robbob2112
Doing more research, mosty harmless
I just ran the calculation for 10awg PV wire 100ft long with 140vdc and 25amps - shorted at the midpoint - seems reasonable to me..... it takes 0.96 second for the jacket to melt. Assuming the breaker blows someplace no harm other than needing new wire. This assume the pv jacket is high cross-link polyethylene (XLPE)
For THHN the jacket melt time is 125 second. This jacket is PVC and has a much higher melting point.
In both cases it would take a bit over 2 hours to melt the wire in two. Say your breakers are at the house the solar panels are feeding the short. If your breakers are at the solar array the wires would pop there and hopefully not blow up the MPPT.
Interesting things that turn up when I ask questions and do the math. What does code say about this? Do the PV wires have breakers at both ends to cover all cases?
For THHN the jacket melt time is 125 second. This jacket is PVC and has a much higher melting point.
In both cases it would take a bit over 2 hours to melt the wire in two. Say your breakers are at the house the solar panels are feeding the short. If your breakers are at the solar array the wires would pop there and hopefully not blow up the MPPT.
Interesting things that turn up when I ask questions and do the math. What does code say about this? Do the PV wires have breakers at both ends to cover all cases?