Point of Connection, Commentary Note

[ggunn]

Wow. You have a lot to deal with here.

In the first place, I cannot fathom why a contractor would cultivate such an adversarial relationship with the inspector who has the power to red tag systems he builds. If you and he disagree on points of code, the burden of proof is on him to prove compliance, and namecalling and bluster do not count as proof.

In the second place, we can go (and have gone) round and round as to whether a supply side tap for a PV system is a service entrance, but in this case since the panel in the garage services the loads in the garage as well as providing a connection point for the PV system, I do not see how you can consider it not to be a service entrance. In some jurisdictions all the PV feeding a single meter must have one point of contact (one red handle) with the grid; does your organization have a policy about that?

Also, it wasn't clear to me what the contractor wants to do with the power output of the inverter which is hot when the grid is down and there is illumination of the array, but it must not connect to the panel where the PV system is connected to the grid. It must be completely isolated from the grid at all times.

All that said, it appears to me that you might could use some help beyond what you can get from an internet forum. Are there other inspectors with more experience dealing with PV with whom you could consult?

 

[jaggedben]

The garage has no other power the 100 feeder from the 200 amp exterior house panel to the garage brings the normal utility power to the garage but is serving the duel purpose of greating a tie to the 200 amp exterior ?PV panel? at the house using the 100 amp feeder between the house and the garage.

The PV system is DC. Everything being discussed is new and installed by the PV contractor. The PV system in the basement of the house, the new 200 amp exterior panel, the new 100 amp feed between the panels (exterior house and garage) the 30 amp breaker, at the exterior house panel, The new 100 amp panel in the garage, the 30 amp breaker in that panel for the garage array connection point, the new PV system in the garage.

Seems like what I said...They are using this opportunity to add power to the garage even though it's not necessary for the PV system. Otherwise there's no reason the inverter circuit couldn't just be connect to 30A breaker in the new 200A Panel. If a disconnect is necessary at the garage that could be a safety switch.

This contractor only uses PVC conduit for his systems and claims using metal conduit will create a ?shocking hazard? in the DC systems. He claims there are code changes in 2011 and 2014 that allow the DC without metal conduit into the garage and the house. Well at least he claims there are code changes that make his installation totally compliant with the code.

There are no such code changes. The 2011 added MC cable as an allowable method inside a building, along with a bunch of conditions. (690.31(E)). Otherwise only metal raceway is allowed (although it can be flexible). If it's outside he can use any method that's approved for the location, which might not include PVC in direct sunlight.

I not buying the PVC explanation for the DC entering the buildings I cannot see how the metal conduit would cause a hazard if properly grounded.

I don't buy it either. Using PVC just means that a potential ground fault, while perhaps presenting less danger in the short term, goes undetected and becomes a bigger problem in the long term.

I questioned him about the grounding for his DC array and he claims because it is an ungrounded DC System only the equipment grounding is required at the array and no grounding electrode system is required at the array since he is using the AC grounding electrode system at both the exterior 200 amp panel at the house, for the house array and the interior 100 amp panel at the garage for the garage array.

That's pretty much fine under the 2011 code. The 2008 and 2104 codes require an array electrode but in my opinion that is an unnecessary and even perhaps dangerous requirement. (See here.)

The grounding conductor from inverters to AC electrode should be a #8 minimum under 2011 code but is allowed to be sized for 250.122 under the 2014 code. In either case it's required to be continuous or irreversibly spliced as far as the 'associated AC equipment', whatever that means. In my opinion the practical safety consequences in this area are nil for systems of this size as long as all equipment grounding meets normal equipment grounding requirements.

 

[david]

That's pretty much fine under the 2011 code. The 2008 and 2104 codes require an array electrode but in my opinion that is an unnecessary and even perhaps dangerous requirement. (See here.)

I watched the video, if the 2008 code and 2014 code require the DC array earthed what would be the problem grounding to the electrode for the garage and at the house earthing the array at the service grounding electrode. You would not be creating additional points and still would be meeting the requirement to earth the DC array?

The second thing from the video is the garage has an electrode tied to the equipment grounding from the 100 amp panel installed by the PV contractor. Are you suggesting bonding the metal frame of the array to that existing electrode would be adding an additional point of earthing, and by bonding to that would be creating a hazard?

I understand aux. electrodes would create additional points, but how do existing required electrodes create this additional safety concerns

 

[david]

I get back to this, my sister in-law just called, I need to go to my brothers house. I appreciate the feed back I have much to consider and it is hard when the installer is designing from codes that are more recent than the state decided to adopt.

I can not defer to any other authority that burden is mine, I have been reading a lot on solar and other systems in the past year, As you are aware several points of view on some of the subject matter.

I do not see an allowance for the PVC conduit.

I was not aware that the service entrance not service entrance was a hot subject.

and I was not aware that there was a debate over a grounding electrode system for the DC portion of the Array.

Thank you all for your time

..............David...........

 

[GoldDigger]

Since the NEC is for the most part a restrictive code, if you do not find a prohibition on using PVC it would usually be permitted.
Now if you are looking at a 2008 code section that requires metallic raceway or metal jacketed cable, you are correct in rejecting PVC.
What code section are you starting from?

 

[jaggedben]

I watched the video, if the 2008 code and 2014 code require the DC array earthed what would be the problem grounding to the electrode for the garage and at the house earthing the array at the service grounding electrode. You would not be creating additional points and still would be meeting the requirement to earth the DC array?

I don't see a problem. You didn't mention the electrode at the garage before but of course that's required by 250.32.

The second thing from the video is the garage has an electrode tied to the equipment grounding from the 100 amp panel installed by the PV contractor. Are you suggesting bonding the metal frame of the array to that existing electrode would be adding an additional point of earthing, and by bonding to that would be creating a hazard?

Bonding the array to the building grounding electrode system, usually through the inverter using normal equipment grounding methods, should be good enough. What is not required under 2011, and in my opinion should not be required even though it's required in other code cycles, is additional grounding electrodes dedicated to a roof-mounted array.

 

[jaggedben]

Since the NEC is for the most part a restrictive code, if you do not find a prohibition on using PVC it would usually be permitted.
Now if you are looking at a 2008 code section that requires metallic raceway or metal jacketed cable, you are correct in rejecting PVC.
What code section are you starting from?

For PV (DC) circuits inside a building...
I don't have the 2008 code, but looking at 690.31(E) in the 2011 code the phrase "shall be contained in metal raceways, or metal enclosures..." is not marked as revised. Inserted into the middle is a revision: "[or] Type MC metal-clad cable that complies with 250.118(10)...". These are thus the only wiring methods permitted for PV circuits inside a building, and the 2008 AFAIK only allows metal raceways or enclosures. (That would include FMC and LFMC).

In the 2014 this section was redesignated 690.31(G) but otherwise not substantively changed.

For exterior, I believe that 352.12(D) prohibits using most PVC on roofs, albeit implicitly. Otherwise it's okay for exterior.

 

[david]

Mike Holt think's it's not a service disconnect, although he states it's a good idea to follow 230. Marvin Hamon (EE and writer for Solar Pro magazine) thinks 230 applies, although he acknowledges this is not explicit in the code. Just to cite a couple examples.

I went to Solar Pro Site and read issue 4.3 Apr/May and issue 7.3 Apr/May on both the 2011 and 2014 code changes. you made reference to Marvin Harmon's comments about service disconnects I would like to read those, do you happen to recall what article they where in.

Thank You David

 

[jaggedben]

I went to Solar Pro Site and read issue 4.3 Apr/May and issue 7.3 Apr/May on both the 2011 and 2014 code changes. you made reference to Marvin Harmon's comments about service disconnects I would like to read those, do you happen to recall what article they where in.

Thank You David

I couldn't find the comments I remembered (they may have been in a forum), but here is an entire article by him which is obviously based on the premise that Article 230 applies. Note that he doesn't say that the PV disconnect has to be grouped with the normal service disconnecting means, but it's all based on interpreting 230.

http://solarprofessional.com/articl...um-number-of-disconnects?v=disable_pagination

 

[SolarPro]

This Mike Holt article may be the one you are looking for:

NEC Section 705.12 and Utility Interconnections

 

[david]

I couldn't find the comments I remembered (they may have been in a forum), but here is an entire article by him which is obviously based on the premise that Article 230 applies. Note that he doesn't say that the PV disconnect has to be grouped with the normal service disconnecting means, but it's all based on interpreting 230.

http://solarprofessional.com/articl...um-number-of-disconnects?v=disable_pagination

This Mike Holt article may be the one you are looking for:

NEC Section 705.12 and Utility Interconnections

Thank you for those links,

I think the distinguishing point I keep finding myself coming back to is the AC output is connected through two 30 amp 2-pole back-feed breakers one in the 200 amp panel (exterior @ house)And one at the 100 amp panel interior garage.

If I open the 30 amp 2-pole at the house and open the 30 amp 2-pole at the garage to just shut down both solar arrays I still have utility power through the 100 amp feeder between the two panels.

If that was not the case I think this would bring this installation back into the debate as how to define the 200 amp exterior house panel.

That being said the PV contractor was even angry when I suggested as a compromise to label both the utility service location and the 200 amp panel location identifying source locations. I did receive a voice mail today indicating that he would be willing to add some additional labeling.
There was still a lot of contention in the message he evidently feels that this would be a conflict between article 230 and article 690. I really do not see this as being a conflict.

His assertion is that the disconnect has to be with- in 10 feet of the utility metering, I am aware that the utility specifies a location for an exterior disconnect before they will allow this system to tie to their grid, He will not except that does not have to be the NEC required disconnect for this system

He wants to qualify this system as having one connection point using 690.64 (A)Point of Connection.

I see this as two different panels having two different points of connections through two different solar arrays and 690.64 (B) being applicable to both the house panel and the garage panel

Still reading though !

 

[jaggedben]

Thank you for those links,

I think the distinguishing point I keep finding myself coming back to is the AC output is connected through two 30 amp 2-pole back-feed breakers one in the 200 amp panel (exterior @ house)And one at the 100 amp panel interior garage.

If I open the 30 amp 2-pole at the house and open the 30 amp 2-pole at the garage to just shut down both solar arrays I still have utility power through the 100 amp feeder between the two panels.

If that was not the case I think this would bring this installation back into the debate as how to define the 200 amp exterior house panel.

I think that's a reasonable position.

That being said the PV contractor was even angry when I suggested as a compromise to label both the utility service location and the 200 amp panel location identifying source locations. I did receive a voice mail today indicating that he would be willing to add some additional labeling.

I'd say he should be willing. While it costs money to have custom signage made, it's certainly less than changing any aspect of the installation.

There was still a lot of contention in the message he evidently feels that this would be a conflict between article 230 and article 690. I really do not see this as being a conflict.

I agree. He muddied the waters as far as 690.64(A) is concerned by putting that 100A panel in. (And btw, as of 2011 code that is 705.12(A).)

His assertion is that the disconnect has to be with- in 10 feet of the utility metering, I am aware that the utility specifies a location for an exterior disconnect before they will allow this system to tie to their grid, He will not except that does not have to be the NEC required disconnect for this system

If the utility requires the disconnect within 10ft of its meter then that's the only thing requiring it. NEC does not require it, and the meter could go anywhere in the branch circuit. Again, don't see the need for the 100A panel in this respect, it could have been a branch circuit all the way from the new 200A panel to the garage. Any disconnects required at the meter or at the garage could be safety switches.

He wants to qualify this system as having one connection point using 690.64 (A)Point of Connection. I see this as two different panels having two different points of connections through two different solar arrays and 690.64 (B) being applicable to both the house panel and the garage panel

This is a debatable point as to how to designate, say, an AC combiner panel for multiple inverters that is connected on the supply side of the normal service disconnecting means. My opinion has always been that you can have multiple types of connections in series (i.e. a supply side connection for the combiner and then the individual inverter connections are considered load side connections), and that the rules for each connection depend on the type of connection. That's an interpretation though.

But again, if you are installing a new set of service conductors for PV - which you are allowed to do under 230.40 Exception 5 - then that set of service conductors should only be used for PV or other systems that fit under 230.82(5) and (6). As I keep saying, the 100A panel at the garage doesn't follow the spirit of the code. It is not necessary for the PV and I think the customer must be intending to add loads to it or else it was an expensive mistake for the PV contractor to install it.

I think it's very reasonable of you to simply require him to add labeling so that anyone working on the house knows the configuration. The system is not unsafe for normal operation but could be very confusing for first responders or anyone else who wants to shut the premises power down.

 

[david]

I emailed the PV contractor the solar pro magazines two articles from the 2011 and 2014 code change as a point of reference and followed that up with a phone call letting him know I am responding to his request to send out a written explanation of any violations and corrections needed at the site.

He said I was simply searching the code looking for anything I could point to as a violation. I try to explain to him that we are not current with the 2011 nor the 2014 and I just wanted a reference point to any code changes that he wanted consideration for.

When I was on site with this contractor I made mention of everything being installed in PVC conduit I reminded him that he kept insisting that the installation is totally compliant with current codes. His response is to get angry each time I try and address our concern. He said he never said that the PVC met code, his position is the only PVC he addressed in our last conversation on site was the PVC on the exterior of the buildings.
He insist that the PVC is safe, and he said besides as soon as I enter the building I have a DC disconnect.
Though true he goes to a DC disconnect in short order for the house, But the garage goes at least 15 ft. before the DC disconnect in the garage

 

[SolarPro]

I'm going to quote the 2011 NEC, just because that's what's on my desk [italics added]:

690.31(E) Direct-Current Photovoltaic Source and Output Circuits Inside a Building.
Where dc photovoltaic source or output circuits from a building-integrated or other photovoltaic system are run inside a building or structure, they shall be contained in metal raceways, Type MC metal-clad cable that complies with 250.118(10), or metal enclosures from the point of penetration of the surface of the building or structure to the first readily accessible disconnecting means.

These requirements are also found in NEC 2008. It starting to sound to me like the contractor is touchy because his grasp of the Code requirements is wanting. If he can't get something this simple right, it makes one wonder what other liberties he is taking with the Code.

 

[ggunn]

I emailed the PV contractor the solar pro magazines two articles from the 2011 and 2014 code change as a point of reference and followed that up with a phone call letting him know I am responding to his request to send out a written explanation of any violations and corrections needed at the site.

He said I was simply searching the code looking for anything I could point to as a violation. I try to explain to him that we are not current with the 2011 nor the 2014 and I just wanted a reference point to any code changes that he wanted consideration for.

When I was on site with this contractor I made mention of everything being installed in PVC conduit I reminded him that he kept insisting that the installation is totally compliant with current codes. His response is to get angry each time I try and address our concern.

Hang a red tag and walk away.

 

[david]

As a result of the visual electrical inspection conducted at ##########. Our concerns listed in the attached document need your attention.

Feel free to contact me to discuss any of the items listed if needed.


At the premise located at ######## consist of a main building and a secondary garage. The subject of this letter is corrections needed to the PV system consisting of roof mounted solar arrays and associated equipment installed at both the main building and the secondary garage.

The following corrections are needed to obtain compliance with NFPA 70 2008. (The Fine print note included is an informational note only and is being included to provide clarification for the requirement found in 250.58
1. Identification in the form of a directory plague at both the utility supply( ?utility Service Disconnect?) and the solar supply (solar ?service disconnect?)as required by section 225.37,230.3,690.56 & 705.10
2. Bonding together the existing utility service grounding electrodes and the newly installed solar system electrodes to limit potential differences between the two associated wiring systems as indicated in the fine print note following the requirement found in 250.58
(FPN Bonding together of all separate grounding electrodes will limit potential differences between them and between their associated wiring systems.)
3. At the main building roof top array, an additional grounding electrode conductor connected directly to the array frame(s) or structure and bonded to the main buildings grounding electrode system. ( note: refer to correction item #2) 690.47 (D)
4. At the secondary garage building roof top array, an additional grounding electrode conductor connected directly to the array frame(s) or structure and bonded to the garage buildings grounding electrode system. 690.47 (D)
5. Removal of the PVC interior conduit wiring method at both the main building and the secondary garage building Direct-Current Photovoltaic Source and Output Circuits Inside a Buildings and install using metal wiring methods from the point of penetration of the surface of the building or structure to the first DC rated disconnecting means 690.31(E)

225.37 Identification.
230.2 (E) Identification
690.56 (B) Identification of Power Sources.
705.10 Directory.
250.58 Common Grounding Electrode.
690.47 (D)Additional Grounding Electrode System.
690.31 IV. Wiring Methods, Methods Permitted.

225.37 Identification. Where a building or structure has any combination of feeders, branch circuits, or services passing through it or supplying it, a permanent plaque or directory shall be installed at each feeder and branch-circuit disconnect location denoting all other services, feeders, or branch circuits supplying that building or structure or passing through that building or structure and the area served by each.
230.2 Number of Services. (E) Identification. Where a building or structure is supplied by more than one service, or any combination of branch circuits, feeders, and services, a permanent plaque or directory shall be installed at each service disconnect location denoting all other services, feeders, and branch circuits supplying that building or structure and the area served by each. See 225.37.
690.56 Identification of Power Sources. (B) Facilities with Utility Services and PV Systems. Buildings or structures with both utility service and a photovoltaic system shall have a permanent plaque or directory providing the location of the service disconnecting means and the photovoltaic system disconnecting means if not located at the same location.
705.10 Directory. A permanent plaque or directory, denoting all electric power sources on or in the premises, shall be installed at each service equipment location and at locations of all electric power production sources capable of being interconnected.
250.58 Common Grounding Electrode.
Where an ac system is connected to a grounding electrode in or at a building or structure, the same electrode shall be used to ground conductor enclosures and equipment in or on that building or structure. Where separate services, feeders, or branch circuits supply a building and are required to be connected to a grounding electrode(s), the same grounding electrode(s) shall be used.
Two or more grounding electrodes that are bonded together shall be considered as a single grounding electrode system in this sense.
690.47 Grounding Electrode System. (D) Additional Electrodes for Array Grounding.
Grounding electrodes shall be installed in accordance with 250.52 at the location of all ground- and pole-mounted photovoltaic arrays and as close as practicable to the location of roof-mounted photovoltaic arrays. The electrodes shall be connected directly to the array frame(s) or structure. The dc grounding electrode conductor shall be sized according to 250.166. Additional electrodes are not permitted to be used as a substitute for equipment bonding or equipment grounding conductor requirements.
The structure of a ground- or pole-mounted photovoltaic array shall be permitted to be considered a grounding electrode if it meets the requirements of 250.52. Roof-mounted photovoltaic arrays shall be permitted to use the metal frame of a building or structure if the requirements of 250.52(A)(2) are met.

690.31(E) Direct-Current Photovoltaic Source and Output Circuits Inside a Building. Direct-Current Photovoltaic Source and Output Circuits Inside a Building. Where direct-current photovoltaic source or output circuits of a utility-interactive inverter from a building-integrated or other photovoltaic system are run inside a building or structure, they shall be contained in metal raceways, or metal enclosures, from the point of penetration of the surface of the building or structure to the first readily accessible disconnecting means. The disconnecting means shall comply with 690.14(A) through (D).


Sincerely
Electrical Code official
David

Solar PV Contractors Response
David,

1: We will provide a placard indicating that the location of the ?pre-existing? building service is located in the basement opposite the wall where the solar disconnect is located. See attached. We can put either of these up, let me know which one. We do not agree with your assessment but as I told you on the day of inspection, we will make the change in the interest of expediting the process, you just have to tell us what you want.
? 690.56 says this is only necessary when the added solar disconnect is not located next to the meter which in this case it is. There is a single disconnect located within 10 ft and visual site of the service meter as required by the PUC. This single disconnect terminates ALL solar AC circuits with a single fused disconnect.
o 690.3 says that 690 supersedes conflicts in other parts of the code.

2, 3 & 4 are already installed and to code. Please specify what is out of code with these three points ASAP. We cannot fix what we do not know is broke. We cannot commit a crew to the field until we know exactly what we need to do at the site. As I explained and showed you on site, the panels are bonded to the rail via a WEEB, the rails are bonded to each other and the ground for the system, the entire system is bonded to new ground electrodes located at both the main house and the garage. Both new ground electrodes are tied together and tied to the existing house ground. All grounding conductors are either continuous, bonded at a grounding bar or utilize a rated bonding method.

5 We agree with this and will correct. Had you pointed this out when you first inspected we would have corrected it immediately. My crew was confused about occupancy type and thought it was acceptable in a garage. This has now been corrected in our internal processes.


Thanks,
##############

 

[david]

We really do not want auxiliary electrodes as called out in 2014, We are under 2008, We feel we have the right to require the additional grounding electrode conductor either be bonded to the building grounding electrode system or if an additional electrode is installed that electrode be bonded to the buildings grounding electrode system.

I believe the PV contractor is referring to the equipment grounding system and is not understanding the requirement for the additional electrode that is required in 2008 not referenced in the 2011 and brought back in with some changes in 2014

The PV contractor no matter how many times I tell him the solar disconnect is in relationship to the utility service disconnect, not the solar disconnect in relationship to the Utility Meter.

The PV contractors understanding of a conflict is if a requirement is not specifically addressed in article 690 than he can ignore other sections of the code and he defines that as a conflict.

 

[ggunn]

We really do not want auxiliary electrodes as called out in 2014, We are under 2008, We feel we have the right to require the additional grounding electrode conductor either be bonded to the building grounding electrode system or if an additional electrode is installed that electrode be bonded to the buildings grounding electrode system.

I believe the PV contractor is referring to the equipment grounding system and is not understanding the requirement for the additional electrode that is required in 2008 not referenced in the 2011 and brought back in with some changes in 2014

The PV contractor no matter how many times I tell him the solar disconnect is in relationship to the utility service disconnect, not the solar disconnect in relationship to the Utility Meter.

The PV contractors understanding of a conflict is if a requirement is not specifically addressed in article 690 than he can ignore other sections of the code and he defines that as a conflict.

At least he had the snap to keep his communication civil when he was on the record.