Service Grounding Question - Multiple Tenants

[Designer69]

Please see attached pic. Basically want to know if I can just ground the electrical wireway as shown or I need to ground each meter ckt. breaker individually?

Thank You

 

[nickelec]

Each ckt breaker individually

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[electrofelon]

Please see attached pic. Basically want to know if I can just ground the electrical wireway as shown or I need to ground each meter ckt. breaker individually?

Thank You View attachment 20268

see 250.28(D)(2) and 250.64(D) and 250.92. Let us know if that answers the question.

 

[electrofelon]

Each ckt breaker individually

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Certainly some vagueness as to what he means by "ground"

 

[infinity]

What is the "building ground" in the graphic?

 

[Designer69]

I meant main service ground.

The main service ground. I'm not sure if it's done at the wireway or the individual ckt breakers. I will review those NEC articles, thank you.

Building ground is building steel & water pipe

 

[electrofelon]

I meant main service ground.

The main service ground. I'm not sure if it's done at the wireway or the individual ckt breakers. I will review those NEC articles, thank you.

Building ground is building steel & water pipe

With multiple service equipment enclosures, you have several options, basically land the GEC at a common location before the service entrance conductors split, or use taps to each enclosure. 250.64(D) is where to look. Often for that type of setup the "GEC busbar" (250.64(D)(1)(3)) is convenient.

 

[jaggedben]

Please see attached pic. Basically want to know if I can just ground the electrical wireway as shown or I need to ground each meter ckt. breaker individually?

Thank You View attachment 20268

You can do either, but not both, and if you run grounding electrode conductors from each circuit breaker enclosure they must all be connected to the same electrode(s).

 

[kwired]

I meant main service ground.

The main service ground. I'm not sure if it's done at the wireway or the individual ckt breakers. I will review those NEC articles, thank you.

Building ground is building steel & water pipe

I think you are asking where to connect the grounding electrode conductor?

As mentioned there is more then one way to do it in multiple service disconnect applications. Both methods you are questioning are acceptable, maybe with more details then you mentioned though.

 

[infinity]

You can do either, but not both, and if you run grounding electrode conductors from each circuit breaker enclosure they must all be connected to the same electrode(s).

Just curious what would prohibit one from doing both parallel current paths?

 

[jaggedben]

Just curious what would prohibit one from doing both parallel current paths?

Your question could be interpreted a couple different ways depending on whether you mean to refer to different paths to earth as 'parallel' or if you are just referring to parallel paths to the same GES.

For the former interpretation, all electrodes in the system must be connected together, you cannot have separate paths to earth. 250.50. Note the OP's diagram seems to show individual GECs to separate-not-bonded-together electrodes, which would violate that section. Those individual GECs are only allowed if they all go to the same GES.

As far as parallel paths to the bonded-together GES, I think objectionable current, 250.6, would prohibit you from using both the methods in 250.64(D)(2) and (3), and this corroborated by the fact that 250.64(D) starts out by saying that the connections "shall be made in accordance with 250.64(D)(1), 250.64(D)(2), or 250.64(D)(3)." (Emphasis added.) Indeed, I would say that 250.6 would prohibit what is described in 250.64(D)(1) and 250.64(D)(2) if those same sections did not explicitly describe those methods as being permitted.