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Using one phase, of the supply, and and the "ground" to form a circuit

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    Using one phase, of the supply, and and the "ground" to form a circuit

    Hello,

    Is it safe to just use "one" phase of the supply and connect it to a load and directly to the "ground" to
    form the ckt/loop??

    pls refer to the attachment.

    Thanks in advance,
    Newbie here
    Attached Files

    #2
    Usually no, not safe. There are a few instances where it could be considered safe, but still not legal.

    Comment


      #3
      If you wanted to get pedantic about it, that's how all single pole circuit breakers in the main panel are wired.

      Comment


        #4
        Originally posted by jaylectricity View Post
        If you wanted to get pedantic about it, that's how all single pole circuit breakers in the main panel are wired.
        No, that involves a connection to the grounded conductor (neutral in this case), not to ground/EGC.

        Comment


          #5
          Just a passing observation from the ignorant Brit.......
          I have noticed that there is a tenancy to equate neutral with ground.
          I know that they are not the same. As I said, just an observation...........
          Si hoc legere scis nimium eruditionis habes.

          Comment


            #6
            Originally posted by jaylectricity View Post
            Usually no, not safe. There are a few instances where it could be considered safe, but still not legal.
            What are those instances that can be considered "it is safe"? Will it make it safe if you'll cover everything with non-conductive materials

            Comment


              #7
              Single-wire high-voltage distribution in Canadian "out-back" uses the ground (as in dirt) as the return path for the HV primary of the distribution transformers.

              Comment


                #8
                Safety is always a relative term.

                My understanding is that there were wartime (WWII) system where power was distributed using a _single_ 'hot' conductor with the conduit as the 'return' wire. These _worked_ but if the conduit system were to be damaged then the conduit itself would become energized! As long as the conduit was intact, IMHO it was a distant cousin to 'safe'.

                For wiring certain large appliances, it used to be permitted to install systems where the neutral was used as the 'equipment ground' for the frame of the appliance. Existing installations for ovens and clothes dryers may still used the shared neutral and ground.

                Neutral and ground are usually combined in the service drop supplying a home.

                In general, you want to have two separate conductors at approximately 0V relative to earth: your 'grounded' conductor which is supposed to carry current, and your 'equipment grounding and bonding conductor' which is for connecting all metal that _isn't_ supposed to carry current, to guarantee that this metal remains at 0V.

                The problem with sharing 'grounded circuit conductor' and 'grounding or bonding conductor' is that if the ground opens you will now energize all of the metal connected to the grounding or bonding conductor.

                -Jon

                Comment


                  #9
                  Originally posted by proxygio View Post
                  What are those instances that can be considered "it is safe"? Will it make it safe if you'll cover everything with non-conductive materials
                  If the ground is an insulated conductor and it was connected to the neutral bar in a main panel and nothing else. Which in effect makes it the neutral. But like I said...pedantry.

                  Comment


                    #10
                    Originally posted by proxygio View Post
                    Hello,

                    Is it safe to just use "one" phase of the supply and connect it to a load and directly to the "ground" to
                    form the ckt/loop??

                    pls refer to the attachment.

                    Thanks in advance,
                    Newbie here
                    Theoretically the same as "Neutral" in a grounded neutral system? Yes.

                    "Safe"? Define what that means. In the NEC world, the REASON why you are not permitted to use the Electrical Grounding Conductor AS the "neutral", even though they are theoretically at the same potential, is because it is in fact NOT considered to be "safe", and the NEC is all about safety. So is it "safe" as defined here? No.

                    "Legal", definitely NO! Because... IT IS NOT CONSIDERED SAFE!

                    Done all the time by DIYers and hacks? Yes, unfortunately. In fact that's one way to tell when something has been wired by a DIYer or a hack.

                    Done sometimes by power utilities, referred to as a "SWER" (Single Wire Earth Return) system ? Yes, but remember, utilities are NOT required to follow the NEC, they have their own rules, and maintain their own equipment. So the safety risks involved involved in a SWER system are born by THEM, not us.
                    __________________________________________________ ____________________________
                    Many people are shocked when they discover I am not a good electrician...

                    I'm in California, ergo I am still stuck on the 2014 NEC... We'll get around to the 2017 code in around 2021.

                    Comment


                      #11
                      Originally posted by proxygio View Post
                      Hello,

                      Is it safe to just use "one" phase of the supply and connect it to a load and directly to the "ground" to
                      form the ckt/loop??

                      pls refer to the attachment.

                      Thanks in advance,
                      Newbie here
                      No. Not safe. The ground is bonded to other metal stuff throughout the load site. The neutral is isolated from all that metal stuff (no neutral-ground bonds beyond the main disconnect).

                      By using the ground to carry load current, you have parallel current paths through metal stuff and can have load current running through structures, equipment, and other metal stuff at the site.

                      Don't do it.
                      BB+/BB=?

                      Comment


                        #12
                        Originally posted by Jraef View Post
                        Theoretically the same as "Neutral" in a grounded neutral system? Yes.
                        Not beyond the bonding jumper.
                        BB+/BB=?

                        Comment


                          #13
                          Originally posted by proxygio View Post
                          Hello,

                          Is it safe to just use "one" phase of the supply and connect it to a load and directly to the "ground" to
                          form the ckt/loop??

                          pls refer to the attachment.

                          Thanks in advance,
                          Newbie here

                          No, it is not safe.

                          There is a difference between neutral and ground. Neutral has the same voltage as ground, however neutral is intended to carry current under ordinary circumstances, and ground is not.

                          Neutral is ultimately bonded to ground, but this is only permitted to occur at exclusively one point on a service. Usually at the main service disconnect.


                          Neutral carries return current of ordinary operation.
                          Ground only carries fault current, in the undesired event that a live wire faults to a metal structure. Ground is bonded to all metal that doesn't intentionally carry current, in order to provide a return path and clear the protection device (eg breaker).

                          Comment


                            #14
                            Originally posted by Jraef View Post
                            ...
                            "Legal", definitely NO! ...
                            Without getting down to the conductor identification rules in 200.7 and 250.119 what code rule really says we can't do that?
                            Don, Illinois
                            (All code citations are 2017 unless otherwise noted)

                            Comment


                              #15
                              Originally posted by don_resqcapt19 View Post
                              Without getting down to the conductor identification rules in 200.7 and 250.119 what code rule really says we can't do that?
                              Huh, you know what? You may have identified another of my internal "myths". It was my gut reaction, but when I think about it, why is that different from what the circuit would look like on a corner grounded delta 3 phase system feeding a single phase load? You are right in that identification would be crucial, but not illegal to do it? I'm now questioning my long held belief that you can't use the ground connection as a current carrying conductor. It was the way I was taught as an apprentice doing residential work, but when I got into industrial work, I guess I never made the leap of logic to recognize the inconsistency.
                              __________________________________________________ ____________________________
                              Many people are shocked when they discover I am not a good electrician...

                              I'm in California, ergo I am still stuck on the 2014 NEC... We'll get around to the 2017 code in around 2021.

                              Comment

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