GEC to N or G?

charlie b

charlie b

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Lockport, IL
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Semi-Retired Electrical Engineer
Please tell me that I am right in saying that in the main service panel the Grounding Electrode Conductor should be connected to the Neutral bus, not the Ground bus. I ask because, once again, I am reviewing a design package that shows the N and G bonded to each other, with the GEC connected to G. And once again it shows up in a "standard" detail that is included in the drawing package with no thought being given to it by the design engineer.

I know that it would take a myriad of things to go wrong before a GEC connection to the G bus could create a safety hazard. But I believe that there is nothing wrong with doing things right.

My real question is what would you do if you received a design package that showed the GEC connected to G?
 
Here is the wording, 250.24:

(1) General. The grounding electrode conductor connection shall be made at any accessible point from the load end of the overhead service conductors, service drop, underground service conductors, or service lateral to, including the terminal or bus to which the grounded service conductor is connected at the service disconnecting means.
 
The way I read it, if it's a factory non removable connection (such as suitable for use only as service equipment equipment) between two bars, then the gec can land on either. If it's an optional or removable connection, and the gec needs to land on the same bus as the grounded conductor.
 
It is clearly the grounded service conductor that the GEC must connect to, either directly or by wire or other conductor, and not through enclosure metal, just like for the neutral current pathway.
 
electrofelon said:
The way I read it, if it's a factory non removable connection (such as suitable for use only as service equipment equipment) between two bars, then the gec can land on either. If it's an optional or removable connection, and the gec needs to land on the same bus as the grounded conductor.
Click to expand...
Is large equipment the MBJ is just bolted to the neutral from the EGC bus. It's not required to be non-removable.

250.24(A)(4) Main Bonding Jumper as Wire or Busbar.
Where the main bonding jumper specified in 250.28 is a wire or busbar and is installed from the grounded conductor terminal bar or bus to the equipment grounding terminal bar or bus in the service equipment, the grounding electrode conductor shall be permitted to be connected to the equipment grounding terminal, bar, or bus to which the main bonding jumper is connected.
Click to expand...
 
2023 NEC

General Rule:
1. 250.24 Grounding of Service-Supplied Alternating-Current System.

(A) System Grounding Connections. A premises wiring system supplied supplied by a grounded ac service shall have a grounding electrode conductor connected to the grounded service conductor, at each service, in accordance with 250.24(A)((1)-(A)(4).

(1) General. The grounding electrode connection shall be made at any accessible point from the load end of the overhead service conductors, service drop, underground service conductors, or service lateral to the terminal bus to which the grounded service conductor is connected at the service service disconnecting means.

I am skipping 2 & 3 - they are not necessary for this topic.

4. Main Bonding Conductor as a Wire or Busbar. If the main bonding jumper specified in 150.28 is a wire or busbar and is installed from the grounded conductor terminal bar or bus to the equipment ground terminal bar or bus in the service equipment, the grounding electrode conductor shall be permitted to be connected to the equipment ground terminal bar or bus to which the main bonding jumper is connected.

Notice this information is located in Art 250 PART II System Grounding, and not in Art 250 Part III Grounding Electrode System and Grounding Electrode Conductor

This confuses a number of guys/gals as the would think it belongs in Part III. But... the connections are made at the System, hence Part II

There are 4-1/2 pages of requirements in Part III, do not forget to becoming familiar with those as well.
 
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