Equipment Grounding Conductors in with Service Entrance Conductors.... Is this something new?

Keystone

Member
Recently on a design build project, our electrical engineer has indicated we are to provide a properly sized equipment grounding conductors along with the secondary service lateral / feeders between the 3” ground bar located within the utility pad mount transformer, to the main switch gear.
We are also directed to eliminate the bond connection between the neutral and ground bar of the main switch gear, and provide all the grounding measures we typically would provide on a normal commercial project. These would include a NEC sized ground conductor to the main water line, building steel, and an external grounding triad.
In this particular case, it involves a 2000 Ampere, 120/208 VAC 3-Phase, 4-Wire underground service consisting of eight (8) sets of 4 pieces of 600 MCM Aluminum (AL) type XHHN, and a #4/0 AL ground in a 4" PVC Sch. 40.
I strongly disagree that the primary grounding of the service is derived by the bonding jumpers between the neutral terminal and grounding of the utilities pad mount transformer. Furthermore, I believe the "grounded" conductors or "neutral" conductor of the 3 phase / 4 wire system is all that is needed between the utility transformer and main distribution board. The bonding connection should be installed and adding equipment is nothing more than a redundant feature that is not required by the NEC.
I've installed hundreds of underground service laterals in over forty years in this trade and only seen this one other time. And on that occasion, the local utility indicated they did NOT want equipment grounds tied back to their ground bar.
Is this something new or have I been doing this wrong for all these years? I've never had a service fail an inspection so I'm wondering if the engineer is correct or crazy, if this is something new, or I just don't understand electricity anymore.....

Regards, David A.
 

augie47

Moderator
Staff member
Location
Tennessee
I have on occasion seen an engineer show a grounding conductor back to the POCO pad ground rods.
I am in ageement that the grounding bonding, etc. should be completed in youir service gear.
 

infinity

Moderator
Staff member
Location
New Jersey
Occupation
Journeyman Electrician
There should not be 5 conductors in the 4" PVC there should only be 4 conductors. The #4/0 ends up in parallel with the neutral and is not required or needed for anything.
 

GoldDigger

Moderator
Staff member
Were this a service feed overhead, there wouldn't be a ground at the transformers!
Given that the transformer is a POCO transformer, I would expect a POCO ground to the transformer itself, along with a bond to the neutral of the secondary if there is one. The only options if the POCO secondary is delta would be ungrounded or grounded via a zig-zag transformer.
 

texie

Senior Member
Location
Fort Collins, Colorado
Occupation
Electrician, Contractor, Inspector
What the engineer is proposing violates both the NEC and the NESC. The POCO will never go along with this either nor should the AHJ. If he persist I would file a complaint with the PE licensing folks.
 

Keystone

Member
That is correct, the Delta-Wye transformer contains a bonding jumper between the "X" terminal and the main ground bar located in the transformer pad cavity. In my opinion, there is no need to add equipment grounds between the main service entrance equipment and utility transformer.
 

augie47

Moderator
Staff member
Location
Tennessee
A bit of an oddity in the Code, if the transformer is part of the premises wiring system (a SDS) as opposed to being a POCO transformer, a supply side bonding jumper IS required unless the installation is covered by the exceptions which is often the case.
 

texie

Senior Member
Location
Fort Collins, Colorado
Occupation
Electrician, Contractor, Inspector
A bit of an oddity in the Code, if the transformer is part of the premises wiring system (a SDS) as opposed to being a POCO transformer, a supply side bonding jumper IS required unless the installation is covered by the exceptions which is often the case.
True, but I think we are led to believe that this is a POCO service transformer. But good point.
 

texie

Senior Member
Location
Fort Collins, Colorado
Occupation
Electrician, Contractor, Inspector
The application in question is a public utility owned transformer
Noted. You need to stand your ground on this as it is not compliant to do what the engineer is proposing as I mentioned previously. It is urban legend to believe that you can install something that violates the code just because the P.E. said to.
 
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