Ground faults / NEC changes for 2005 [RE-wrenches]

[Steve Willey, Backwoods Solar]

To have battery-source overcurrent in a negative line, the current must come
through a complete circuit involving battery positive source.  Interrupting
it in either neg or pos from the source will stop the current.

IF the boost control passes battery current through from battery + terminal
to PV plus terminal, and IF there is a short between + and - in the array
wiring, battery over current will flow through both + and - in the control,
as evidenced in the pictures.  No breaker in negative circuits would not be
a factor, because if the positive breakers on either side of the control
opened, the loop is interrupted.

You stated that all those breakers were manually off and still arcing was
possible on the board when a screwdriver was applied to it.  this suggests
an additional source of + battery or +PV was available to the board.  Were
there a temp sensor or the external battery current shunt connected to the
board that could have come in contact with + battery voltage?  Any other
wires?  (I would expect a larger wire, and not the temp sensor, would be
required to bringing that much current)
Steve Willey       steve at backwoodssolar.com
www.backwoodssolar.com
Backwoods Solar Electric Systems

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