Dana, I'll echo Scott's earlier comment: connecting to an empty 'main' breaker position that is on the top bus will be a supply-side connection. From Code Corner #126: * * *Some dwellings have main-lug-only panels. There is no * *single main breaker feeding the panel, but up to six main * *breakers are allowed. Empty breaker positions can be used * *as supply-side connections. The basic restriction (which * *will be in the 2011 NEC) that would apply to this type * *of main service panel is that the sum of the overcurrent * *devices from the PV inverter(s) should not exceed the * *rating of the panel bus bar or the rating of the service * *entrance cables.*
-Phil Boutelle Real Goods Solar On Mon, Nov 1, 2010 at 6:55 PM, Dana Brandt <[email protected]> wrote: > Hi everyone, > > I just noticed my last email didn't go through because I'd attached > pictures of the panel. If you're interested in the pics of the panel please > contact me off-list. > > Thanks for the feedback. To clarify, the upper part of the bus is lug-fed > directly from the service meter - no overcurrent protection. I have this > same situation in two homes - one has a Bryant panel, not sure about the > other. > > It seems possible connecting to the top bus could be considered a supply > side connection. It's done through a panel bus, though, which seems like > maybe it wouldn't qualify. > > It's true that the 60A breaker feeding the 100A bus fulfills the > calculation requirements. However, the calculation has to follow upstream to > the bus supplying that 60A breaker, so again we have a potential problem > since there's no overcurrent protection for that bus. > > So, it seems the real question is about that top bus. Can we consider a > connection there a supply side tap? If not, who do we do the 690.64 (B) (2) > calculation without a main breaker? > > Thanks! > > Dana > > Dana Brandt > Ecotech Energy Systems, LLC > www.ecotechenergy.com > [email protected] > 360.510.0433 > > > On Thu, Oct 28, 2010 at 6:37 PM, Matt Lafferty <[email protected]>wrote: > >> Hi Dana, >> >> "Sounds like" you have a lower-bus rated at 100A being fed by a 60A >> breaker... Yes? >> >> If so, technically speaking but not necessarily the right thing to do, you >> have a SWEET SETUP! In 690.64 terms, you are legally allowed 120A to feed >> that bus. Which converts to a maximum 60A PV interconnection breaker located >> at the opposite end of the bus from the 60A supply breaker. This is a panel >> configuration that I have wished was still made for many years. >> >> The downside is... It's probably older than me. With really wimpy buses. >> And really bad options for replacement breakers. And is full of 2-wire >> homerun circuits. >> >> If it doesn't have a perfect-in-every-way bus, it's time for a new panel. >> You also need to be able to buy real... Modern.... And New UL Listed >> breakers. Those gray looking replacement breakers in the home improvement >> store? They're NOT OK. In any way. >> >> Wadsworth? FPE? Bulldog? &...??? These panels are NOT OK for >> interconnection at this point. Time to upgrade. Yes, really. Zinsco? >> Depends. Any panel with signs of arcing around the bus anywhere? Better have >> a damned good explanation before I'd be tying in some PV. I know of a >> couple. Warped breakers? Change it! >> >> I just got done doing a 90% rewire on a friend's house and it tore my >> heart out sending the panel to the recycler.* (This friend is into >> long-term thinking and sustainable everything. I would have left it if I >> could and so would they.) *The bus was pristine. It is rumored that Al >> Capone used to stay in this place when he was in the area. The panel was >> giant, with lots of room. This panel had a coolness factor off the >> charts. But... I couldn't reliably get trustworthy breakers. And it was >> my friend's house. Somebody I care about. I couldn't leave it in there. I >> use the same judgement whether my customer is a friend or not. >> >> If what you have is a modern panel, share! I know I would personally >> appreciate it if you were able to share mfr, model, pictures, etc. Whenever >> we are upgrading/swapping/moving a service panel, we need to be installing >> something that provides the best opportunity for interconnection of >> distributed resources. We don't have those at this point. And we need them. >> A split-distribution *(not just split-bus)* service panel is one way to >> accomplish this. The trick is to limit the possible size of the breaker >> feeding the "2nd" bus *(the lower bus in this case).* It's not rocket >> science. >> >> I'd be happy to use and publicize a product that a mainstream manufacturer >> came up with to deal with this. How about you? >> >> $0.02001, >> >> Solar Janitor >> >> PS - Home rewiring for friends only. I love doing it, but I do it for >> love. There ain't no amount of money that makes me want to do it just for >> money! >> ------------------------------ >> *From:* [email protected] [mailto: >> [email protected]] *On Behalf Of *Dana Brandt >> *Sent:* Thursday, October 28, 2010 5:19 PM >> *To:* RE-wrenches >> *Subject:* [RE-wrenches] backfeeding "six disconnect" panel >> >> Hi everyone, >> >> I'm working on two systems for homes that have the old style breaker >> panels with no single main breaker. Instead, they have six breakers in the >> upper part of the panel each labeled "main breaker," which satisfies the six >> disconnect rule. The bus bar is split, with one of the six upper breakers >> (60A) feeding a separate bus in the lower half of the panel. It appears that >> the upper bus is rated for 200A, and the lower at 100A. The sum of the main >> breakers does not exceed the 200A rating of the upper bus. There are spare >> breaker slots on both the top and bottom buses. How do I deal with 690.64 >> (B) (2) when there's no main breaker? >> >> Thanks! >> >> Dana >> >> Dana Brandt >> Ecotech Energy Systems, LLC >> www.ecotechenergy.com >> [email protected] >> 360.510.0433 >> >> _______________________________________________ >> List sponsored by Home Power magazine >> >> List Address: [email protected] >> >> Options & settings: >> http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org >> >> List-Archive: >> http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org >> >> List rules & etiquette: >> www.re-wrenches.org/etiquette.htm >> >> Check out participant bios: >> www.members.re-wrenches.org >> >> >> > > _______________________________________________ > List sponsored by Home Power magazine > > List Address: [email protected] > > Options & settings: > http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org > > List-Archive: > http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org > > List rules & etiquette: > www.re-wrenches.org/etiquette.htm > > Check out participant bios: > www.members.re-wrenches.org > > >
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