Generator (neutral) grounding/bonding...

[shockking]

Trying to settle an age old debate in the office... What is wrong with these arrangements? What code section is violated? What risk is introduced?



Base case is the un-modified figure from Mike Holts, showing a generator and transfer switch with solidly bonded neutral.
Case 1 shows adding a ground rod at the transformer. Ground rod is only connected to the generator ground (not the neutral). The neutral is only bound to ground at the service panel.
Case 2 shows case 1 with the addition of a bonding jumper from generator neutral to new ground rod. There are two neutral-to-ground connections.

 

[dkidd]

Normal neutral current will flow over conductive ground iitems.

 

[augie47]

Also a violation of 250.24(A)(5)
Load-Side Grounding Connections. A grounded conductor shall not be connected to normally non–current-carrying metal parts of equipment, to equipment grounding conductor(s), or be reconnected to ground on the load side of the service disconnecting means except as otherwise permitted in this article.

 

[shockking]

Makes sense for 'case 2'.
What about 'case 1'? Is that what you mean about 250.24(A)(5)?

 

[augie47]

Makes sense for 'case 2'.
What about 'case 1'? Is that what you mean about 250.24(A)(5)?

Case 1 at one time was a requirement from some generator manufacturers. If it is considered a auxiliary electrode per 250.54 there is no problem.

In case 2, you are connecting the grounded conductor to the grounding conductor and earth, a violation as noted in the wording and, a dkidd points out, it also introduces objectionable current flow.

 

[shockking]

Got it. Thank you both.