dougbert
Solar Addict
I don't have the 18kPV, but the design would work for other inverters
Last edited:
Wish I knew about this alternate wiring method without using a transfer switch, "feeder tap", breaker, and interlock
- Thread starter dougbert
- Start date
dougbert
Solar Addict
Youtube video
alternate wiring in lew of a transfer switch
comment on YT on this wiring
From this I can see I have a similar problem on my wiring
I am set to fix that
@jmuller86
Nice upgrade to the wiring configuration. Putting your new disconnect above the main panel sideway would be fine, no prohibition on that in the NEC.
But I see that you have two neutral conductors terminated on the EG4 neutral busbar. Both of those originate from your main panel, one going through the new 70A disconnect above and then down the new LFMC to the inverter, the other going down through the LFMC that goes out the bottom of the main panel to the inverter.
If you think about it, those two conductors are in parallel: they both originate at the same busbar (main panel) and ultimately terminate at the same busbar (inverter). Which means that constitutes a 310.10(H) violation, as they are smaller than 1/0.
Perhaps more importantly, any neutral current between the inverter and the main panel will divide along the two paths, regardless of the state of your interlocked breakers. So you'll have a 300.3(B) violation, as not all the conductors of the circuit are in the same conduit.
The solution to both problems is to use only one neutral conductor between the main panel busbar and the inverter busbar, and to route it along with both your (2) interlocked 70A breaker ungrounded conductors and your (2) new 70A tap conductors in a single conduit run that has all 5 conductors.
You can use either the upper route through the new 70A disconnect, or the lower route through the bottom of your main panel.
If you use the lower route, then you could also delete the neutral wire that goes from the main panel to your new 70A disconnect. Plus the lower route is shorter, so it looks like you'd be under 24" and not have to worry about derating for 4 CCCs.
alternate wiring in lew of a transfer switch
comment on YT on this wiring
From this I can see I have a similar problem on my wiring
I am set to fix that
@jmuller86
Nice upgrade to the wiring configuration. Putting your new disconnect above the main panel sideway would be fine, no prohibition on that in the NEC.
But I see that you have two neutral conductors terminated on the EG4 neutral busbar. Both of those originate from your main panel, one going through the new 70A disconnect above and then down the new LFMC to the inverter, the other going down through the LFMC that goes out the bottom of the main panel to the inverter.
If you think about it, those two conductors are in parallel: they both originate at the same busbar (main panel) and ultimately terminate at the same busbar (inverter). Which means that constitutes a 310.10(H) violation, as they are smaller than 1/0.
Perhaps more importantly, any neutral current between the inverter and the main panel will divide along the two paths, regardless of the state of your interlocked breakers. So you'll have a 300.3(B) violation, as not all the conductors of the circuit are in the same conduit.
The solution to both problems is to use only one neutral conductor between the main panel busbar and the inverter busbar, and to route it along with both your (2) interlocked 70A breaker ungrounded conductors and your (2) new 70A tap conductors in a single conduit run that has all 5 conductors.
You can use either the upper route through the new 70A disconnect, or the lower route through the bottom of your main panel.
If you use the lower route, then you could also delete the neutral wire that goes from the main panel to your new 70A disconnect. Plus the lower route is shorter, so it looks like you'd be under 24" and not have to worry about derating for 4 CCCs.
