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LINE or LOAD?

RCinFLA said:
Positive lead from a PV panel will be to the '+' marked terminal because the breaker contact resistance voltage drop will result in slightly lower voltage on other side of breaker switch. The negative lead from PV panel will go to the terminal marked with '-' since it will be the slightly more negative voltage compared to other terminal of breaker switch contact.
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That would short the PV panel since as soon as the breaker was closed, + and – would be connected.

The + (LINE) and – (LOAD) on DC directional breakers don't refer to the literal positive and negative on PV panels, batteries, etc.

It just means that the LINE side of a DC directional breaker has more potential than the LOAD side.

So to answer my original question . . .

For a DC directional breaker between the Batteries and a Controller, the Battery side would be the LINE side.

For a DC directional breaker between a PV array and a Controller, the PV array would be the LINE side.

See MidNite Solar's Secrets to DC Breakers.

nc73 said:
My breaker is upside down...works fine
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Until it doesn't. See MidNite Solar ETL Testing.
 
The side with more power potential needs to go to the NON-MOVING part of the breaker to lessen the chance of the moving bits flying around in there and causing even more problems if the shit hits the fan.
 
How about this breaker. My batteries are connected to load, inverters to line.1666365401651.png
 
That's the one signature solar is selling for this purpose. So I bought it on their recommendation and apparently many others did as well. Maybe one of them will chime in
 
bones1 said:
Didn't want to mount it upside down, does it really matter?.
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AC breakers do not have polarity and should not be used for DC current. For 48v battery line you can get away with it, but tying two breakers in parallel to get greater current is just bad.
 
Are they selling the wrong breaker for this purpose? Liability issues here?
 
RCinFLA said:
AC breakers do not have polarity and should not be used for DC current. For 48v battery line you can get away with it, but tying two breakers in parallel to get greater current is just bad.
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Here is the product link.
signaturesolar.com

Nader DC Circuit Breaker | 60V 200Amp

Signature Solar provides solar panels, off-grid solar systems, grid-tie, and hybrid systems. Quality solar inverters, bifacial solar panels, complete solar kits, solar batteries. Featuring brands such as EG4 Electronics with their solar battery, LifePower4 and EG4 LLifePower4 and EG4 LL
signaturesolar.com signaturesolar.com
 
It's a DC rated breaker.
Maybe dual rated (not sure).
Parallel conductors and OCP is done quite often. The same principles apply to both.
 
Last edited:
Is it the perfect way to do it ? Dunno, but Sol-ark do it and I have seen it done on APC industrial gear so it must be OK.
 
It is also approximately but in the context of voltage it is AC. The = sign where the lower bar is broken/dashed means DC. Never seen electrical equipment rated as approximately.
 
Ellcon123 said:
It is also approximately but in the context of voltage it is AC. The = sign where the lower bar is broken/dashed means DC. Never seen electrical equipment rated as approximately.
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I typed something to the effect of I had ~15 fuses blow in my lifetime.
As in approximately 15 fuses in my life.
AC and DC are pretty short and well understood acronyms so most folks won't go hunting for the symbol.
 
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