<div dir="ltr"><div class="gmail_default" style="font-family:arial,helvetica,sans-serif"></div><div dir="ltr"><div class="gmail_default" style="font-family:arial,helvetica,sans-serif">Are they maybe talking about 690.31 that states that circuits over 30V in readily accessible locations need to be guarded? I can't tell if the conductors from the modules to the inverter are in a raceway from your picture. If so, the guarding requirements they are referring to may be 110.27(A)(4)(b).</div><div class="gmail_default" style="font-family:arial,helvetica,sans-serif"><br></div><div class="gmail_default" style="font-family:arial,helvetica,sans-serif">However, I think 110.27(B) would be more important in a carport situation, in which case your suggestion to place inverters as high as practical seems like the prudent option. On the other hand, the Guarding of Live Parts section is for the protection of persons specifically. Common sense would dictate that you want inverters out of the reach of typical vehicles that would use the parking facility or have them adequately protected. I see the desire to get them up as high as possible.</div><div class="gmail_default" style="font-family:arial,helvetica,sans-serif"><br></div><div class="gmail_default" style="font-family:arial,helvetica,sans-serif">Ultimately, if they are going to be placed up high and require portable ladders or lifts for service, what's the difference between 8 feet and 16 feet? It's not much harder to install or service at the higher height.</div><div class="gmail_default" style="font-family:arial,helvetica,sans-serif"><br></div><div class="gmail_default" style="font-family:arial,helvetica,sans-serif">On the flip side, cost be damned, I won't specify anything but microinverters or MLPE that isolates module DC output on a carport due to an uncontrolled smoldering fire I was called to help with. The DC combiners were not readily accessible, and even with the fire department's ladder set up for me to help to shut them down, it doesn't stop the DC current from flowing as wires melt together. There are just too many ways DC conductor strings can be damaged in a carport situation. At a minimum, I think there should be a readily accessible DC disconnecting means for each string to compartmentalize shorted conductors to the extent possible, and the quantity of DC conductors bundled together should be minimized. That's just my design theory. I realize that cost is important and DC systems are safe in theory... but why take the risk? I have no problem convincing consumers to spend the extra $ on micros once I tell my story. Plus, the cost difference is much less when warranty is considered. Anyway, another debate for another day. I don't mean to get too far off-topic. My point is that height is not necessarily safer in this case. A readily accessible means of DC disconnect might be a good idea.</div><div class="gmail_default" style="font-family:arial,helvetica,sans-serif"><br></div><div class="gmail_default" style="font-family:arial,helvetica,sans-serif">Jason Szumlanski</div><div class="gmail_default" style="font-family:arial,helvetica,sans-serif"><br></div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Tue, Nov 24, 2020 at 2:48 PM <a href="mailto:petertor@pobox.com">petertor@pobox.com</a> <<a href="mailto:peter.parrish@calsolareng.com">peter.parrish@calsolareng.com</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><u></u>
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I am providing consulting services to a school district in Southern California, and I came up with an issue regarding the placement of inverters.
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These are PV arrays are "solar carports" and the inverters (usually 60 kW-class) are mounted on columns. The advice I have given the School District is to stipulate in the contract with the EPC company that these inverters should be "placed as high as practical" on the columns. Their counter-offer was to cite a section of the NEC 2017 that places a minimum height above grade (parking lot asphalt).
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But they have failed to do so, as of this morning.
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I remember that the NEC code distinguished between secure locations (e.g. switch gear in a closet under lock and key) and locations accessible to the general public.
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<img src="cid:175fbe5d2e2cb971f161" style="max-width: 100%;" alt="" width="445" height="273">
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My case would be the latter. The above photo shows placement lower than "practical" IMHO.
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Any help with a citation in the 12017 NEC <span style="text-decoration:underline">Handbook</span> would be appreciated.
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- Peter
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<p>Peter T. Parrish, Ph.D.<br>President, California Solar Engineering<br>1107 Fair Oaks Blvd Ste. 351<br>South Pasadena, CA 91030<br>(323) 839-6108<br></p>
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