Paralleling 2 non polarity dc breakers

bigbrovar
bigbrovar Registered Users Posts: 32 ✭✭
in Off Grid Solar & Battery Systems #1
Hello everyone,

I need to add a breaker between my charge controller output to the battery busbar. The charge controller output about 100A but I have a 100A non polarity DC breaker which run very hot when the cc is at peak work hours.. pushing out about 95A.

I was considering running another 100A breaker using a Y connection ie terminate the cable from cc to a point and draw 2 equal length wires from that point to the 2 breakers. The breaker output would also be equally terminated to the battery busbar.

What are the dangers of this approach?
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Comments

  • NANOcontrol
    NANOcontrol Registered Users Posts: 280 ✭✭✭
    #2
    Are you just looking for a disconnect? Your breaker operates on heat and you can't escape that fact. Your single breaker probably won't even trip at 140A.  I test a lot of breakers and many just don't qualify as useful protective devices.
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,716 admin
    #3
    I would not parallel breakers--But just get a larger Amp rated breaker and the wiring to support that current.

    Normally, I suggest that Branch CirFcuits that are carrying "continuous loads" (such a gym lighting, large fans, and battery charging) use the NEC derating of 80% (at least) for branch circuits that are subjected to continuous loads (hours or more at "full current")...

    For example, a 100 Amp breaker+wiring:

    100 amps * 0.80 = 80 amps suggested max continuous current

    Or for a 100 amp continuous load:

    100 amps * 1/0.80 (or * 1.25 NEC derated) = 125 Amp minimum rated branch circuit

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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