PV array pole grounding

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shortcircuit2

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The pole in this photo is isolated by the nylon bushing from the PV array system. I say there should be a bonding jumper to ground the pole according to the NEC. The engineer of this 82KW PV array system with tracking hardware says its not needed because the poles are in contact with the earth 12 feet deep.
 

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shortcircuit2 said:
The pole in this photo is isolated by the nylon bushing from the PV array system. I say there should be a bonding jumper to ground the pole according to the NEC. The engineer of this 82KW PV array system with tracking hardware says its not needed because the poles are in contact with the earth 12 feet deep.
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I am not sure that pole does require 'grounding', I think that wording in 690.43 tends to exclude the pole.

That said I think it is the AHJs call to make and if they say it needs to be grounded you and I both know that means a wire conductor per 690.43.
 
Thanks Iwire...
In reading 690.43 I'm directed to 250.110 where the term LIKELY to become energized is used. Is this the wording that excludes these isolated steel mounting poles from equipment grounding in this PV array?

shortcircuit2
 
690.43 Equipment Grounding. Exposed non?currentcarrying
metal parts of module frames, equipment, and conductor
enclosures shall be grounded in accordance with
250.134 or 250.136(A) regardless of voltage........
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IMPO the pole is not included in that list, but I also think an AHJ could decide the pole is 'equipment' but I think that is streaching that section.

I also wonder what would be 'likely to energize it?

The grounded metal frames of the modules? Seems unlikely and if we bond the poles to the frames to the pole if the frames do become energized the pole will be as well.


I really don't know the answer, if the AHJ asked me to install a few bonding jumpers I would just do it, OTH what if it was hundreds of poles in a large array? The outdoor rated lugs are like $4 or $5 each and you would need two at each pole along with labor and wire. It could get costly to do if not really required.
 
shortcircuit2 said:
Thanks Iwire...
In reading 690.43 I'm directed to 250.110 where the term LIKELY to become energized is used. Is this the wording that excludes these isolated steel mounting poles from equipment grounding in this PV array?

shortcircuit2
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The point I think that is somewhat eluding is that the array likely qualifies as a separate structure, or at the very least, an outside source. I'm fairly certain a grounding electrode system requirement kicks in. Under 250.50 "the poles are in contact with the earth 12 feet deep" make them a pipe electrode present at the structure, or outside source.
 
Smart $...
If we are to look at this installation from your perspective, then all the isolated posts of this PV array are grounding electrodes, as defined in 250.52(A)(2)(1), and would be required to be bonded together and be part of the grounding electrode system?
shortcircuit2
 
shortcircuit2 said:
Smart $...
If we are to look at this installation from your perspective, then all the isolated posts of this PV array are grounding electrodes, as defined in 250.52(A)(2)(1), and would be required to be bonded together and be part of the grounding electrode system?
shortcircuit2
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That is correct.
 
Smart$...

I've been thinking about your perspective.

I think that 690.47 (2008 NEC) modifies the requirements of 250 with respect to the grounding electrode system and 690.47(C)(6) mentions a common grounding electrode shall be permitted. This appears to be singular in nature and doesn't mention all present electrodes be used to create a grounding electrode system.

Would my perspective be correct?

shortcircuit2
 
shortcircuit2 said:
Smart$...

I've been thinking about your perspective.

I think that 690.47 (2008 NEC) modifies the requirements of 250 with respect to the grounding electrode system and 690.47(C)(6) mentions a common grounding electrode shall be permitted. This appears to be singular in nature and doesn't mention all present electrodes be used to create a grounding electrode system.

Would my perspective be correct?

shortcircuit2
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Has no bearing on the matter.

Look at 690.47(D).
 
Smart $... good point. Although it is from a different angle than I was heading. You have a keen eye for these code rules. So then these electrodes are required to be bonded to the PV frame(s) or structure according to 2008 NEC 690.47(D).

IMO...690.47(D) is intended to be supplementary for lightning protection and has no relation to the grounding electrode system. This section has been deleted for 2011.

I'm still trying to figure out if these poles, which we have determined to qualify as electrodes are required to be part of the grounding electrode system at the remote inverter...DC or AC?and which article of the 2008 NEC or the 2011 NEC may require this.

shortcircuit2
 
shortcircuit2 said:
Smart $... good point. Although it is from a different angle than I was heading. You have a keen eye for these code rules. So then these electrodes are required to be bonded to the PV frame(s) or structure according to 2008 NEC 690.47(D).

IMO...690.47(D) is intended to be supplementary for lightning protection and has no relation to the grounding electrode system. This section has been deleted for 2011.

I'm still trying to figure out if these poles, which we have determined to qualify as electrodes are required to be part of the grounding electrode system at the remote inverter...DC or AC…and which article of the 2008 NEC or the 2011 NEC may require this.

shortcircuit2
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Where are the inverters installed, i.e. are they part of the array structure, completely separate structure, or located in/on building served?
 
The 82KW inverter is on its on concrete pad about 50 feet from the array structure with its own grounding electrode, AC and DC disconnects, etc. It is about 100-200 feet from the building it serves.
 
shortcircuit2 said:
2008 nec
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Having all the pertinent information, my conclusion is that under the 2008 NEC, the array structure is required to have "Grounding electrodes" per 690.47(D). Yet 690.47(D) does not require the mounting poles to be said "electrodes".
 
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Smart $...

Thanks for bouncing this back and forth with me.
I spent 8 hours at a solar presentation by John Wiles the other day and I thought I knew a lot about solar before I went, and left realizing I know little. Solar is an ever evolving technology and as we all can see by the major changes in the NEC rules from cycle to cycle, there is still much to for us all to sort out.

shortcircuit2
 
shortcircuit2 said:
Smart $...

Thanks for bouncing this back and forth with me.
I spent 8 hours at a solar presentation by John Wiles the other day and I thought I knew a lot about solar before I went, and left realizing I know little. Solar is an ever evolving technology and as we all can see by the major changes in the NEC rules from cycle to cycle, there is still much to for us all to sort out.

shortcircuit2
Click to expand...

I am starting school for PV and wind installations next week. This site is going to be a great resource for me, I'm sure.
 
Someone needs to ask the PV array manufacturer for the purpose of the insulating bushings. It certainly would be less expensive to have a bolted or welded connection between the array and the poles, either of which would negate the requirement for bonding. There must be at least a perceived purpose to isolate the array and bonding the poles would remove the isolation.
 
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