[RE-wrenches] backfeeding "six disconnect" panel

Mon Nov 1 21:12:47 PDT 2010

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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