Bonding the Neutral in an Industrial Control Panel

[RUWired]

The article is 250.30(A). Regrounding past the point of grounding. The jumper at the transformer is the point of grounding, anything past that point should be isolated. The sketch is something i created.

Rick

 

[dbaird]

reply

reply

From Allen-Bradley Pub. 1770-4.1

 

[RUWired]

From Allen-Bradley Pub. 1770-4.1

I see in the AB drawing they require a connnection to an electrode where the NEC allows the incoming equipment ground in place of the electrode.
Rick

 

[Smart $]

I see in the AB drawing they require a connnection to an electrode where the NEC allows the incoming equipment ground in place of the electrode.
Rick

Isn't ising the equipment ground in effect connecting to an electrode?

 

[RUWired]

Yes it is but currently only allowed to be used with transformers 1000va or less. Why would AB require an electrode if not nec required. I don't see a significant amount of control transformers needing to be any larger than a 1000 va.

Rick

 

[Smart $]

Yes it is but currently only allowed to be used with transformers 1000va or less. Why would AB require an electrode if not nec required. I don't see a significant amount of control transformers needing to be any larger than a 1000 va.

Rick

I think you missed my point. An EGC in a typical premises wiring system is in effect connected to the grounding electrode system (i.e. the EGC provides a low-impedance path to the GES).

 

[RUWired]

I understood what you were saying. The equipment ground conductor is tied to the GES back at the source, but the AB drawing is calling for a "GEC". If the drawing didn't call it a GEC and just said connect it to the GES, i would agree that the equipment ground conductor is satisfying the requirement.

 

[Smart $]

I understood what you were saying. The equipment ground conductor is tied to the GES back at the source, but the AB drawing is calling for a "GEC". If the drawing didn't call it a GEC and just said connect it to the GES, i would agree that the equipment ground conductor is satisfying the requirement.

Aye...

...but it appears, though not noted, the xfmr is over 1000VA and qualifies as an SDS.

 

[RUWired]

Aye...

...but it appears, though not noted, the xfmr is over 1000VA and qualifies as an SDS.

Looking at the rest of the publication,page 9 of 20, http://literature.rockwellautomation.com/idc/groups/literature/documents/in/1770-in041_-en-p.pdf they are using the GEC for equal potential although the equipment ground conductor does the same.

Rick