NEC 2017 section 250.30(A)(4)

[hhsting]

Please see attached sketch. Outside feeder goes into electrical shed fused disco. The fused disco has grounding electrode system accordance with 250.32. The grounding electrode are ground rods and concrete encased electrode conductor and each has grounding electrode individually from the fused disco. The fused disco feeds delta to wye transformer. The transformer then feeds panelboard.

Question:

NEC 2017 Section 250.30(A)(4) says to use building or structure grounding electrode system. In the attached sketch should grounding electrode conductor from transformer go to ground rods, concrete encased electrode or it should go to ground bus in the fused disconnect or something else in order to comply with NEC 2017 Section 250.30(A)(4)? Which one? If something else then what?

 

[electrofelon]

see 250.30(A)(5)

(5) Grounding Electrode Conductor, Single Separately
Derived System. A grounding electrode conductor for a
single separately derived system shall be sized in accordance
with 250.66 for the derived ungrounded conductors.
It shall be used to connect the grounded conductor of the
derived system to the grounding electrode as specified in
250.30(A)(4).

In practice, I would likely use a "GEC busbar" to connect everything to.

 

[hhsting]

see 250.30(A)(5)

(5) Grounding Electrode Conductor, Single Separately
Derived System. A grounding electrode conductor for a
single separately derived system shall be sized in accordance
with 250.66 for the derived ungrounded conductors.
It shall be used to connect the grounded conductor of the
derived system to the grounding electrode as specified in
250.30(A)(4).

In practice, I would likely use a "GEC busbar" to connect everything to.

I dont follow. Did you miss post title? I am aware of 250.30(A)(4). Yes i understand that GEC needs to connect from transformer to grounding electrode but that is not the question post #1. 2017 version of 250.30(A)(4) says to connect to building or structural grounding electrode system. What point is building or structural grounding electrode system in the post #1 attachment ground rods, concrete encased electrode or internal fused disco ground bus or something else? I dont have external GEC busbar either. See sketch and see post #1 question.

 

[hhsting]

does anyone know or have opinion?

 

[Greentagger]

Use the GES to ground the transformer. You’re done.
Now about the location of your disconnecting means .According to your “sketch” , does this location comply with 225.32?

 

[hhsting]

Use the GES to ground the transformer. You’re done.
Now about the location of your disconnecting means .According to your “sketch” , does this location comply with 225.32?

Yes it comply 225.32. But what is GES? where do I attach my transformer grounding electrode from the transformer? Does it go to ground rods, concrete encased or fused disco intern ground bus? Where is the GES in this case?

 

[Greentagger]

You are not attaching them. The electrician in the field will do the installation. You are Plan Reviewer?

 

[hhsting]

You are not attaching them. The electrician in the field will do the installation. You are Plan Reviewer?

Yes plan reviewer. Is it building GES or structure GES?

 

[ActionDave]

Yes plan reviewer. Is it building GES or structure GES?

Yes.

 

[hhsting]

Yes.

Right I meant which one building or structure GES in above case?

 

[electrofelon]

I dont follow. Did you miss post title? I am aware of 250.30(A)(4). Yes i understand that GEC needs to connect from transformer to grounding electrode but that is not the question post #1. 2017 version of 250.30(A)(4) says to connect to building or structural grounding electrode system. What point is building or structural grounding electrode system in the post #1 attachment ground rods, concrete encased electrode or internal fused disco ground bus or something else? I dont have external GEC busbar either. See sketch and see post #1 question.

I don't know what else to say or what there is to not follow. (A)(5) says "To the grounding electrode as specified in
250.30(A)(4)"

Let the installer worry about The specifics of making the actual physical connection.

 

[hhsting]

I don't know what else to say or what there is to not follow. (A)(5) says "To the grounding electrode as specified in
250.30(A)(4)"

Let the installer worry about The specifics of making the actual physical connection.

Ok thanks