grounding question and confusion

[Naptown]

What we are having is a conundrum. Because of differing adoptions of the various code books and local amendments changing further, not to mention interpretations of the codes by AHJ's It would be best to not offer advice on a forum pertaining to codes. They are different everywhere even when the same code is applied due to issues as stated above. What works for me in Maryland may not necessarily be to code in Massachusetts.
The only advice that would be valid would be to consult with the AHJ in your jurisdiction. Keep in mind that this is a forum open to everyone on the planet with the exception of a few hundred thousand spammers. The codes are extremely complex and generally not well understood by the public at large so please refrain in the future from advising people how to interpret the codes.

[n8huntsman]

I agree, and ultimately I will contact the building dept. As an owner builder I like to understand the different methods before contacting them because they tend to not want to talk to clueless people. It's been my experience that if I sound familiar with the concepts, they will work with me, tell me what they want to see, and actually let me slip on some things if it's not exactly perfect. Happend a couple times when I built my pool. I did not have a continuous bond wire from the rebar in the pool, to the rebar in the concrete and back to the ground rod. Instead I had a bare copper wire from the ground rod to the rebar in the concrete deck, then three feet away I another piece from the concrete deck to the pool rebar, not one continuous wire. They said, "Oh well. Too late now since your gunite guys are coming tomorrow."

[Sunking]

The codes are extremely complex and generally not well understood by the public at large so please refrain in the future from advising people how to interpret the codes.

That is why I usually refrain from even answering.

FWIW Mike Holt is probable one of the most knowledgeable person in the USA on NEC codes. He makes his living teaching code to engineers and electricians alike. I am a moderator on his Code Forum for grounding, low voltage and solar. Mike was published in ECM on the NEC changes with respect to 690 you might want to read as it highlights the recent changes. Most notable combining DC and AC GEC. However it is still required to bond the PV frames and racking directly to a GES with a dedicated GEC. f you stop and think about it makes perfect sense. Why would you want to dire a direct lighting strike through all your equipment, and into your AC panel. That would be nucking futs.

Source here

[n8huntsman]

That makes more sense. Since the enphase is converting DC to AC, is the green wire in the engage cable the GEC from the DC side? It also says to run the GEC through PVC. So you would run the pvc right alongside the EMT containing the common and hot wires?

[Sunking]

You would optimally want to run the GEC from the panels straight down to earth to a Ground Electrode. Keep in mind the EGC and GEC serve two different purposes.

The EGC purpose is to provide a planned path of low resistance to clear line faults. For example if either L1 or L2 were to short to the metallic case of the inverter, the fault current would be routed directly to the neutral conductor (grounded circuit conductor). The fault current will be very high, thus operating the over current protection device (aka fuse or breaker)

The GEC purpose is two fold but its primary purpose is to provide a low resistance path for high voltage directly to earth to be discharged. High voltages would be lightning or over head high voltage utility lines that might fall on the panels. You do not want to route that through your equipment or your home wiring.

[FloridaSun]

You would optimally want to run the GEC from the panels straight down to earth to a Ground Electrode. Keep in mind the EGC and GEC serve two different purposes.

The EGC purpose is to provide a planned path o flow resistance to clear line faults. For example if either L1 or L2 were to short to the metallic case of the inverter, the would route the fault current directly to the neutral conductor (grounded circuit conductor). Th efault curren twill be very high, thus operating the over current protection device (aka fuse or breaker)

The GEC purpose is two fold but its primary purpose is to provide a low resistance path for high voltage directly to earth to be discharged. High voltages would be lightning or over head high voltage utility lines that might fall on the panels. You do not want to route that through your equipment or your home wiring.

After the initial confusion of this thread with too many cooks in the kitchen I think I've finally got a better grasp on grounding... which isn't that different than my original thoughts but your explanations clarify. Sunking, you're also a Groundking and an excellent instructor

[shortcircuit2]

That is why I usually refrain from even answering.

FWIW Mike Holt is probable one of the most knowledgeable person in the USA on NEC codes. He makes his living teaching code to engineers and electricians alike. I am a moderator on his Code Forum for grounding, low voltage and solar. Mike was published in ECM on the NEC changes with respect to 690 you might want to read as it highlights the recent changes. Most notable combining DC and AC GEC. However it is still required to bond the PV frames and racking directly to a GES with a dedicated GEC. f you stop and think about it makes perfect sense. Why would you want to dire a direct lighting strike through all your equipment, and into your AC panel. That would be nucking futs.

Source here

Sunking... your posted picture supports my postion on this issue.Thankyou. It depicts the "MARKED DC GROUNDING CONDUCTOR CONNECTION POINT" right there in the inverter. Some may say well why are there 2 terminals? Because this product is designed for widespread use throughout the world.

Further if you read the article from your posted link, it is in line with my comments:

Equipment Bonding
Unfortunately, Art. 690 retains the use of “grounding” where it means “bonding” (see Art. 100 definitions). Wherever you see “equipment grounding,” such as in 690.43 (or elsewhere in the NEC), the intent is equipment bonding. However, the 2011 NEC provided much better formatting of the equipment “grounding” provisions of Art. 690, Part V. When multiple requirements or provisions are in a single section, a “list” format is often easier to read and understand. Section 690.43 now reflects that fact. This revision also includes some technical changes. For example:
• Subsection (C) now requires that metal mounting racks be identified as equipment grounding conductors (EGCs) or have a bonding jumper(s) or devices installed between the separate metallic sections (Fig. 4). In addition, the metallic racks must be connected to the grounding system, which can be done via an equipment grounding conductor.
• Subsection (D) (added with the 2011 revision) requires that devices for securing PV modules be identified for equipment grounding if they’re used as an EGC.
Grounding electrode system
In contrast to “equipment grounding conductor,” the NEC really does mean “grounding” when it talks about the grounding electrode system. The key changes to requirements for PV grounding electrode systems [690.47] are:
• Section 690.47(B) now is clear that you can use a common grounding electrode conductor (GEC) to ground multiple inverters. This concept isn’t new to the NEC; similar provisions are in 250.30 for separately derived systems.
• Section 690.47(C) underwent extensive revision, with the intention of incorporating the concepts of the 2005 and 2008 editions into clear, easily understandable text.
• Section 690.47(D) wasn’t revised; it was deleted. It required ground and pole-mounted PV arrays to have a grounding electrode. The intention in the 2008 revision was for this to be optional, but the language used made it mandatory. Deleting Sec. 690.47(D) makes the rule optional again.
All of 690.47(C) is worth reading closely, but let’s look at its last paragraph. Subsection 690.47(C)(3) allows you to use a single conductor as the DC grounding electrode conductor (GEC) as well as for the AC equipment grounding conductor. This GEC must be unspliced (or irreversibly spliced). Run it from the marked direct-current grounding electrode connection point along with the alternating-current circuit conductors to the grounding bus bar in the associated alternating-current equipment.
You must size this GEC to the larger of 250.122 or 250.166, and install it per 250.64(E).
To prevent inductive choking of grounding electrode conductors, ferrous raceways and enclosures containing grounding electrode conductors must have each end of the raceway or enclosure bonded to the GEC per 250.92(B) [250.64(E)]. Nonferrous raceways don’t need to meet this requirement. To save a lot of time and effort, install the grounding electrode conductor in PVC conduit suitable for the application [352.10(F)].

Also, many of the questions posted on this forum touch on code issues. The forum should allow open discussion on code application for the safety of its visitors, many who will try to install PV themselves. As much as I think I know, I would not try to do a system myself yet.

As far as Mike Holt, he is a well respected code specialist and I respect his views and interpretations. But, I do not live by his interpretations exclusively; I take them as informational and conclude decisions on code from all sources in my own interpretation of a code rule. Not all rules are black and white; many are “grey”…

I admit I was wrong about upsizing the equipment grounding conductor when upsizing the ungrounded conductors for voltage drop when applied to PV source and output circuits. But I believe I have it straight about the grounding electrode system issue.

If you would like this discussion to end here on that note, that’s fine by me. But let’s take this over to Mike’s forum and get it straight from the experts there.


shortcircuit

[Sunking]

Also, many of the questions posted on this forum touch on code issues. The forum should allow open discussion on code application for the safety of its visitors, many who will try to install PV themselves. As much as I think I know, I would not try to do a system myself yet.

As far as Mike Holt, he is a well respected code specialist and I respect his views and interpretations. But, I do not live by his interpretations exclusively; I take them as informational and conclude decisions on code from all sources in my own interpretation of a code rule. Not all rules are black and white; many are “grey”…

But let’s take this over to Mike’s forum and get it straight from the experts there.

My issue is very simple. This is a DIY forum, and not a professional forum period. This is why I usually ignore such threads. DIY's cannot understand the answers or even know the right questions to ask. As for Mike Holt I have worked for him about 12 years. Mike brought me in the NEC Code Panel 9 in 2001 and I served up until 2010. Got to be to time consuming. I have been a Moderater on Mike's Forum since 2003, and still check in there once in a while. With that said Mike's Forum is for professionals only. DIY's are not allowed to be members or ask questions. Mike has been sued a few times from DIY's sneaking in and asking questions, and ended up either getting themselves hurt or damaged equipment. No one has ever one a court case, but none the less has cost Mike a lot of money defending himself.

So I agree with Rich code issues and actual installation practices should not be discussed here. So from this point forward I will refrain from answering code or installation issues. Just a matter of time before this forum finds itself in court.

[russ]

What we are having is a conundrum. Because of differing adoptions of the various code books and local amendments changing further, not to mention interpretations of the codes by AHJ's It would be best to not offer advice on a forum pertaining to codes. They are different everywhere even when the same code is applied due to issues as stated above. What works for me in Maryland may not necessarily be to code in Massachusetts.
The only advice that would be valid would be to consult with the AHJ in your jurisdiction. Keep in mind that this is a forum open to everyone on the planet with the exception of a few hundred thousand spammers. The codes are extremely complex and generally not well understood by the public at large so please refrain in the future from advising people how to interpret the codes.

To repeat what Naptown pointed out - any followup will be deleted.

[sirsparky]

Pardon me but I'm new to this forum. Are you suggesting that nobody should post and this forum be shutdown because of liability?
Just about everything on this board is either installation or code related. If so, what's the point of the forum?

[Naptown]

Pardon me but I'm new to this forum. Are you suggesting that nobody should post and this forum be shutdown because of liability?
Just about everything on this board is either installation or code related. If so, what's the point of the forum?

Generalities are one thing, specifics considering the differences in code cycles and the potential confusion of a non pro are another.

[solareagle]

In case any other homeowners are reading this...

Even if you are self installing, I highly recommend paying the $200-$400 for a set of plans. You need to follow the single line diagram. Find a solar PV designer and ask them to do it.

[n8huntsman]

In case any other homeowners are reading this...

Even if you are self installing, I highly recommend paying the $200-$400 for a set of plans. You need to follow the single line diagram. Find a solar PV designer and ask them to do it.

I followed the Enphase single line drawing found here: http://enphase.com/wp-uploads/enphas..._M215_240v.pdf
Had my inspection last week and passed with no findings. It was very easy. As an engineer I am very comfortable with creating my own drawings and didn't need to spend the money to have someone else do it, however, if you are not comfortable creating them, 200 to 400 isn't bad.

[SunEagle]

I followed the Enphase single line drawing found here: http://enphase.com/wp-uploads/enphas..._M215_240v.pdf
Had my inspection last week and passed with no findings. It was very easy. As an engineer I am very comfortable with creating my own drawings and didn't need to spend the money to have someone else do it, however, if you are not comfortable creating them, 200 to 400 isn't bad.

The drawing doesn't have any title block or information as to who designed or drew it.

It doesn't show equipment or manufacturer information. There aren't any wire sizes or insulation type and it doesn't show any external disconnect between the solar panels and circuit breaker panel.

I am surprised an Inspector would accept it.

[n8huntsman]

The drawing doesn't have any title block or information as to who designed or drew it.

It doesn't show equipment or manufacturer information. There aren't any wire sizes or insulation type and it doesn't show any external disconnect between the solar panels and circuit breaker panel.

I am surprised an Inspector would except it.

I didn't use that for permitting purposes. I drew up my own drawings, with borders and all the data mentioned above. I've attached it in case anyone else wants to use it as a reference.