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    Grounding vs. Grounded

    Grounding vs. Grounded

    New postby jbeech on Sun Jun 21, 2015 10:47 am

    Jerry,

    Transformer on the pole feeds my house and the barn. Each has its own meter.

    1. Regarding the panel on the side of the house - the one with the meter and the disconnect mounted within - is this the service-panel?

    2. Regarding the panel inside the house - the one, which is full of breakers for all the various circuits - is this called the load-panel? And is this called a sub-panel of the service-panel, or is it understood and sub-panels of the load-panel are the ones called a sub-panel?

    3. Some further questions;

    a. Is the service panel the 'only' place where the G-bar (grounding-bar) physically join the grounded-bar (neutral)?

    b. Is the grounded-bar supposed to be electrically isolated from the metal box of all panels except the service-panel itself? I wonder because my house (built in 1982) when I take a meter to the load-panel in the garage (the one in the garage which is full of breakers) I get continuity between grounded-bar (white-neutral) and the grounding bar (all the green/bare wires).

    4. So I wonder, is this continuity OK?

    a. Or should this panel have an isolated neutral-bar, e.g. not electrical continuous with the metal panel or the grounding bar?

    b. Does this mean the green/bare wires go to ground but white wires don't because the grounded-bar is supposed to be isolated from the metal case of the load-panel? Sorry if I sound confused but the fact is I am!

    5. As with the service-panel at the house, my detached barn's service-panel (with its own meter), has a grounding-rod driven into the ground nearby. From there underground wire goes to the load-panel inside. My plan is to run a 20hp RPC (rotary phase converter) off a 100A breaker within the load-panel. Next, I want to run the 3-phase output of the RPC to a separate 3-phase panel (and take Black, Red, Blue, White plus Green to power several 3-phase machines - each through their own breakers in the 3-phase sub-panel).

    a. Does the 3-phase sub-panel require a separate grounding rod?

    b. Also, do I need disconnects at the individual machines, or is just having the breaker be the disconnect, OK?

    Lots of questions we could probably nail down in two minutes of conversation.
    --
    John Beech
    jbeech
     
    Posts: 2
    Joined: Sat Jun 20, 2015 12:42 pm

    Re: Grounding vs. Grounded

    New postby Jerry Peck - Codeman on Sun Jun 21, 2015 2:59 pm

    John,

    jbeech wrote:Transformer on the pole feeds my house and the barn. Each has its own meter.


    That likely means that each has its own service, its own service equipment, its own service disconnect, and its own grounding electrode system - to clarify this ... the barn is no fed from the house panel with the having its own meter, the barn has a separate service directly from the transformer, right (this is what I am basing my answers on ... each having its own service).

    1. Regarding the panel on the side of the house - the one with the meter and the disconnect mounted within - is this the service-panel?


    Yes. That is the service equipment panel (or simply the 'service equipment') for the house, the barn would then have its own service equipment and service disconnect.

    2. Regarding the panel inside the house - the one, which is full of breakers for all the various circuits - is this called the load-panel? And is this called a sub-panel of the service-panel, or is it understood and sub-panels of the load-panel are the ones called a sub-panel?


    Lose the term "sub-panel" and it gets a lot easier to follow, besides, the code addresses two types of panels: a) panels; b) panels used as service equipment. There are not "sub-panels" in the code and many people get confused when they add in that term - there are "panels" and "panels used as service equipment" ("service equipment" or "service equipment panel" for simplicity).

    3. Some further questions;
    a. Is the service panel the 'only' place where the G-bar (grounding-bar) physically join the grounded-bar (neutral)?


    The service equipment panel is the only place the neutral is bonded to ground, and that is done on the load side of the service disconnect (which, for practical purposes, means the neutral is bonded to ground is done inside the service panel where the panel is designed for it to be done).

    3. b. Is the grounded-bar supposed to be electrically isolated from the metal box of all panels except the service-panel itself? I wonder because my house (built in 1982) when I take a meter to the load-panel in the garage (the one in the garage which is full of breakers) I get continuity between grounded-bar (white-neutral) and the grounding bar (all the green/bare wires).


    I suspect you are referring to the terminal bar where the grounded conductors are terminated, so, yes, that grounded (neutral) conductor terminal bar is to be isolated from ground at all locations downstream of the service equipment (it is bonded to ground in the service equipment, no where else).

    See 4. a. for the rest of the answer.

    4. So I wonder, is this continuity OK?
    a. Or should this panel have an isolated neutral-bar, e.g. not electrical continuous with the metal panel or the grounding bar?


    Define "continuity".

    Yes, you will get a reading between neutral and ground anywhere along the system be, back at the service equipment, the two conductors are bonded (connected) together. There will be varying amounts of resistance depending on wire sizes and wire lengths, but if you are simply testing whether or not there is a connection between the two, there is. Here is an example: let's say you are measuring at a receptacle 100 feet from the service equipment - there will be 100 feet or neutral (grounded) conductor from where you are measuring, the connection of the two in the panel, and 100 feet of grounding conductor back to where you are measuring.

    4. b. Does this mean the green/bare wires go to ground but white wires don't because the grounded-bar is supposed to be isolated from the metal case of the load-panel? Sorry if I sound confused but the fact is I am!


    Yes, the green and bare groundING wires to a terminal bar which is connected to the metal enclosure.

    Yes, the white neutral groundED wires do not terminate there because they are required to be isolated from ground ... at that point (which is downstream of the service equipment where they are bonded together).

    Let's make sure the above are clarified before continuing.
    Jerry Peck - CodeMan
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    Re: Grounding vs. Grounded

    New postby jbeech on Sun Jun 21, 2015 8:04 pm

    Jerry Peck - Codeman wrote:John,

    jbeech wrote:Transformer on the pole feeds my house and the barn. Each has its own meter.


    That likely means that each has its own service, its own service equipment, its own service disconnect, and its own grounding electrode system - to clarify this ... the barn is no fed from the house panel with the having its own meter, the barn has a separate service directly from the transformer, right (this is what I am basing my answers on ... each having its own service).


    Yes, each has its own service equipment with disconnect.

    Yes, the green and bare groundING wires to a terminal bar which is connected to the metal enclosure.

    Yes, the white neutral groundED wires do not terminate there because they are required to be isolated from ground ... at that point (which is downstream of the service equipment where they are bonded together).

    Let's make sure the above are clarified before continuing.


    Now I wonder, how do I differentiate between the terminal bar for the grounded-bar vs. the grounding-bar within the panel (the one with all the breakers) - and how do I know which is which when it's all assembled? Is there some mark, or . . .?

    Finally, what do we call it when another panel is wired off the panel, what "m referring to as a sub-panel - this, versus a panel coming straight from the service equipment? I mean, is there a name to differentiate this panel or is it still just a panel?
    jbeech
     
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    Re: Grounding vs. Grounded

    New postby Jerry Peck - Codeman on Sun Jun 21, 2015 8:59 pm

    jbeech wrote:Now I wonder, how do I differentiate between the terminal bar for the grounded-bar vs. the grounding-bar within the panel (the one with all the breakers) - and how do I know which is which when it's all assembled? Is there some mark, or . . .?


    Yes, the correct terminal bar is shown on the diagram printed on the label. The terminal bar with the neutral terminal lug will be the terminal bar for the neutral conductors, and, some panels will have the terminal bars interconnected such that either can serve as the neutral terminal bar - but the options will be shown on the diagram.

    Finally, what do we call it when another panel is wired off the panel, what "m referring to as a sub-panel - this, versus a panel coming straight from the service equipment? I mean, is there a name to differentiate this panel or is it still just a panel?


    There is the service equipment panel which has the service disconnect in it.

    Then there are simply panels. One could call them 'remote' panels as they are 'remote' from the service equipment panel, or load centers, or various other descriptive wording in front of "panel", or, just "electrical panel". If there are more than one electrical panels, I would describe them as electrical panel in (give location), with the next one being electrical panel in (give its location), and if there are more than one in one location, I might refer to them as the 'left panel', the 'center panel', the 'right panel', etc. then make a recommendation that the panels be labeled as 'Panel A', 'Panel B', 'Panel C', etc.

    Throwing in terms such as 'sub panel' or 'main panel' are meaningless - while an electrician may refer to the service equipment panel as the "main panel", the occupants may look at the service equipment with its one breaker and the other panel with 30 breakers and (logically) think of the panel with 30 breakers as the "main panel" because, to them, it is the "main panel" they will be concerned with as it has breakers for everything.

    I don't know if you have seen the old pull out fuse panels with the two pull out "mains", one for the water heater, and one for the rest of the panel? My guess is that is where the term "main panel" came from as that panel had the "mains" in it. In reality, though, that was the "service equipment panel" and those two "mains" were the two "main service disconnects".

    Likewise, I suspect that the term "sub panel" came from a panel which was sub-fed from another panel, and that panel could sub-feed yet another panel, and that panel could also sub-feed another panel ... would you call them 'sub panel', 'sub sub panel' and 'sub sub sub panel'? Likely not. Besides, they are all wired the same and they are all simply "panels".
    Jerry Peck - CodeMan
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