Second grounding electrode

[clavila]

Hi

On a 240/120V 3-wire service, If I have my service drop, meter, ground electrode and main breaker, main bonding jumper at the edge of the property, and I have a 4-wire underground feeder to the main panel of the house that is located 90 feet away, do I need another ground electrode on this main panel (only panel really) at the panel's location inside the house? Or is my grounding conductor enough system grounding for this service. Assuming a 150amp panel.

If I have the same situation but instead of an underground feeder, I use a triplex-cable, do I need the second ground electrode installed at the panels location inside the house? Am I allowed to do this or do I need to take a quadruplex cable?

Is this considered a Separately derived system?

Best regards and thanks,

Carlos Avila

 

[jumper]

I would look at 250.32.

 

[texie]

Hi

On a 240/120V 3-wire service, If I have my service drop, meter, ground electrode and main breaker, main bonding jumper at the edge of the property, and I have a 4-wire underground feeder to the main panel of the house that is located 90 feet away, do I need another ground electrode on this main panel (only panel really) at the panel's location inside the house? Or is my grounding conductor enough system grounding for this service. Assuming a 150amp panel.

If I have the same situation but instead of an underground feeder, I use a triplex-cable, do I need the second ground electrode installed at the panels location inside the house? Am I allowed to do this or do I need to take a quadruplex cable?

Is this considered a Separately derived system?

Best regards and thanks,

Carlos Avila

Yep 250.32.
Overhead or underground you need an EGC run with the feeder (this is a feeder). That would mean quadplex if going overhead. And yes, you must have a GES at the building connected to the EGC at the building disconnect (not the neutral).

 

[clavila]

Yep 250.32.
Overhead or underground you need an EGC run with the feeder (this is a feeder). That would mean quadplex if going overhead. And yes, you must have a GES at the building connected to the EGC at the building disconnect (not the neutral).

What about this exception in 250.32 A
"Exception: A grounding electrode shall not be required where only a single branch circuit, including a multiwire branch circuit, supplies the building or structure and the branch circuit includes an equipment grounding conductor
for grounding the normally non?current-carrying metal parts of equipment."

Is this talking a about a second GES at the panelboard?.

The building disconnect is at the service drop, not at the building or at the panelboard. This part confuses me sorry.

Thanks,

Carlos

 

[GoldDigger]

What about this exception in 250.32 A
"Exception: A grounding electrode shall not be required where only a single branch circuit, including a multiwire branch circuit, supplies the building or structure and the branch circuit includes an equipment grounding conductor
for grounding the normally non?current-carrying metal parts of equipment."

Is this talking a about a second GES at the panelboard?.

The building disconnect is at the service drop, not at the building or at the panelboard. This part confuses me sorry.

Thanks,

Carlos

The NEC makes a clear distinction between a branch circuit and a feeder circuit, (although some unusual circuits may be both.)
Under the definition of branch circuit, it does not apply whenever there is a downstream OCPD between the circuit and the loads. So the single circuit going to the house main panel is definitely a feeder circuit and not a branch circuit.
Think instead of a garage or shed where there is only one combined lighting and receptacle circuit, or two 120V circuits back to back on one MWBC.

 

[clavila]

The NEC makes a clear distinction between a branch circuit and a feeder circuit, (although some unusual circuits may be both.)
Under the definition of branch circuit, it does not apply whenever there is a downstream OCPD between the circuit and the loads. So the single circuit going to the house main panel is definitely a feeder circuit and not a branch circuit.
Think instead of a garage or shed where there is only one combined lighting and receptacle circuit, or two 120V circuits back to back on one MWBC.

Ok. This would be a single circuit to a building or structure. Got it.

In case of the feeder, do I need two GES one at the main breaker (METER COLUMN) and a second GES at the house close to the main panelboard.???
If so, is there a minimum distance where this is required or does it not depend on the distance, just any separation.

What NEC specific article requires this?

thanks again.

 

[GoldDigger]

It just depends on there being separate structures to which the different panels are attached. Two buildings without a common slab or roof would be two structures even if they were only 6" apart.

 

[jumper]

And yes each structure needs a GES unless you meet one of the exceptions.

 

[clavila]

It just depends on there being separate structures to which the different panels are attached. Two buildings without a common slab or roof would be two structures even if they were only 6" apart.

In my case it's just the meter column with the meter, the main breaker and the GES on one side and the house on the other.

 

[GoldDigger]

In my case it's just the meter column with the meter, the main breaker and the GES on one side and the house on the other.

There needs to be a GES at the meter column because it is the location of the service disconnect. But even if that were not the case, the meter column would still be a structure, in the opinion of the majority of those commenting.
If the meter etc. were attached to the utility pole, that might not be a structure subject to the NEC though.

 

[clavila]

There needs to be a GES at the meter column because it is the location of the service disconnect. But even if that were not the case, the meter column would still be a structure, in the opinion of the majority of those commenting.
If the meter etc. were attached to the utility pole, that might not be a structure subject to the NEC though.

Im OK with that, but I'm not fully ok with the a second electrode (ground rod) at the panelboard. Is this intended more to the need to connect metal piping or other metal structures that may be used as grounding according to NEC 250.52 to the GES at the meter column? What if I don't have those metal structures?

Thanks,

Carlos

 

[edlee]

Im OK with that, but I'm not fully ok with the a second electrode (ground rod) at the panelboard. Is this intended more to the need to connect metal piping or other metal structures that may be used as grounding according to NEC 250.52 to the GES at the meter column? What if I don't have those metal structures?

Thanks,

Carlos

The building needs its own grounding system. Suppose it was hit by lightning and the only system grounding point was 90 feet away?

 

[ggunn]

Doesn't the second ground rod need to be bonded to the first via a conductor in addition to the EGC connecting the two panels and external to the conduit containing the feeder?

 

[kwired]

There needs to be a GES at the meter column because it is the location of the service disconnect. But even if that were not the case, the meter column would still be a structure, in the opinion of the majority of those commenting.
If the meter etc. were attached to the utility pole, that might not be a structure subject to the NEC though.

If attached to a utility pole it may or may not be considered the service disconnect, really depends on where the "service point" is.

Im OK with that, but I'm not fully ok with the a second electrode (ground rod) at the panelboard. Is this intended more to the need to connect metal piping or other metal structures that may be used as grounding according to NEC 250.52 to the GES at the meter column? What if I don't have those metal structures?
Thanks,

Carlos

If you don't have qualifying structural steel, qualifying water pipe or qualifying CEE (generally only for new construction), then you must use a "made elecrode" such as rod or pipe electrodes or a ground ring. Each structure needs it's own grounding electrode system. NEC defines structure but doesn't really define separate structure and this is subjected to interpretation and will vary in some places. Most places though your remote service disconnecting means will be considered a separate structure and will require a GES at the meter as well as at each additional structure fed from it.

 

[GoldDigger]

If attached to a utility pole it may or may not be considered the service disconnect, really depends on where the "service point" is.

I was addressing specifically the OP's situation, and did not mean to generalize to any meter location. Thanks for pointing out that the service point is a matter of specification and cannot necessarily be recognized in the field without more information.

If I have my service drop, meter, ground electrode and main breaker, main bonding jumper at the edge of the property,

So there is an electrode there for sure.

 

[kwired]

I was addressing specifically the OP's situation, and did not mean to generalize to any meter location. Thanks for pointing out that the service point is a matter of specification and cannot necessarily be recognized in the field without more information.

So there is an electrode there for sure.

Correct in that there still will be a grounding electrode system at each structure, I guess what I really was getting at is if the meter/disconnect is not on the load side of the service point then it is not the service disconnect, and if that is the case the lines to the house are service conductors instead of feeder conductors.