Grounding a portable Gen set

[chiefelec]

I hope some one can help me with a disagrement I am having with an inspector. What I have is a trailer mounted 410KW gen set. the grounded bus and grounding bus are bonded together. there is a grounding electrode conductor running from the grounded bus to the frame of the trailer. there is a second grounding electrode conductor attached to the trailer at the same point as the first, this conductor is then attached to two 8 foot ground rods.

the dispute is the inspector has directed me to connect a continuous conductor from the ground rods to the grounded bus.

electricaly I do not think it makes a difference. but this is a portable gen set.

 

[Smart $]

I hope some one can help me with a disagrement I am having with an inspector...

...the dispute is the inspector has directed me to connect a continuous conductor from the ground rods to the grounded bus...

The inspector is correct. The conductors you call grounding electrode conductors are required to be continuous but can be spliced to meet the requirement using irrevisible compression connectors listed for the purpose or exothermic welding [other exceptions exist but involve busbars; see 250.64(C)]. If they are not spliced as such, the conductor from the grounded bus to the trailer frame is a bonding jumper, not a grounding electrode conductor.

 

[chiefelec]

The inspector is correct. The conductors you call grounding electrode conductors are required to be continuous but can be spliced to meet the requirement using irrevisible compression connectors listed for the purpose or exothermic welding [other exceptions exist but involve busbars; see 250.64(C)]. If they are not spliced as such, the conductor from the grounded bus to the trailer frame is a bonding jumper, not a grounding electrode conductor.

Thank you for your reply: yes the code states that the grounding electrode conductors is to be continuous but every portable/rential gen set I have been worked with has a grounding log located on the frame of the generator or in the case of a trailer mounted one the lug is on the trailer and that lug has a bonding jumper to the netural bus. the manufacture of the unit in question has told me this is common practice, but could not give me any referances to the code that thay are complying with.

 

[George Stolz]

I think this would make a good proposal for the 2011 NEC. I don't see the hazard created by using the frame of a trailer as a busbar in this application, but I don't believe the frame of the trailer with a couple lugs on it is a busbar.

I suppose the inspector is correct.