Can AC neutral and ground wire share the same bus?

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  • ChrisOlsonChrisOlson Banned Posts: 1,807 ✭✭
    Re: Can AC neutral and ground wire share the same bus?

    The thing is, I think if you buy the Power Distribution Panel for the XW (or the equivalent for the Outback system) that is already properly labeled or marked. Being I wanted to do it with the QO Load Centers the inspector looked it over and even made me take the covers off the boxes so he could see how it was wired inside. I had completely forgotten about the labeling requirement until he pointed it out - and the stickers came with the new box when I bought it.
    --
    Chris
  • ggunnggunn Solar Expert Posts: 1,973 ✭✭✭
    Re: Can AC neutral and ground wire share the same bus?
    Hairfarm wrote: »
    And that would be lethal, right, if the GFCI didn't trip?
    No. Since the plastic bucket is not grounded, the current path of the short would be entirely within the hair dryer and the conductors connected to it.
  • ggunnggunn Solar Expert Posts: 1,973 ✭✭✭
    Re: Can AC neutral and ground wire share the same bus?

    Quote Originally Posted by inetdog View Post
    What a lot of people do not realize is that a GFCI wired onto a two wire circuit will still give you the same protection ...
    NorthGuy wrote: »
    If the energy source is not grounded, there's no alternative route for the current. All current will always go through GFCI, so it'll never trip. In fact, if there's no ground, it's nothing that GFCI can protect you from.
    That is not correct. If a two pronged appliance has a current path to ground exterior to its conductors, the current in the neutral will be different from that in the hot, and the GFCI will trip. I have some Christmas lights in the trees in front of my house that are on two conductor wiring and on a GFCI outlet, and when it rains when they are on, the GFCI trips.
  • NorthGuyNorthGuy Solar Expert Posts: 1,913 ✭✭
    Re: Can AC neutral and ground wire share the same bus?
    ggunn wrote: »
    That is not correct. If a two pronged appliance has a current path to ground exterior to its conductors, the current in the neutral will be different from that in the hot, and the GFCI will trip. I have some Christmas lights in the trees in front of my house that are on two conductor wiring and on a GFCI outlet, and when it rains when they are on, the GFCI trips.

    In order for current to flow, you need a closed circuit.

    Normal circuit: Source - Hot wire - GFCI - Load - GFCI - Neutral wire - Source. GFCI does not trip because current is the same in and out

    Danger: Source - Hot wire - GFCI - you - Ground - Neutral wire - Source. GFCI trips because there's more current in than out.

    If Neutral is not connected to the Ground, you don't get zapped because the circuit is not completee:

    Source - Hot wire - GFCI - you - Ground --- broken here --- Neutral wire - Source. GFCI doesn't trip because current doesn't flow.

    As to your Christmas lights, the neutral is definitely connected to the ground (or at least must be by codes). If Neutral were left floating, GFCI wouldn't trip.
  • inetdoginetdog Solar Expert Posts: 3,123 ✭✭✭✭
    Re: Can AC neutral and ground wire share the same bus?
    ggunn wrote: »
    No. Since the plastic bucket is not grounded, the current path of the short would be entirely within the hair dryer and the conductors connected to it.

    But if you are in the bucket with the hair dryer, the voltage gradient in the water around the dryer may still be enough to harm you. I do not intend to perform that experiment. :-) And if instead of an isolated plastic bucket, you are in a fiberglass tub with a grounded metal drain pipe, the GFCI will blow and you will also be a likely part of the current path.
    SMA SB 3000, old BP panels.
  • PhotowhitPhotowhit Solar Expert Posts: 5,650 ✭✭✭✭✭
    Re: Can AC neutral and ground wire share the same bus?

    Might be a good time to put in the electrician 'trick' of working on things one handed or keeping a glove on the non primary hand and insulated shoes/boots, so if you are part of a curcuit, the current doesn't run across your heart...
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Magnum MS4024, Prosine 1800(now backup) and Exeltech 1100(former backup...lol), 660 ah 24v Forklift battery(now 10 years old). Off grid for 20 years (if I include 8 months on a bicycle).
    - Assorted other systems, pieces and to many panels in the closet to not do more projects.
  • ggunnggunn Solar Expert Posts: 1,973 ✭✭✭
    Re: Can AC neutral and ground wire share the same bus?
    NorthGuy wrote: »
    In order for current to flow, you need a closed circuit.

    Normal circuit: Source - Hot wire - GFCI - Load - GFCI - Neutral wire - Source. GFCI does not trip because current is the same in and out

    Danger: Source - Hot wire - GFCI - you - Ground - Neutral wire - Source. GFCI trips because there's more current in than out.

    If Neutral is not connected to the Ground, you don't get zapped because the circuit is not completee:

    Source - Hot wire - GFCI - you - Ground --- broken here --- Neutral wire - Source. GFCI doesn't trip because current doesn't flow.

    As to your Christmas lights, the neutral is definitely connected to the ground (or at least must be by codes). If Neutral were left floating, GFCI wouldn't trip.
    I understand pretty well how electricity works. Again, the post to which you replied:

    Quote Originally Posted by inetdog View Post
    What a lot of people do not realize is that a GFCI wired onto a two wire circuit will still give you the same protection


    A two wire circuit has the neutral tied to ground at the service. A leakage path to earth ground completes a circuit and the GFCI will trip.

    No one said anything about a floating neutral. If the neutral were floating, then the GFCI would not trip, but neither would it shock you if there were no other paths to ground. Of course, your home system would have other problems if it were 240V split phase.
  • ChrisOlsonChrisOlson Banned Posts: 1,807 ✭✭
    Re: Can AC neutral and ground wire share the same bus?
    ggunn wrote: »
    No one said anything about a floating neutral. If the neutral were floating, then the GFCI would not trip, but neither would it shock you if there were no other paths to ground. Of course, your home system would have other problems if it were 240V split phase.

    Floating neutral is common with small portable generators and mobile inverters for the reasons mentioned. However, it is not legal in a residence in the US or Canada.
    --
    Chris
  • NorthGuyNorthGuy Solar Expert Posts: 1,913 ✭✭
    Re: Can AC neutral and ground wire share the same bus?
    ggunn wrote: »
    No one said anything about a floating neutral. If the neutral were floating, then the GFCI would not trip, but neither would it shock you if there were no other paths to ground.

    I did say about floating neutral. That's what I said:
    NorthGuy wrote: »
    If the energy source is not grounded, there's no alternative route for the current. All current will always go through GFCI, so it'll never trip. In fact, if there's no ground, it's nothing that GFCI can protect you from.

    In my mind, it has exactly the same meaning as your sentence above.

    For some reason, you quoted my words and said: :confused:
    ggunn wrote: »
    That is not correct ...

    So, I just tried to explain in more details ...
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Can AC neutral and ground wire share the same bus?

    I think this dead horse has been flayed sufficiently.
  • ggunnggunn Solar Expert Posts: 1,973 ✭✭✭
    Re: Can AC neutral and ground wire share the same bus?
    I think this dead horse has been flayed sufficiently.
    Aw c'mon! Doncha wanna flog it some more? I can still make out a couple of hooves! :D
  • inetdoginetdog Solar Expert Posts: 3,123 ✭✭✭✭
    Re: Can AC neutral and ground wire share the same bus?
    I think this dead horse has been flayed sufficiently.
    You can lead a horse to water, but then he might get electrocuted.
    SMA SB 3000, old BP panels.
  • nielniel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: Can AC neutral and ground wire share the same bus?

    only if he is wearing metal horseshoes.:roll:
  • westbranchwestbranch Solar Expert Posts: 5,183 ✭✭✭✭
    Re: Can AC neutral and ground wire share the same bus?

    when at the water trough there is usually water on the ground, making a good bit of mud... great ground...
     
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