Breaker size for FM 60...60 amp, correct?

FreewilleyFreewilley Solar Expert Posts: 223 ✭✭
My wiring centre is incorrect I have been advised...there is a 60 amp breaker between CC and PV array, but none between battery.
I am ordering breakers, should be 60 amp?
Also, is there a breaker or box that can stand alone nicely, my main panel is pretty tight.
Mate, VFX 2812, FM 60 & MX 60, 2 Full River AGM 400 6v, 1400 watt Solar Array, Yamaha 3000iSEB inverter gen
12 volt Flojet water pump
off grid summer home in northern Ontario

Comments

  • BB.BB. Super Moderators, Administrators Posts: 29,518 admin
    If you want full 60 amp rated output from the FM 60--then:
    • 60 amps * 1.25 NEC derating = 75 amps ~ 80 minimum breaker/wiring rating
    Was that your question?

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • BB.BB. Super Moderators, Administrators Posts: 29,518 admin
    I should add that outback may have 63 amp rated circuit breakers too. Different from NEC rating method.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • VicVic Solar Expert Posts: 2,970 ✭✭✭✭
    Hi Willey,

    First, you will want breakers rated for DC operation on the CC in, out, and on the inverter.

    A 60 A DC breaker is probably OK on the input of the CC.

    When choosing breakers (of fuses for that matter) just remember that the size of the cable dictates the maximum breaker size that you can safely use. And if a breaker rating is increased, please check that the existing cable will be able to safely handle the added current.

    You could use the MidNite MNEPV breakers -- they are Rated for Continuous current (unlike some, although not everyone likes this approach to rating breakers) The standard MNEPVs have ratings from 1 - 63 Amps, and take a single DIN breaker slot in standard Solar style boxes:
    http://www.solar-electric.com/instal...br1/mnepv.html

    Then there are DIN Rail mount breakers Rated at 80 and 100 A, that require two DIN breaker slots:
    http://www.solar-electric.com/instal...omn150vdc.html

    These breakers are a bit expensive, at about USD 40.

    Here is a box that will accommodate the DIN Rail breakers:
    http://www.solar-electric.com/instal...obigbabox.html

    This is the MN Big Baby box, which can accommodate up to four single-width DIN breakers (do NOT recommend using the Baby Box, as it is SO small that it is difficult to route cables, etc).

    Since you feel that you will need an additional box to mount the added breakers, perhaps you could consider the MNEDC breakers, which mount from the front:
    http://www.solar-electric.com/instal...amodccibr.html

    These breakers are relatively inexpensive, and have Ratings to 100 A (Continuous), with the standard single-width of 0.75" for this series of MNEDCs.

    This box, the MNEDC-Quad, will accept up to four of the 3/4" wide MNEDC breakers, and has a reasonable amount of room:
    http://www.solar-electric.com/installation-parts-and-equipment/midnite/elenanddcdi/mnedc-quad.html

    If you will need a Disconnect/Breaker for your inverter, the appropriate box to mount it, and the others that you want to add, would probably change.

    FWIW, Vic
    Off Grid - Two systems -- 4 SW+ 5548 Inverters, Surrette 4KS25 1280 AH [email protected], 11.1 KW STC PV, 4X MidNite Classic 150 w/ WBjrs, Beta KID on S-530s, MX-60s, MN Bkrs/Boxes.  25 KVA Polyphase Kubota diesel,  Honda Eu6500isa,  Eu3000is-es, Eu2000,  Eu1000 gensets.  Thanks Wind-Sun for this great Forum.
  • FreewilleyFreewilley Solar Expert Posts: 223 ✭✭
    Vic....thanks so much. You put a lot of effort into your answer and it is really appreciated.
    Mate, VFX 2812, FM 60 & MX 60, 2 Full River AGM 400 6v, 1400 watt Solar Array, Yamaha 3000iSEB inverter gen
    12 volt Flojet water pump
    off grid summer home in northern Ontario
  • ApplesApples Solar Expert Posts: 39 ✭✭
    Your battery positive should be fused/breaker'd for the ampacity of the cable connecting it, and within 6 inches of the battery positive terminal. That's what I hear, anyway. Dunno if the otherwise-very-helpful-and-informative replies touched on where, ideally, the battery's breaker should be placed.
Sign In or Register to comment.