Sq D as combiner box [RE-wrenches]

[jberdner at sma-america.com]

David:

Yes, Square D QO's and Qou's are dc rated but the 48 Vdc voltage rating only
makes them suitable for use in 12 and 24 Vdc systems.  You need to double
check for a dc rating on the load center - not all are dc rated.
The QO's have a low AIC rating and I have seen them weld closed when trying
to interrupt large fault currents.
In battery based systems I think the Class T or RK5 fuses in series with the
battery is better since it provides current limiting.
The Heinemann breakers are convenient but fuses provide better protection.
This is why I still prefer the old fused Pull Outs in the APT Power centers
to the 250 Amp breakers in the Trace DC 250.

Best Regards,

John Berdner


-----Original Message-----
From: David Palumbo, Independent Power & Light [mailto:ipl at sover.net]
Sent: Wednesday, April 04, 2001 7:14 AM
To: Wrenches
Subject: Sq D as combiner box [RE-wrenches]


Are Square D breakers considered suitable for series fusing pv array?
If so, why not use a rain proof Square D load center as the array combiner
box?
You would still have a Heinemann breaker, or RK5 fuse, or Class T fuse in
your DC disconnect box for catastrophic protection.
Square D breakers are available in 10 amp single pole and that would be an
appropriate size for many modules.

Recent quote from CED QO612L100RB $49.68, QO816L100RB $ 62.88, QO12L125RB $
96.05; single pole breakers run about $ 7.75 for 10 amp.

Dave Palumbo

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