Forum Discussion

Almot's avatar
Almot
Explorer III
Feb 09, 2014

80VDC 10A fuse?

Thinking of arranging my solar setup "the right way" - add all the recommended fuses, like PV fuse, battery fuse, controller fuse and load fuse. It works as it is, so I'm going against the rule "it works - don't fix it" :)

Suddenly discovered that there are no fuses rated over 32VDC, at least within reasonable price. My array has 60 Vmp, 8.1 Imp. So I need a fuse rated 80VDC 10A (or 15A?), and don't see any. Breakers - yes, but not fuses.

I have already decided (99%) in favor of set of breakers and a box like Baby Box or Big Baby, from Midnite Solar. This would take care of 80VDC fuse as well, and easier to switch off any components than with blade fuses. It will also have a room for Pos and Neg buses, everything in the same enclosure. But maybe I'm missing something?

Oh yeah, and the battery fuse will be a separate fuse from Blue Sea, screwed right on the terminal where it belongs, so it's not really "all in the same enclosure" - just didn't want to dilute the topic. The question is mostly about 80 VDC PV fuse.

39 Replies

Show More
  • Almot's avatar
    Almot
    Explorer III
    Feb 09, 2014
    HVAC and Enblethen - I am trying to avoid using AC fuses with similar ratings. 250VAC fuse will probably support 80-90VDC, but God knows what will be its Amp rating in DC current.
  • pianotuna's avatar
    pianotuna
    Nomad III
    Feb 09, 2014
    Hi Almot,

    Then put in a disconnect switch. Far cheaper.

    Since you asked--yes I would fuse at 30 amps. I have no fuse between my panels and the controller--but I do have switches and a fuse at the battery bank.

    smk should not use alternating current fuses/switches--they are not rated for the arcing that may happen.
  • Almot's avatar
    Almot
    Explorer III
    Feb 09, 2014
    SMK, I know that my array doesn't need a PV fuse. What I need is an easy way to disconnect it when I have to, ex. working on anything downstream. So the fuse or breaker would serve such a purpose. My controller, same as many other, requires disconnecting PV before the battery. Your system is 100V, so you can use AC switches/fuses, but mine is 60V.
  • time2roll's avatar
    time2roll
    Nomad
    Feb 09, 2014
    Series panels don't need a fuse. The ampacity of the wire can easily handle a short circuit. With 8a available you will never open a 10a fuse let alone warm up #10 wire..

    Parallel panels need fuses as the total amps can exceed a single panel branch circuit.

    With that said I have a high voltage switch to cut panel power from the controller. Inside this 240v switch is a pair of Edison fuses rated 10 amps. Switch was about $15 at Home Depot.com, fuses from amazon.
  • Almot's avatar
    Almot
    Explorer III
    Feb 09, 2014
    OK, Bussman have 600VDC fuses. Need to think. Haven't seen any big stores selling these fuses or blocks.

    Don, the wire from 8A array is #10 - naturally. Ampacity = 30. Do you suggest 30A fuse?

    Resettable breakers... Those DIN rail DC breakers for Baby Box are resettable, but not auto-resettable.
  • enblethen's avatar
    enblethen
    Nomad
    Feb 09, 2014
    Check West Marine!
    The cartridge style fuses shown on Midnite solar website should be available at Lowes or Home Depot. They could be KTK, KTQ or min series.

    Lowes fuse
  • Golden_HVAC's avatar
    Golden_HVAC
    Explorer
    Feb 09, 2014
    Check Graingers.com and page 270 of the current catalog. It looks like 1CJ37 is rated at up to 250 volts and 15 amps. I don't know if it is 250 VAC only, or if there is a DC voltage limit. My guess is normally the DC rating is slightly less than the AC rating. DC is more likely to ark across the fuse material once it has blown, and thus you have a lower DC rating than AC rating.

    So you should have at least 90 VDC rating, or can select the correct fuse from several on that same page.

    Fred.
  • pianotuna's avatar
    pianotuna
    Nomad III
    Feb 09, 2014
    Hi Almot,

    What size is your wire? I would fuse to wire size rather than the current. If you do go for a circuit breaker I'd pick an auto reset type.

About Technical Issues

Having RV issues? Connect with others who have been in your shoes.24,283 PostsLatest Activity: Jul 17, 2025