Bonding Grounds and Neutrals

[ccrump]

The scenario I have been given is a 200 amp meter base that goes to a 200 amp main breaker panel. The neutral and grounds are bonded in the main breaker panel due to the being the first point of disconnect, since this panel will feed three subpanels. The meter base has a 6 awg that connects the grounding bus bar to the neutral/ground lug in the meter base. The grounding bus bar in the main panel goes to a 5/8 grounding rod at the bottom of the pole. The meter base also has a 5/8 grounding rod that has a seperate 6-awg bonding from it. Therefore, the meter base has a 6 awg that goes to the main breaker panel that has its own grounding rod, and the meter base also has another ground rod attached to it. However, the ground rods are not connected at the ground. Does this scenario seem up to code, and if not, why? Thank you for the help. This scenario is in an educational debate within my state and has been studied extensively with no concrete answers.

 

[infinity]

Grounding electrodes can be connected at any point in the system from the service point to the service disconnect. What you have is just that.

Welcome to the forum.

 

[ccrump]

Grounding electrodes can be connected at any point in the system from the service point to the service disconnect. What you have is just that.

Welcome to the forum.

Thank you for the reply! But it is acceptable to have two separate grounds rods that will be driven beside each other that do not have a direct connection? I thought they may have two separate potentials.

 

[wwhitney]

The meter base has a 6 awg that connects the grounding bus bar to the neutral/ground lug in the meter base.

If by "grounding bus bar" you mean in the service panel, and that #6 AWG is in addition to the service neutral, that is a superfluous Supply Side Bonding Jumper. And as such it is undersized per Table 250.102(C)(1). Probably best just to remove it.

Cheers, Wayne

 

[wwhitney]

Thank you for the reply! But it is acceptable to have two separate grounds rods that will be driven beside each other that do not have a direct connection? I thought they may have two separate potentials.

They do have a direct connection, via the service neutral conductor, which is used for all bonding on the utility side of the service disconnect.

Cheers, Wayne

 

[infinity]

There is no requirement to directly connect from one rod to the other. They are connected via the neutral.

 

[jaggedben]

If by "grounding bus bar" you mean in the service panel, and that #6 AWG is in addition to the service neutral, that is a superfluous Supply Side Bonding Jumper. And as such it is undersized per Table 250.102(C)(1). Probably best just to remove it.

Since it carries neutral current and is not otherwise required, it arguably violates 250.6(A) and is required to be removed.

 

[wwhitney]

Since it carries neutral current and is not otherwise required, it arguably violates 250.6(A) and is required to be removed.

I think if it were properly sized per Table 250.120(C)(1), you could just throw in an SSBJ if you felt like it. But since it is undersized and isn't large enough to be an SSBJ, as a conductor parallel to the service neutral conductor, it violates 310.10(G).

Cheers, Wayne

 

[jaggedben]

I still think 250.6 prohibits an otherwise-not-required SSBJ being connected to neutral at both ends. But perhaps that's more ambiguous if it's a correctly sized bonding jumper. (Which in the example it's not, since at 200A we can presume service conductors no smaller than 2/0 cu.)

 

[jaggedben]

Also relevant to the OP is 250.66(F)(2), which permits the two rods to have individual grounding electrode conductors.

 

[ccrump]

I still think 250.6 prohibits an otherwise-not-required SSBJ being connected to neutral at both ends. But perhaps that's more ambiguous if it's a correctly sized bonding jumper. (Which in the example it's not, since at 200A we can presume service conductors no smaller than 2/0 cu.)

The service conductors are sized to 4/0 and the grounds are sized to be 6 awg, according to our description. I attached the document we are given.

 

[jaggedben]

250.66(A) permits the GEC to each individual rod to be 6awg, so the 4/0 size is irrelevant to that.

To go into the weeds on why the green wire between the meter and the panel is not required....
Perhaps someone thinks it's required to bond together the two rods to comply with 250.50. However the Article 100 definition of 'Bonded' is plenty broad enough to allow the neutral to do that. And I'm not aware of any other section that explicitly requires a different type of bonding between electrodes.

So in my opinion, as mentioned above, remove the green wire between the meter and panel and it's code compliant.

 

[wwhitney]

The service conductors are sized to 4/0 and the grounds are sized to be 6 awg, according to our description. I attached the document we are given.

I excerpted page 2 as an image below (sorry if the text is too small now).

As Jaggedben and I were discussing, the green conductor in the middle PVC pipe segment (between the meter base and the service panel) should be removed.

Cheers, Wayne

 

[wwhitney]

I excerpted page 2 as an image below

Also, the text in the box next to the meter base is using the wrong terms. There are no grounding conductors (EGCs) on the utility side of the service disconnect. The green wires in the diagram are all Grounding Electrode Conductors, or (Electrode) Bonding Jumpers, or Supply Side Bonding Jumpers.

Cheers, Wayne

 

[infinity]

So in my opinion, as mentioned above, remove the green wire between the meter and panel and it's code compliant.

I agree. The NEC requires that when possible you need to eliminate all parallel paths for the neutral current. This is why the #6 needs to be removed.