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.
On May 15, 2010, at 9:43 , Drake Chamberlin wrote: > 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. > > >> The 48v is a max rating not a nominal rating. >> So yes only good for 12 and 24v systems. >> >> However with CBI breakers I don't understand why the need for QO for DC >> anymore? >> >> jay >> >> peltz power >> On May 15, 2010, at 6:28 AM, Rebekah Hren wrote: > Drake Chamberlin > Athens Electric > OH License 44810 > CO License 3773 > NABCEP TM Certified PV Installer > Office - 740-448-7328 > Mobile - 740-856-9648 >
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