<html><head></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; ">I've also seen failures/ nuisance tripping due to loose connections at the breaker. The heat then wreaks havoc on the breaker internals.<div><br><div>
<span class="Apple-style-span" style="border-collapse: separate; border-spacing: 0px 0px; color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; text-align: auto; -khtml-text-decorations-in-effect: none; text-indent: 0px; -apple-text-size-adjust: auto; text-transform: none; orphans: 2; white-space: normal; widows: 2; word-spacing: 0px; "><div>R. Walters</div><div><a href="mailto:ray@solarray.com">ray@solarray.com</a></div><div>Solar Engineer</div><div><br class="khtml-block-placeholder"></div><div><br class="khtml-block-placeholder"></div><br class="Apple-interchange-newline"></span>
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<br><div><div>On May 17, 2010, at 8:23 AM, jay peltz wrote:</div><br class="Apple-interchange-newline"><blockquote type="cite"><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; ">HI Drake<div><br></div><div>I don't know if this could apply to your situation, but I've seen the QO/QOU fail from debris getting into the breaker itself.</div><div>Around here there are insects that deposit mud into small openings, like on those breakers.</div><div>I've seen this cause the breakers to fail.</div><div><br></div><div>jay</div><div><br></div><div>peltz power<br><div><div>On May 17, 2010, at 7:02 AM, Drake Chamberlin wrote:</div><br class="Apple-interchange-newline"><blockquote type="cite"><div>
The QO breaker I saw fail was a disconnect switch for an Air 303.
The run from the battery bank was substantial, and the wire was number
10. At the time, I calculated the amperage available (I
-V/R) and the short circuit current available was not close
to the 5000 amp AIC of the breaker for its DC rating.<br><br>
At 06:13 PM 5/16/2010, you wrote:<br>
<blockquote type="cite" class="cite" cite="">Voltage is not the issue here,
it is current, and battery fault currents can be staggering - far more
than one would ever encounter in a typical AC system fed from a
distribution transformer. I have seen a 200A Class T fail to act on
an 48V inverter fault which resulted in welding the metal tabs of the
fuse holder (which had been greased with copper-laden Penetrox E) to
their sockets. That indicates a fault current well north of 200,000
amps, quite possibly sseveral times that. A fire ensued,
which triggered the gas protection system and fortunately resulted in
almost no peripheral damage. It did cost about $10k to recharge and
recertify the Inergen system. The inverter manufacturer was quite
cagey on warranty replacement until they saw the photos - at which point
a replacement miraculously arrived by overnight air.<br><br>
<br><br>
On May 15, 2010, at 9:43 , Drake Chamberlin wrote:<br><br>
<blockquote type="cite" class="cite" cite="">I did see a QO breaker fail to
trip on a 24 volt DC system with only battery voltage behind it. It
burned a #12 wire completely in two. <br><br>
<br>
<blockquote type="cite" class="cite" cite="">The 48v is a max rating not a
nominal rating.<br>
So yes only good for 12 and 24v systems.<br><br>
However with CBI breakers I don't understand why the need for QO for DC
anymore?<br><br>
jay<br><br>
peltz power<br>
On May 15, 2010, at 6:28 AM, Rebekah Hren wrote:</blockquote><br>
<font color="#0000FF">Drake Chamberlin<br>
Athens Electric<br>
OH License 44810<br>
CO License 3773<br>
NABCEP </font><font size="1" color="#0000FF">TM
</font><font color="#0000FF">Certified PV Installer <br>
Office - 740-448-7328<br>
Mobile - 740-856-9648 </font></blockquote><br>
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