Figuring out Breaker Sizes For a 48V Off-Grid System

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  • TecnodaveTecnodave Registered Users Posts: 437 ✭✭✭✭
    edited April 2019 #32

    BB,

    We think alike, I do very conservative wiring, My MS-4024AE is fed with 4/0 and the Cotek with 2/0 extra fine welding cable. I am looking to not waste power heating the wire. I have never had a burn down situation. When I do an installation it is understood that I will be back several times in the first 6 months at no extra charge, that's included in the installation. I like to get a continuing service agreement so that if something is amiss I can catch it before it balloons.

    I haven't peeked into the NEC itself in quite a while, I take the shortcut..."understanding the NEC" makes it clear without all the unneeded stuff.

    Im way overloaded right now, did a real nasty 200 amp 480 three phase Friday morning that had large puddles of formerly molten aluminum buss bar in the bottom of the compartment , I just had to secure the scene and keep people out of there. Steel frame steel skinned building, box got so hot the paint bubbled up, one phase still live, don't know if box is hot or not, raining.....all the nasties...utility transformer right above 75+ kWh, 2 of the 3 5,000 volt primary fuses blown out of the cartridges, one phase hot with no way to shut it down. Pigs,Goats, and Elephants got out there pretty quick! I got a proper scolding from them for even touching it!

    One of my freind's is a water pump contractor, He told me that electricians don't like water and plumbers don't like electricity, I stand here knee deep in water doing electrical water pumps!

    david

    2 Classic 150, 2 Kid, 5 arrays 7.5 kw total  2ea.  2S6P Sharp NE-170/NE-165, 1ea. 12P Sanyo HIT 200,  2ea. 4/6P Sanyo HIT 200, MagnaSine MS4024AE, Exeltech XP-1100,  2 Banks L-16 battery, Rolls-Surette S-530 and Interstate Traction, Shunts with whizbangJr and Bogart Tri-Metric, iCharger i208B  dc-dc buck/boost converter with BMS for small form lithium 8S 16650 or LiFePO4,
  • BB.BB. Super Moderators, Administrators Posts: 32,331 admin
    edited April 2019 #33

    Throw in residential electricians that never did multi-hp motors taking on a commercial job, and DC solar (1,500 Watts, that will take 14 AWG circuit just fine--Opps, that was 12 VDC input and needs a 150 amp circuit)... And it is amazing what is out there.

    Stay safe David,

    -Bill

    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • TecnodaveTecnodave Registered Users Posts: 437 ✭✭✭✭

    The burnout was caused by another contractor who upgraded a circuit in the building for the owner of the property to power a 40 foot shipping container referigerator to store herbs in. The owner requested a 480 volt circuit be installed for the reefer unit. I work for the former owner of the building who sold it to the current owner with a net net net lease back. I provided an existing circuit that I didn't need for the tenant's use , the other contractor came in and upgraded that 480 wye service from 40 amps to 70 amps and did the drop to the reefer box just outside, hooked it up without checking the specs and wiring of the reefer box. It was wired 240 delta hi-leg three phase, it burned everything out. A referigeration contractor came in and rebuilt the referigeration units and fired everything up........Magilla not over......owner fills unit with herbs and spices Wednesday ..........main box blows out Thursday night! Crew for my customer comes in Friday morning and electric is funny....480 wye to 240 delta transformer making noise 277 volt lighting flickering.......I race over to diagnose the failure and found the damage to the building.....I had to order both tenants out and keep control of the scene until I could get PG&E out there. I will not be stepping into that Magilla. Wow! Two major contractors blowing it at the same job! The electrical contractor is a big one in Santa Cruz.....he is eating it big time! He is allready on the hook for the reefer and now the whole service. I have allready refused to get further involved in that one. I maintain multiple buildings for the tenant and my responsibility is to the tenant and crew. please just keep me outta this Magilla......it gets exciting sometimes

    david

    2 Classic 150, 2 Kid, 5 arrays 7.5 kw total  2ea.  2S6P Sharp NE-170/NE-165, 1ea. 12P Sanyo HIT 200,  2ea. 4/6P Sanyo HIT 200, MagnaSine MS4024AE, Exeltech XP-1100,  2 Banks L-16 battery, Rolls-Surette S-530 and Interstate Traction, Shunts with whizbangJr and Bogart Tri-Metric, iCharger i208B  dc-dc buck/boost converter with BMS for small form lithium 8S 16650 or LiFePO4,
  • Sunny-HTISunny-HTI Registered Users Posts: 20 ✭✭

    Absolutely BB. As I have mentioned in my post: " I am solely responsible for what I do ".

    You folks are trying to help us the best you could, and the least we could say is :" Thank You" .

    We owe it to ourselves to do our own research as well, and not blindly execute everything we read on the Internet.

    This Russian proverb, a favorite of one of our past presidents, is timeless:

    “Doveryai no proveryai” — Trust, but verify.


    48V Off-grid System - 1890W panel array (6 x 315) in 3S2P configuration, MNPV3 Combiner, MNDC Enclosure, Whiz Bang JR, Classic 150 CC, 2.5K Inverter Cotek SD-2500-148, 4 x 12v 204 AH FLA Trojan (SPRE 12 225)...

  • Sunny-HTISunny-HTI Registered Users Posts: 20 ✭✭

    Thank you for your contribution to this post, I have learned a lot, more ha I was bargaining for - lol

    As my trip is approaching, I would like to complete my equipment purchases. Would the following be acceptable choices?

    100 Amps Panel breaker - 100 Amps in line fuse near the battery - #2 Awg Battery/inverter cable

    125 Amps Panel breaker - 125 Amps in line fuse near the battery - #1 Awg Battery/inverter cable

    I have attached a picture of the inverter wiring.

    Regards,



    48V Off-grid System - 1890W panel array (6 x 315) in 3S2P configuration, MNPV3 Combiner, MNDC Enclosure, Whiz Bang JR, Classic 150 CC, 2.5K Inverter Cotek SD-2500-148, 4 x 12v 204 AH FLA Trojan (SPRE 12 225)...

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