
                                      and some other crap over to Lowes for "science day" ( the guys over at
                                      the Manassas Lowes love it - science day 1 was my Tek spectrum sniffing
                                      nasty LED lamps ( vid of one here -
                                      http://www.youtube.com/watch?v=xB9BTSgTRY0 - just a scanner anntena, no
                                      preamp )

                                      Sure enough, all of the newer strips that have a "ground good" LED
                                      dumping a few mA of current into the ground. If you actually lift the
                                      ground (what the GF lift was used for ) you can see a nice 60-80VAC on
                                      the case of the strip to the building ground.

                                      Awesome....

                                      GFCI - http://www.elec-toolbox.com/Safety/fig1-22.gif

                                      As long as current in the CT in the GFCI balances between line and
                                      neutral you're OK. Story i was told was that the guy that designed it
                                      had someone throw a radio into a pool he was in that was plugged into
                                      one of his prototypes ... not sure if that's an urban legend or not.



                                      Paul J. Ste. Marie wrote:

                                      >On 11/6/2012 9:02 AM, Don wrote:
                                      >
                                      >
                                      >>I am guessing that one of the brush wires is shorting to ground, but
                                      >>it seems that would cause a blown fuse in the control. There is no
                                      >>moisture involved, so I'm not getting leakage there tripping the GFI.
                                      >>Any words of wisdom before I pull the motor apart?
                                      >>
                                      >>
                                      >
                                      >A GFCI will trip on a tiny fraction of what a circuit breaker requires.
                                      > Blowing a break requires 12 ohms or less to ground. A GFCI will trip
                                      >on 24,000 ohms to ground. Could be bad insulation on a wire shifting
                                      >when you come up to full RPM, or possibly carbon dust from the brushes
                                      >
                                      >
                                      >


                                      [Non-text portions of this message have been removed]
                                    • Don
                                      There has been a number of good leads pointed out. I have resolved the issue, a work around but not a fix. I got a long extension cord and plugged into the
                                      Message 18 of 24 , Nov 9, 2012
                                      • 0 Attachment
                                        There has been a number of good leads pointed out. I have resolved the issue, a work around but not a fix. I got a long extension cord and plugged into the Central Vacuum outlet on the other side of the garage. I'll do some component swapping, IE the speed controller later. I have been chomping at the bit to get my Er-20 head stock finished and I need the mill to accurately locate a hole.

                                        Now that the headstock is complete, I'll get back to the GFI trip.

                                        Don

                                        --- In taigtools@yahoogroups.com, WAM <ajawam2@...> wrote:
                                        >
                                        > One thing I came across in my hardware lab:
                                        > http://home.comcast.net/~ajawamnet/wc/image002.jpg
                                        > ...when I was adding these nice wall mount 5' power outlet strips from
                                        > Lowes - If you have enough of them on a GFCI they'll trip.
                                        >
                                        > Why?
                                        >
                                        > Someone decided that it'd be a good I dea to see if the ground was OK
                                        > using an LED. Great idea in theory, depends on how you do it..
                                        >
                                        > Plugged in three of these. Pow... GFCI tripped. I was like WTH?
                                        >
                                        > I bought a zillion of these (my project manager was drooling over them
                                        > when they were waiting to be installed)...
                                        >
                                        > So I dissassembled it ... what'd Utilitech do (Lowes house brand)?
                                        >
                                        > Added an LED and cap/dropping resistor between the hot and safety
                                        > ground. Lovely...
                                        >
                                        > So I did some experiments; taking my scope, a specail GF cord I made,
                                        > and some other crap over to Lowes for "science day" ( the guys over at
                                        > the Manassas Lowes love it - science day 1 was my Tek spectrum sniffing
                                        > nasty LED lamps ( vid of one here -
                                        > http://www.youtube.com/watch?v=xB9BTSgTRY0 - just a scanner anntena, no
                                        > preamp )
                                        >
                                        > Sure enough, all of the newer strips that have a "ground good" LED
                                        > dumping a few mA of current into the ground. If you actually lift the
                                        > ground (what the GF lift was used for ) you can see a nice 60-80VAC on
                                        > the case of the strip to the building ground.
                                        >
                                        > Awesome....
                                        >
                                        > GFCI - http://www.elec-toolbox.com/Safety/fig1-22.gif
                                        >
                                        > As long as current in the CT in the GFCI balances between line and
                                        > neutral you're OK. Story i was told was that the guy that designed it
                                        > had someone throw a radio into a pool he was in that was plugged into
                                        > one of his prototypes ... not sure if that's an urban legend or not.
                                        >
                                        >
                                        >
                                        > Paul J. Ste. Marie wrote:
                                        >
                                        > >On 11/6/2012 9:02 AM, Don wrote:
                                        > >
                                        > >
                                        > >>I am guessing that one of the brush wires is shorting to ground, but
                                        > >>it seems that would cause a blown fuse in the control. There is no
                                        > >>moisture involved, so I'm not getting leakage there tripping the GFI.
                                        > >>Any words of wisdom before I pull the motor apart?
                                        > >>
                                        > >>
                                        > >
                                        > >A GFCI will trip on a tiny fraction of what a circuit breaker requires.
                                        > > Blowing a break requires 12 ohms or less to ground. A GFCI will trip
                                        > >on 24,000 ohms to ground. Could be bad insulation on a wire shifting
                                        > >when you come up to full RPM, or possibly carbon dust from the brushes
                                        > >
                                        > >
                                        > >
                                        >
                                        >
                                        > [Non-text portions of this message have been removed]
                                        >
                                      • Paul J. Ste. Marie
                                        ... ROFL. I m surprised/dismayed your GFCI doesn t trip on just one of those. Usual indicator LED currents are 10-20 mA. Incompetent twits. That s up that
                                        Message 19 of 24 , Nov 12, 2012
                                        • 0 Attachment
                                          On 11/9/2012 10:25 AM, WAM wrote:
                                          > ...when I was adding these nice wall mount 5' power outlet strips from
                                          > Lowes - If you have enough of them on a GFCI they'll trip.
                                          >
                                          > Why?
                                          >
                                          > Someone decided that it'd be a good I dea to see if the ground was OK
                                          > using an LED. Great idea in theory, depends on how you do it..

                                          ROFL. I'm surprised/dismayed your GFCI doesn't trip on just one of
                                          those. Usual indicator LED currents are 10-20 mA.

                                          Incompetent twits. That's up that with an clock-radio I took apart to
                                          fix and discovered that instead of a transformer, it just had a big
                                          power resistor to drop the line current.
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