What the inspectors looked for

Roderick

My DIY grid-tied PV system just passed City inspection last week, and Utility inspection a couple days later. However, it did NOT pass on the first try. Here are some observations for the benefit of forum readers. (This is for San Jose, California.) I'd also be interested in what, if anything, inspectors flagged for other readers.

HOSES NOT STRAPPED DOWN. I had one 3' length of flexible nonmetallic conduit just sticking out. Yup, I should have secured it. Interestingly, I was also supposed to secure the short lengths of the same thing, for instance, between the DC disconnect and the inverter. This was perhaps and 18" length of hose, and rigidly anchored at the fittings at each end. Ok, I put straps on those, too, maybe 6" away from the end points. This was enough to pass.

NO WARNING LABEL ON CIRCUIT BREAKER PANEL. I was told by the City that the Utility would require this, and pasted directly onto the outside of the circuit breaker panel. My plans were to put the "Directory of power generation sources" on a plaque 2 feet to the left of the breaker panel. I put on a label, and it passed City. When the Utility came by to inspect, their Meter Tech put on their own label warning of generator sources, which said about the same thing. Maybe the City inspector had seen the Utility stickers, and assumed they were provided by the installer. Whatever, it wouldn't hurt to put such a sticker on your installation. My text was something like, "Directory of power sources feeding this panel - 1. Photovoltaic System (disconnect switch to your left) 2. Regular PG&E Electric Service"

AC DISCONNECT WIRED WRONG WAY. The City inspector wanted to see the Inverter connected to the top (line) side of the switch, with the rationale that it was custom for the power to flow from top to bottom. However, I had wired it up the other way, with the mindset that when the switch is open, it is customary to think of the bottom (load) side terminals as being de-energized. I found support for my position later in a John Wiles article on the internet. As soon as the return inspector saw the name "John Wiles," he rescinded the complaint.

SOLAR MODULE INTERCONNECT CABLES NOT SECURED. On the roof, the inspector wanted to see the MC cables going from module to module tie-wrapped to the racks. I had walking space between separate sections of my array, and the cables were laying loose on the roof deck. I'm not sure of the reasoning behind securing the cables. The first inspector implied that it was so that someone wouldn't trip over the cables, which would suggest that the cables are best flat against the roof. The second inpsector thought it was to keep the cables from degrading on the hot roof surface, suggesting that it would be better to have the cables a few inches off the roof. I took up the slack and secured with large tie-wraps. It didn't take long. I chose to leave the inter-module portion of the cables lying flat on the roof, and it passed.

THWN INSTEAD OF THWN-2 USED FROM ARRAY TO DISCONNECT. The kit that I bought included some type TC wire, rated THWN/THHN. The inspector was unfamiliar with the wire, and had to check whether it was OK to put it in conduit (2 conductor TC cable looks like Romex, which is no good in conduit). The NEC said it was ok. But the inspector immediately flagged the THWN rating (this seems to be a shortcut check, THWN-2 would not have raised a flag, but for other ratings, they want to see the calculations). I showed my work, and we discovered that the wire was rated for 90 C at dry/damp, but only for 75 C at wet. And conduit is considered wet, because water tends to collect in it. When wet, the cable would have supported 11.7 amps with safety factors and deratings built in for hot sun. The short circuit current of my panels was about 14A. I discovered that if you go to Home Depot, Lowe's, etc., that you can't find #10 building wire in THWN-2 - it's always plain THWN. But #8 gauge wire always seems to be marked THWN-2. I don't know why this is, and it looks like the same insulation to me. Ironically, the thicker #8 wire was more flexible than the #10, because it came standard with 19 strands instead of 7. I pulled the new wire through the conduit, and had a 2' sample left over to show to the inspector.

As a note, the inspector said that all disconnect switches are supposed to be at least 3' from any natural gas vents, which could be a problem if your gas service come in at the same place as electrical. However, he said they often let it go if it's an outdoor, well-ventilated location.

Another observation is that the City inspectors had John Wiles's articles in their briefcases, and may have been working off a checklist developed by the same. Clearly, the man is highly revered in the Inspection community.

I FAXed the City sign-off to the Electric Utility (PG&E), and the next day, I got an email saying that a Meter Technician would come out to inspect the system and install a new meter. The day after that, we were surprised to see a new meter already installed, and the PG&E inspection tag. I suspect they don't check very much, and count on the City to enforce safety issues.

On the back of the inspection tag were some check boxes for common reasons for failure, something to keep in mind. They involved the AC disconnect not being within 10 feet of the meter, or not within sight, or not having access to the meter or disconnect.

arcandspark

Re: What the inspectors looked for

This is great stuff, thanks for sharing it with everyone, it really helps. I had issues with electrical inspectors in my town here in north Texas. Since the inspector had never seen a solar installation with an inverter and batteries as large as a small car, he must have thought it was some kind of mini nuke power system, his eyes were as big as cup saucers, and he kept scratching his head. What I did was to make a booklet, in it was a picture of every section AC DC PV, junction boxes, connections, breaker boxes, any and everything was pictured inside with a note telling what section of the NEC code book it followed and why. I also figured that he would have to flag me on a couple things to justify his job so I left a couple warning lables off and had a couple wrong sized wire nuts just so he could pop me and make it look like he was doing his job. He felt good about finding these items I had left for him and loved the booklet which was more of a teaching tool for him. I gave him the booklet on the second inspection after correcting the small items used to keep him amused. It worked out great. One item I had to fight for was a wind generator. In my city the wind generator is not allowed but I got around that by making it portable and buiilding it on a trailer you can tow behind your car. So even though I can not have one attached to the house or a fix installation on my property, the portable one is completely leagal. When the windy months come around I set it up in my back driveway and plug it in, and the neighbors and city cant touch me. I plan on moving out of the city and building an off grid system some time next year. I am currently helping my friend build a 3000 sq ft home off grid. We are using solar, wind, and co-generation for power and DHW. Again thanks for the great input on your DIY install. arcandspark

niel

Re: What the inspectors looked for

both of you guys are giving great input. heck it never occured to me to leave a few stupid things for them to find and make them feel good they found something.

Roderick

Re: What the inspectors looked for

niel wrote:

... heck it never occured to me to leave a few stupid things for them to find and make them feel good they found something.

Um, right, that's it - I meant to do that... 

I'm not sure if this is a California vs. Texas thing, but my impression was that the inspector wasn't of the mindset that he MUST flag something.  Our inspectors are overworked (local politics), so I would think they wouldn't want to generate extra visits for themselves unnecessarily.

If anything, when the inspector saw my first hose just swinging in the breeze, he got the impression that I didn't know what I was doing (not far from the truth), and started looking more carefully.  We'll never know, but I think that were it not for the two major issues of loose hose and insulation rating, he might have just told me informally to fix the other items and signed off.

To ArcAndSpark, did you make up your booklet in electronic format?  If so, would you consider making it available as a resource to others with similar aspirations?  Sounds like a tremendously valuable document!

BB.

Re: What the inspectors looked for

On my remodel/solar installation, the inspectors simply reviewed the installation and signed if off. No fuss, no muss--Later I found an electrician had done a "must have been on cocaine" job under my home that the inspectors never even glanced at.

At least out here, the best way to use the inspector is to keep your contractor honest--point out questions that you may have and areas where the inspector may not have looked. They are (or at least, should be) on the property owners side (but don't get me going on city planning commissions--a whole other kettle of fish).

-Bill

mike95490

Re: What the inspectors looked for

Just had my system go on line (see website) and the inspector had never climbed a tall ladder, and would not get onto the roof. I also just discovered, in my breaker panel, the interior cover over the breakers won't fit, and is loose. The bushing they ran the inverter feed wires into, blocks the interior latch. Numbskull installer & inspector for not catching it. And me too, for not seeing it till now. Mike