Non separately derived generator grounding question

[hhsting]

I have non separately derived generator with all 3 poles ATS. However, I have drawing that shows generator grounding detail as below.

I am confused how can non separately derived system have grounding as shown below snapshot. Would this be allowed based off of NEC 2017? If yes then which NEC 2017 Article?

 

[jaggedben]

It's not clear to me that the diagram shows system grounding, i.e. connecting the electrode to the grounded conductor/neutral. If it's just earthing the generator frame and housing then that could be to satisfy 250.32 or done under 250.54 if the manufacturer wants the generator frame and housing grounded. To say if there's anything wrong we need more info on what the 'generator ground point' (item 6) connects to, and whether neutral-to-ground bonding can be installed or removed in the generator.

 

[hillbilly1]

As long as it doesn’t connect to the neutral, the EE can spec that. He may be classifying it as a structure, but other than that, not required by the NEC.

 

[Seven-Delta-FortyOne]

You say 3 pole, is this a single phase, or 3 phase generator?

I see specs where the owner wants additional ground rods and earthing at the generator, even though it’s not necessary or required.

 

[infinity]

I agree with the others. It appears that there is no connection to the neutral so there is no issue with bonding the frame or the enclosure to an electrdoe.

 

[qcroanoke]

He may be classifying it as a structure,

I thought that nonsense went away?

 

[hillbilly1]

I thought that nonsense went away?

Maybe @Dennis Alwon will chime in, I know it was something North Carolina was big on at one time.

 

[Dennis Alwon]

I thought that nonsense went away?

It did.

Structure.
That which is built or constructed, other than equipment.

 

[infinity]

It did.

The additional words "other than equipment" helped somewhat with the scope of the definition. What's depicted in the drawing in the OP is clearly not a structure.

 

[don_resqcapt19]

I thought that nonsense went away?

Something like that has been required by the project specifications for every generator I have ever installed, however the smallest I have installed was 100 kW.

 

[Elect117]

I thought generators always needed their case to be connected to a grounding electrode.

But now I can't find why I thought that.

Maybe it was for static or similar for the gas tank?