GROUND NEUTRAL BOND at First Point of Service, but what about at Power Source???

[WattAboutThat]

When considering Neutral Ground Bonding

in a Completely OFF GRID system…

If instead of a an electric company grid transformer supplying electricity
as the source of power,
we now consider a
completely OFF GRID solar outbuilding,
as the originating source of power
(some distance from service structure
where a main service panel
will be the Main Panel).

1) Do we treat the outbuilding
as if it were the essentially a grid supply?

2) Do we create a neutral ground bond
in the outbuilding,
as if it were the pole transformer,
since the source of power
is generated there?

3) Do we create a neutral ground bond
at the Main Service Panel,
located in the service structure,
not near the power generating
out building?

4) if there is a NG bond
at the power producing outbuilding,
and a NG bond
at the Main Service Panel
in the service building,
if a short circuit or ground fault occurs,

a) WILL IT TRIP THE BREAKER
in the Main Service Panel
located in the service building?

b) will it trip the breaker
in the power outbuilding
that feeds
the main service panel
in the service building?

c) should each building
have their own ground rods?

5) In the power producing outbuilding
can the DC side and the AC side,
use the same Ground rod?
or will this create an issue?

This is a tough one to figure out,
I need all points of view and considerations.

Because I dont want anyone to get hurt,
and want maximum safety accounted for
in the design and install.

I have watched tons of videos
by electricians, but nothing explains
what to do,
if you are the electric company side,
and supplier of the power source, and
you are also the customer side,
and serviced building.

Thank you

 

[timselectric]

First question:
You say "completely off grid".
But you are saying that the "main service panel" in in another structure.
Is there actually grid available or not?

 

[WattAboutThat]

Grid is not available.

I am using a small gas generator for temporary power until i get the big system installed.

 

[WattAboutThat]

Main Service Panel - would be the same type panel as if you were getting power from the grid, but instead it will be getting power from the inverters (2x18kPV), which will be located in a small shed to isolate it from the main structure.

 

[timselectric]

Main Service Panel - would be the same type panel as if you were getting power from the grid, but instead it will be getting power from the inverters (2x18kPV), which will be located in a small shed to isolate it from the main structure.

First distribution panel from the inverters (in the shed) is the main service panel. Everything after that is a sub panel. N/G bond should be in the main service panel. Ground and neutral remain separate after that.
Ground rod near and connected to the main service panel.
Some jurisdictions require a ground rod at each building. If not required (or no inspection) I would not recommend them.
Either way, both a neutral and ground conductor are ran everywhere.

 

[WattAboutThat]

First distribution panel from the inverters (in the shed) is the main service panel. Everything after that is a sub panel. N/G bond should be in the main service panel. Ground and neutral remain separate after that.
Ground rod near and connected to the main service panel.
Some jurisdictions require a ground rod at each building. If not required (or no inspection) I would not recommend them.
Either way, both a neutral and ground conductor are ran everywhere.

Thanks!

 

[Zwy]

When considering Neutral Ground Bonding

in a Completely OFF GRID system…

Completely off grid= source

All current returns to source, whether thru you or wires.

If instead of a an electric company grid transformer supplying electricity
as the source of power,
we now consider a
completely OFF GRID solar outbuilding,
as the originating source of power
(some distance from service structure
where a main service panel
will be the Main Panel).

First disconnect at the inverters is the main service panel and needs to be either bonded in the inverter or at that main service panel.

You need to determine if the inverter bonds N-G or not. I see in another reply, you mention a generator. This does complicate things if you do intend to use the generator as backup- you need to determine if the generator is bonded and whether you intend to use bypass in an inverter or a transfer switch.

1) Do we treat the outbuilding
as if it were the essentially a grid supply?

If inverters are in that building and it is completely off grid, then it is source, the same as a grid transformer.

2) Do we create a neutral ground bond
in the outbuilding,
as if it were the pole transformer,
since the source of power
is generated there?

Answered above.

3) Do we create a neutral ground bond
at the Main Service Panel,
located in the service structure,
not near the power generating
out building?

No.

4) if there is a NG bond
at the power producing outbuilding,
and a NG bond
at the Main Service Panel
in the service building,
if a short circuit or ground fault occurs,

Do not have 2 N-G bonds on the system.

a) WILL IT TRIP THE BREAKER
in the Main Service Panel
located in the service building?

b) will it trip the breaker
in the power outbuilding
that feeds
the main service panel
in the service building?

c) should each building
have their own ground rods?

5) In the power producing outbuilding
can the DC side and the AC side,
use the same Ground rod?
or will this create an issue?

I have ground from array to the ground rod at the house and the AC panels also use this ground rod. My battery cabinet also has an EGC to the ground rod but the DC negative is not tied to the ground system.

NEC requires a ground rod at each structure. It also requires a ground conductor from the main service panel that is N-G bonded to each structure tied to the ground rod at that structure. This is to provide a low impedance path back to source.

This is a tough one to figure out,
I need all points of view and considerations.

Because I dont want anyone to get hurt,
and want maximum safety accounted for
in the design and install.

I have watched tons of videos
by electricians, but nothing explains
what to do,
if you are the electric company side,
and supplier of the power source, and
you are also the customer side,
and serviced building.

Thank you

 

[WattAboutThat]

Completely off grid= source

All current returns to source, whether thru you or wires.



First disconnect at the inverters is the main service panel and needs to be either bonded in the inverter or at that main service panel.

You need to determine if the inverter bonds N-G or not. I see in another reply, you mention a generator. This does complicate things if you do intend to use the generator as backup- you need to determine if the generator is bonded and whether you intend to use bypass in an inverter or a transfer switch.



If inverters are in that building and it is completely off grid, then it is source, the same as a grid transformer.



Answered above.



No.


Do not have 2 N-G bonds on the system.




I have ground from array to the ground rod at the house and the AC panels also use this ground rod. My battery cabinet also has an EGC to the ground rod but the DC negative is not tied to the ground system.

NEC requires a ground rod at each structure. It also requires a ground conductor from the main service panel that is N-G bonded to each structure tied to the ground rod at that structure. This is to provide a low impedance path back to source.

This has been very informative,
and much appreciated.

Thank you for taking the time
to help me understand this.