[RE-wrenches] backfeeding "six disconnect" panel

Tue Nov 2 15:11:35 PDT 2010

I've made similar observations as Matt before about adding the seventh handle, but... A supply-side connection is considered a separate service. Each service is allowed six handles. If you take a panel like we're discussing here and add in a backfed breaker to the top section, you have six disconnects for the first service and one new disconnect for the second service. Seven disconnects in one panel, but still Code compliant.

Thoughts?

Scott

On Nov 1, 2010, at 9:12 PM, Matt Lafferty wrote:

> Dana,
>  
> Connection anywhere "above" any of the six service disconnects is considered a supply-side tap.  One problem with connecting there is that your new number of service disconnects would be seven.
>  
> Connecting to the lower 100A bus fed with a 60A "main" is the most code compliant in theory. The 60A is the main for the purposes of your installation. The other side of the main is the utility. Whether the upper section has an amperage rating or not is moot.
>  
> You still have to make a determination of suitability with regard to breakers, age, condition, etc.
>  
> Cheers,
>  
> Matt Lafferty 
> From: re-wrenches-bounces at lists.re-wrenches.org [mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of Dana Brandt
> Sent: Monday, November 01, 2010 6:55 PM
> To: RE-wrenches
> Subject: Re: [RE-wrenches] backfeeding "six disconnect" panel
> 
> 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
> dana at ecotechenergy.com
> 360.510.0433
> 
> 
> On Thu, Oct 28, 2010 at 6:37 PM, Matt Lafferty <gilligan06 at gmail.com> 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: re-wrenches-bounces at lists.re-wrenches.org [mailto:re-wrenches-bounces at lists.re-wrenches.org] 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
> dana at ecotechenergy.com
> 360.510.0433
> 
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