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Old 11-02-19, 08:49 PM   #12
DIY Geek
Join Date: Apr 2013
Location: Sunny Florida
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Codes have a purpose in life, it's to keep your neighbor from torching their house because they DON'T know enough about electricity to make sound decisions.

A three line diagram is literally what it sounds like: (If you can read and write schematics, you can write a 3-line diagram. Based on your holiday light show, I think you can probably handle this). L1, L2, Neutral, and Ground each are shown as a line from the furthest micro-inverter all the way to the main electrical panel that the PV system will connect to. Every stop or connection you make along the way is detailed out with the make & model of the thing.

In my case, I showed the PV panels (listing their manufacturer, model number, wattage). Then I showed the + and - wires that connect to the micro-inverter. I showed the micro-inverter as a smaller rectangle with the Enphase, M215-60-2LL-S22 designations. At that point, I start showing 4 wires and wire gauges (L1, L2, N, Gnd). When I go through a connection point or junction box, I list out the manufacturer and model of the box. If I hit a circuit breaker, I list out the current rating for the breaker, and whether it is single pole or a double pole breaker (they're double pole). Also show the "wiley" WEEB washers that ground the panel frames to the roof rack. Each segment of roof rack needs a jumper to connect the rack electrically to the next piece of adjacent racking. Show the continuous bare ground wire that grounds each piece of the rack to your ground rods (that wire being continuous without breaks is SUPER important). Make sure you show two 8' ground rods spaced at least 8 feet apart. Your existing home electrical system may currently only utilize a single ground rod, now is your chance to upgrade to TWO ground rods since the latest NEC code requires two rods. In my three line diagram, I also listed voltage drops expected based on the maximum potential current being generated by the system and the length of the wire to the next thing. I drew it all on 11x17 paper in Autocad, because I draw in Autocad everyday as my main means of sustainable employment.

Above was just the "electrical" diagram, and since you're in Florida, you have to submit that 3-line diagram to FSEC in Cocoa Beach along with a check for $250 or whatever the latest design review fee now is. FSEC will review the three line diagram for NEC compliance, since the FL legislature doesn't seem to think each individual municipality has the thorough understanding of the NEC necessary to review PV systems and determine whether they are NEC compliant. (honestly, I'd rather converse with one person who does nothing but review PV system designs, then deal with explaining a PV system to a "Noob" at the local municipality.) When I submitted my first design, they responded with a phone call to suggest a minor design modification, and blessed my design when I incorporated their "hint". When FSEC gives you your certification number, you need that to carry to your local municipality or county (which ever has jurisdiction) and apply for your building permit. If you can get your hands on a copy of the latest NEC code book, it helps to understand what types of cables can be used where, and what things in a PV system need grounding. It's also a bit confusing reading the NEC, so review Mike Holt's PV grounding information online. I think I found slides from some seminars he had done in the past that were helpful. The whole section on PV systems in the NEC is good to understand so you know where to backfeed the energy into your main panel, and can have an intelligent conversation if anyone questions anything as you are installing your system.

Thanks to Hurricane Andrew, and numerous storms since, most FL municipalities will want some form of stamped structural engineering design that says the PV array won't rip the roof off in the event of a storm, or go flying through the neighborhood (if it's not attached to the roof). This is where you have to go out and employ a professional. In my case, I know someone who is a structural engineer (P.E.) who has a personal business in addition to being employed as a structural engineer. He's helped me with structural engineering upgrades to my house built in 1961. He did the math to determine that a 3 second gust of 170MPH would not rip the 4.4kW PV array off my roof, if I used 102 attachment points to the roof trusses. I still hope we never test that math, but that math and the liability associated with his math is worth $$ to a structural engineer. I paid him for his knowledge and the license he keeps with the state of FL. Having my own professional licenses to upkeep, and having taken college classes to get my own professional licenses, I don't hassle him about his "rates" when I need his expertise. The state deems me unfit to do the higher math necessary to determine wind load calculations, just as it deems him unfit to do what I hold licenses to do.

With those two documents described above, the FL PV Certification Number, and the PE structural design drawings, I was able to visit my local municipality and apply for a permit to install my own PV system.

When the inspectors came out for the "in-progress" and "final" inspections, they reviewed my permit documents (the 3-line diagram, I drew, and the structural engineer's drawings). They asked me where I was at in the install process, asked me to show them where this was or that was. They reviewed my install for obvious errors like bolts that didn't hit the rafters in the attic, electrical connections which were not NEC compliant or connectors that were not torqued to spec. With all that, at the end of my final inspection, the inspectors were impressed that I didn't cut any corners, or miss any
inspection points, considering I don't do this for a living. I think it's the fact that I "dont' do this for a living" that keeps me from overlooking things trained pros who do this every day may overlook. I treated the NEC like a textbook, learning what I could reading it, and asking questions when it seemed confusing. In my case, my municipality will take questions during two periods each day. When it came to labeling the panels, I went to my municipality and asked precisely which labels they wanted on which panels, because the NEC simply said "electrical panels energized by PV must be labeled appropriately" or some other generic language. I said "here's the decals I found online for PV panels, which decals do you want where?" and the staff were helpful in picking what they wanted to see on which electrical panel as well as explaining why. When the inspectors (one for electrical, one for structural) came out for the final inspection day, the panels had their warning labels and I was able to explain why each panel was labeled with a specific decal.

You are correct, I'm NOT in the panhandle. I moved back south when I finished my studies at UF, because it got below freezing in Gainesville. You can tell the seasons change when the license plates change color down here, that's about it. I know some good folks who live in the panhandle, but I am a native from SoFL.
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