AC Breakers vs Fuses?

Rednecktek

Solar Addict
Joined
Sep 8, 2021
Messages
782
So I have seen a few videos where the person used a 3ph A/C breaker as both the battery disconnect and the protection rather than just bolting in a fuse or block and having to break out the wrenches if it needed servicing. Is this a bad idea for any reason? It seems that if you have the space it just makes life easier.

Of course I'm talking about something like Siemens or Hyundai, not Harbor Freight. :D
 
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A.Justice

Swears he didn't start that fire.
Joined
Sep 12, 2020
Messages
833
Location
TN
Switching any type of breaker on and off while under load can damage it.

There's a lot of people on here that use their breaker as a main disconnect switch, and that's probably okay, as long as you don't have high amperage passing through it while it's switched. Turning off loads, THEN turning off the breaker would be best practice.

Personally, I use fuses and a switch. I would also use a breaker and a switch if I decided later to use a breaker as opposed to a fuse.
 

rmaddy

Full-time Solar-powered Trailer Life
Joined
Nov 16, 2019
Messages
1,692
Location
USA
Do not use AC breakers/fuses on DC circuits or vice versa. Use quality components meant for a specific task.

Use a proper fuse for your battery. Want a battery disconnect? Use a proper disconnect switch. Two different jobs.
 

OffGridInTheCity

Solar Addict
Joined
May 23, 2021
Messages
554
Location
Southern Oregon
I use breakers - for wire protection but also as on/off to work on things.

As mentioned above, do not use AC breakers for DC current - they are designed differently to handle the 'arc' when opening the circuit. In a worst case, an AC breaker could 'fuse open' and enable a bad current flow situation, perhaps even lead to a fire.

I use UL (or ETL) listed breakers such as Midnite Solar like this - https://www.amazon.com/MidNite-Solar-Breaker-150VDC-MNEPV60/dp/B00BSYSLXU/ref=sr_1_5. They are UL, and can be used for reasonable on/off and range from 5a to 100a in DIN rail style mounting - and then screw in style up to 250a. For shunt-trip / high amps - 100a, 200a, 300a, 400a, .... I use ABB SACE models like this - https://www.ebay.com/itm/265303457586?hash=item3dc5517f32:g:MksAAOSw9eRhLByk for a reasonable price for 'very advanced' engineering (safety). I have a 400a S3 w/24v shunt-trip version on my battery bank.

I'm not against FUSES or other UL/ETL breakers - just happened to settle on Midnite and SACE and can recommend them from practical experience. :)

I would avoid cheap breakers like this - https://www.amazon.com/gp/product/B07CXYGBGH/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1 I find that when you cycle them on/off just a few times (10 times) they will break.
 
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