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Re: [SeattleRobotics] "Safety Earth Connection"

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  • David Buckley
    Tom I don t really see what the plastic box has to do with anything, either exposed metal bits are connected to Ground or they are not. Never should they be
    Message 1 of 12 , Aug 15, 2012
      Tom
      I don't really see what the plastic box has to do with anything, either exposed metal bits are connected to Ground or they are not. Never should they be connected to Neutral for just the case of bad wiring you mentioned.
      Isolated does not mean the same as Grounded/Earthed. Isolated means not connected to anything.
      You might find if you isolate the trace and then Ground the screws that the 0v output line might not be at Earth potential, remember what I said about the Japanese printer.
      There is no doubt some reason for it being the way it is. The sensible thing would be to follow the instructions on the PSU and connect it to Ground the way it tells you to.
      DAvid
       
       
      ----- Original Message -----
      Sent: Thursday, August 16, 2012 1:18 AM
      Subject: Re: [SeattleRobotics] "Safety Earth Connection"

       

      Thanks, Dave,
           I've received two replies and the only reason that I asked about "neutral' as opposed to "ground" is from what I read on "Google."  I have wired many household type circuits and certainly know what the Black / white / and green or copper wires are, as well as the new types of 125/250 VAC receptacles that are on almost all electronic equipment.  I know that the central, longer flat blade is the ground.  My question was generated by my use of a plastic box as the case.  I'll have a small fan inside, but, I didn't want a 'hot' or floating ground on the one of four metal mounting screws on the plastic box, which might occur if the neutral in some plug I happened to use was mis-wired and was 'hot.' What I'll do is isolate that circular trace and just run it directly to the "ground" (central pin) on my power receptacle on the back of the PS box.  All four screws will be isolated.
           Thanks for the info Dave & wiml@...,
           Tom C.
       
      In a message dated 8/15/2012 5:04:31 P.M. Pacific Daylight Time, dhylands@... writes:


      Hi,

      On Wed, Aug 15, 2012 at 4:55 PM, Dan Tebbs <dantebbs@...> wrote:


      Yes Tom,

      That does indeed mean the 'neutral' line. On U.S. power cords, that is the round one as opposed to the two blades.

      So there seems to be some confusing teminology.

      If you pull an electrical wire (Romex) from your wall and open it up, you'll find a black wire, a white wire, and a bare copper wire.

      In electrician's terms, the black wire is hot, the white wire is neutral, and the bare copper wire is ground.

      neutral and ground are connected together at your electrical panel.

      Here's a picture which identifies the corresponding positions on your typical US electrical outlet:
      http://www.homemaintenancereminder.com/articles_openground.htm.

      The frame ground on your power supply should be connected to the ground (round pin)

      --
      Dave Hylands
      Shuswap, BC, Canada
      http://www.davehylands.com

    • Dave Hylands
      Hi Tom, ... I m assuming you meant the central longer rounded blade is ground. The flat blades are either hot or neutral. Just being picky here because we re
      Message 2 of 12 , Aug 15, 2012
        Hi Tom,

        On Wed, Aug 15, 2012 at 5:18 PM, <twcarroll@...> wrote:


        Thanks, Dave,
             I've received two replies and the only reason that I asked about "neutral' as opposed to "ground" is from what I read on "Google."  I have wired many household type circuits and certainly know what the Black / white / and green or copper wires are, as well as the new types of 125/250 VAC receptacles that are on almost all electronic equipment.  I know that the central, longer flat blade is the ground. 

        I'm assuming you meant the central longer rounded blade is ground. The flat blades are either hot or neutral. Just being picky here because we're talking about 120v.
         
        My question was generated by my use of a plastic box as the case.  I'll have a small fan inside, but, I didn't want a 'hot' or floating ground on the one of four metal mounting screws on the plastic box, which might occur if the neutral in some plug I happened to use was mis-wired and was 'hot.' What I'll do is isolate that circular trace and just run it directly to the "ground" (central pin) on my power receptacle on the back of the PS box.  All four screws will be isolated.

        So yeah, anything touchable on the outside should be electrically connected to ground, and not to neutral.
         
        --
        Dave Hylands
        Shuswap, BC, Canada
        http://www.davehylands.com
      • twcarroll@aol.com
        Dave, DAvid and others, No, I actually stated that the longer central blade is actually a blade and not a longer round pin like in a typical plug. The
        Message 3 of 12 , Aug 15, 2012
          Dave, DAvid and others,
               No, I actually stated that the longer central blade is actually a 'blade' and not a longer round pin like in a typical plug.  The typical grounding 'pin' in a three conductor grounded male plug is a piece of rounded brass stock, formed into a 1/8" diameter pin that goes into the lower (or upper- depending how your female socket is oriented) central ground female 'hole.' 
               What I am referring to is NOT a plug that you insert into a wall socket but the male three pin receptacle in the back of most newer electronic equipment.  It has three flat pine with the lower central flat pin the ground pin.  These are the receptacles that are basically a rounded rectangle shape with the two lower sides at 45 degree angles.  I know you realize what I am referring to.  Your flat screen TV, cable box, newer oscilloscope and so many items use this type of plug / receptacle for your removable power cord,- the other end of which has the three male pins,- two flat and a longer round brass ground pin.  It is this type of male receptacle that I am installing into the plastic box containing the power supply, fan and a terminal strip,- with red and black female banana connections on the outside for the different fixed voltages.  I have worked with all sorts of voltages all my life and know how to be safe and how to ground things.
               Tom C
          I'm assuming you meant the central longer rounded blade is ground. The flat blades are either hot or neutral. Just being picky here because we're talking about 120v.
        • Dave Hylands
          Hi Tom, ... Ok - I know what you re talking about now. One off these: http://media.digikey.com/Photos/Qualtek%20Photos/703W-00%5E07.jpg (the old adage of a
          Message 4 of 12 , Aug 15, 2012
            Hi Tom,

            On Wed, Aug 15, 2012 at 9:51 PM, <twcarroll@...> wrote:


            Dave, DAvid and others,
                 No, I actually stated that the longer central blade is actually a 'blade' and not a longer round pin like in a typical plug.  The typical grounding 'pin' in a three conductor grounded male plug is a piece of rounded brass stock, formed into a 1/8" diameter pin that goes into the lower (or upper- depending how your female socket is oriented) central ground female 'hole.' 
                 What I am referring to is NOT a plug that you insert into a wall socket but the male three pin receptacle in the back of most newer electronic equipment.  It has three flat pine with the lower central flat pin the ground pin.  These are the receptacles that are basically a rounded rectangle shape with the two lower sides at 45 degree angles.  I know you realize what I am referring to.  Your flat screen TV, cable box, newer oscilloscope and so many items use this type of plug / receptacle for your removable power cord,- the other end of which has the three male pins,- two flat and a longer round brass ground pin.  It is this type of male receptacle that I am installing into the plastic box containing the power supply, fan and a terminal strip,- with red and black female banana connections on the outside for the different fixed voltages.  I have worked with all sorts of voltages all my life and know how to be safe and how to ground things.

            Ok - I know what you're talking about now.

            One off these: http://media.digikey.com/Photos/Qualtek%20Photos/703W-00%5E07.jpg (the old adage of a picture is worth a thousand words springs to mind).

            For some reason I was fixated on the part that plugs into the wall - Doh.

            --
            Dave Hylands
            Shuswap, BC, Canada
            http://www.davehylands.com
          • Dan Tebbs
            Woops, indeed I mispoke. Thanks Dave. -D ... -- Dan Tebbs Auric Consulting LLC Ph: 425-341-3261 Email: DanTebbs@gmail.com http://www.Linkedin.com/in/dantebbs
            Message 5 of 12 , Aug 16, 2012
              Woops, indeed I mispoke. Thanks Dave.

              -D

              On Wed, Aug 15, 2012 at 5:04 PM, Dave Hylands <dhylands@...> wrote:
               

              Hi,

              On Wed, Aug 15, 2012 at 4:55 PM, Dan Tebbs <dantebbs@...> wrote:


              Yes Tom,

              That does indeed mean the 'neutral' line. On U.S. power cords, that is the round one as opposed to the two blades.

              So there seems to be some confusing teminology.

              If you pull an electrical wire (Romex) from your wall and open it up, you'll find a black wire, a white wire, and a bare copper wire.

              In electrician's terms, the black wire is hot, the white wire is neutral, and the bare copper wire is ground.

              neutral and ground are connected together at your electrical panel.

              Here's a picture which identifies the corresponding positions on your typical US electrical outlet:
              http://www.homemaintenancereminder.com/articles_openground.htm.

              The frame ground on your power supply should be connected to the ground (round pin)

              --
              Dave Hylands
              Shuswap, BC, Canada
              http://www.davehylands.com




              --
              Dan Tebbs
              Auric Consulting LLC
              Ph: 425-341-3261
              Email: DanTebbs@...
              http://www.Linkedin.com/in/dantebbs
              http://www.AuricConsultingLLC.com

            • David Buckley
              Tom Not many people would describe the pins of an IEC plug - the type of connector on the back of your desktop PC and other equipment - as blades but rather
              Message 6 of 12 , Aug 16, 2012
                Tom
                Not many people would describe the pins of an IEC plug - the type of connector on the back of your desktop PC and other equipment - as 'blades' but rather as rectangular pins.
                'Blades' could lead people, who don't know as much about electricity as you do, to presume you are talking about plugs for wall outlets, with possible disastrous consequences.
                Terminology is everything.
                DAvid
                 
                 
                ----- Original Message -----
                Sent: Thursday, August 16, 2012 6:29 AM
                Subject: Re: [SeattleRobotics] "Safety Earth Connection"

                 

                Hi Tom,

                On Wed, Aug 15, 2012 at 9:51 PM, <twcarroll@...> wrote:


                Dave, DAvid and others,
                     No, I actually stated that the longer central blade is actually a 'blade' and not a longer round pin like in a typical plug.  The typical grounding 'pin' in a three conductor grounded male plug is a piece of rounded brass stock, formed into a 1/8" diameter pin that goes into the lower (or upper- depending how your female socket is oriented) central ground female 'hole.' 
                     What I am referring to is NOT a plug that you insert into a wall socket but the male three pin receptacle in the back of most newer electronic equipment.  It has three flat pine with the lower central flat pin the ground pin.  These are the receptacles that are basically a rounded rectangle shape with the two lower sides at 45 degree angles.  I know you realize what I am referring to.  Your flat screen TV, cable box, newer oscilloscope and so many items use this type of plug / receptacle for your removable power cord,- the other end of which has the three male pins,- two flat and a longer round brass ground pin.  It is this type of male receptacle that I am installing into the plastic box containing the power supply, fan and a terminal strip,- with red and black female banana connections on the outside for the different fixed voltages.  I have worked with all sorts of voltages all my life and know how to be safe and how to ground things.

                Ok - I know what you're talking about now.

                One off these: http://media.digikey.com/Photos/Qualtek%20Photos/703W-00%5E07.jpg (the old adage of a picture is worth a thousand words springs to mind).

                For some reason I was fixated on the part that plugs into the wall - Doh.

                --
                Dave Hylands
                Shuswap, BC, Canada
                http://www.davehylands.com

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