Grounding electrode conductor question

[danno1202]

[ONFIG]12534[/ATTACH]

I am in the process of installing this service. One panel is for normal power and one is for off peak. The panels will have separate runs to the remote meters. My question is, do I need two separate grounding electrodes, or just one? There is also an exposed re bar from the foundation nearby that the builder might have intended to be a ground connection point. I am planning on connecting the meter enclosures via the grounded neutral conductor, no separate ground seems to be necessary between the meters and the panels.

 

[J.P.]

All coming out of the same transformer? One grounding system. Bond all of the cans.

You don't know what that rebar really is.
Install your own grounding electrode or find out for sure that there is 18ft of rebar in the concrete and that is the end of it.

You can tie to it if you want, but drive your own grounding electrodes as well.

 

[augie47]

From the pictures, it appears your meters are actually meter/breaker combos. If so in most jurisdictions, 250.32 would apply and you would need an equipment grounding conductor from the meter/breaker pedestal to the residence panels.
In either event, a grounding electrode system at the building must be established and both disconnecting means should be connected to the one electrode system.
If you can confirm the the exposed rebar is attached to the the ufer ground, that is the only electrode required at the building.
Locally we would have to drive ground rod(s) at the meters per NEC if there are overcurrent devices there and per POCO rules if it is only a meter.

 

[danno1202]

From the pictures, it appears your meters are actually meter/breaker combos. If so in most jurisdictions, 250.32 would apply and you would need an equipment grounding conductor from the meter/breaker pedestal to the residence panels.
In either event, a grounding electrode system at the building must be established and both disconnecting means should be connected to the one electrode system.
If you can confirm the the exposed rebar is attached to the the ufer ground, that is the only electrode required at the building.
Locally we would have to drive ground rod(s) at the meters per NEC if there are overcurrent devices there and per POCO rules if it is only a meter.

Thanks Augie47. Yes, they are meter/breaker combos. However the terminal for the grounded conductor is connected directly to the meter enclosure. (Not isolated) Wouldn't an EGC essentially duplicate that connection, as the grounded conductor will be bonded to ground at the other end (the service disconnects)

 

[danno1202]

here's what one looks like inside

here's what one looks like inside

From the pictures, it appears your meters are actually meter/breaker combos. If so in most jurisdictions, 250.32 would apply and you would need an equipment grounding conductor from the meter/breaker pedestal to the residence panels.
In either event, a grounding electrode system at the building must be established and both disconnecting means should be connected to the one electrode system.
If you can confirm the the exposed rebar is attached to the the ufer ground, that is the only electrode required at the building.
Locally we would have to drive ground rod(s) at the meters per NEC if there are overcurrent devices there and per POCO rules if it is only a meter.

 

[J.P.]

The meter bases have breakers in them that supply the panels inside?

If so the meter bases are your service disconnects. Ground and bond there.

carry whatever size your service calls for bonding wire to the panels.

 

[augie47]

Thanks Augie47. Yes, they are meter/breaker combos. However the terminal for the grounded conductor is connected directly to the meter enclosure. (Not isolated) Wouldn't an EGC essentially duplicate that connection, as the grounded conductor will be bonded to ground at the other end (the service disconnects)

The grounded conductor (neutral) should not be bonded at the panel (buliLding) end. See 250.32 & 250.24(A)(5).
With you service disconnects at the meter pedestal, an EGC is brought to the house panels and connected to the grounding electrode system at the house.
See 250.32, 250.24(A)(5) and 225 Part II

 

[Dennis Alwon]

Is it compliant to have 2 feeders feed the same building. I don't think so --- 225.30

 

[augie47]

Is it compliant to have 2 feeders feed the same building. I don't think so --- 225.30

I have not checked the latest Codes to see if there was any wording since '08 but I'd say your read is 100%. However, seeing that 230.2(D) would allow two services (assuming this situation meets "two rate schedules") , I would not be surprised to see this accepted by his AHJ since it accommodates POCO.

 

[Dennis Alwon]

I am guessing that 225.30(D) may be an out-- "for different uses"

(D) Different Characteristics. Additional feeders or
branch circuits shall be permitted for different voltages,
frequencies, or phases or for different uses, such as control
of outside lighting from multiple locations

 

[augie47]

I am guessing that 225.30(D) may be an out-- "for different uses"

In see it being allowed, but, like you, it requires an "out"

 

[danno1202]

Should there be just the one ground rod at the service disconnects (meter pedestals), or a ground rod there and at the house also? Looks like I need to run a #4 EGC from the meter enclosures to the house. And is the supposed to be just one EGC from the meters to the house in one of the conduits, or one in each conduit? The grounded conductor will be bonded at the meter enclosures, not the house. Thanks.

The grounded conductor (neutral) should not be bonded at the panel (buliLding) end. See 250.32 & 250.24(A)(5).
With you service disconnects at the meter pedestal, an EGC is brought to the house panels and connected to the grounding electrode system at the house.
See 250.32, 250.24(A)(5) and 225 Part II

 

[danno1202]

Here's a diagram of what I an doing. Not exactly sure how to bond all of this together yet.