One characteristic of adding PV solar to homes is a massive increase in high-voltage and high-current DC installations. With this comes a need for suitable breakers, but without the requisite knowledge it can be easy to set up a fire hazard. There is also the issue of online shopping platforms making it easy to get fuses and breakers that may not be quite as capable as they claim, never mind being rated for DC use.
Recently [Will Prowse] had a poke at a range of common purportedly DC-rated breakers from everyone’s favorite US-based seller of tat, to see whether they should be bought or avoided at all cost. Perhaps unsurprisingly the cheap breakers are about as dodgy as you’d imagine. With a hundred plus amps flowing through them they get surprisingly crispy, even if they generally did their job. Minus the few that arrived in a broken condition, of course.
Ultimately [Will] found that the molded case circuit break (MCCB) by one ‘DIHOOL’ performed the best. Compared to the competition, it is much larger and has sizeable terminals that avoid the quaint heat-soaking issues seen with the cheap-and-cheerful rest. At a mere $34 for the 125A-rated version, it’s still a fraction of the cost of a comparable Eaton MCCB, but should upset your insurance company significantly less than the alternatives.
Don’t forget to add in fuses, with [Will] testing a range of cheapo 12V DC fuses, to see which one will prevent fires, and which one cause them. Unsurprisingly, some of them like the Bojack-branded ones ran very hot, making them more of a liability than an asset.
As for what makes DC breakers so different from AC one is that the extinguishing point of a DC arc is much steeper, which means that an AC breaker is likely to fail to extinguish the arc when used for DC applications. This is why a properly rated and ideally certified breaker is essential, and also not really the point where you want to start saving money.
PLEASE don’t be buying dodgy no-name circuit breakers or fuses. For 12/24vDC your local Napa Auto Parts store will have better quality options from known brands with established quality control.
They have Bussmann TypeIII resettable circuit breakers good for 30vDC from 25a up to 200a, including marine grade. Your DIY auto parts retailers might not carry these, but it’s worth a look.
Those MEGA fuses are better known in the automotive industry as AMG fuses. (No, not Mercedes-Benz AMG, AMG is the fuse type and size standard nomenclature.) Any auto parts store will carry those, although your amperage options may differ by retailer.
If the kid behind the counter stares at you with a blank look on their face, tell them to get someone from the commercial counter; they’ll know more and probably be ASE certified.
For 48vDC, find a golf cart shop.
I think your advice is spot on, but wanted to add something re: MEGA fuses.
Pretty sure “MEGA” is just the brand name that Littelfuse uses for their AMG size/type fuses (and possibly some other high amperage automotive DC fuses?)
So for folks that don’t have a good local auto parts store, looking specifically for MEGA fuses rather than AMG may actually help you get a name-brand fuse from a trustworthy (as far as I know) manufacturer.
“DIHOOL”, “kmkhfc” or “Intrinsic Penis” are all disposable Amazon brands used for dropshipping lowest quality crap from PRC. By not buying their shit (even if it’s for a joke project or YouTube video) you’re doing your part towards starving their economy.
Standard Square D QO breakers are good to 48vdc and are fairly cheap. Easy to find anywhere, I’d trust those more than whatever amazon is hawking
UL markings and all the rest means nothing these days. The governing bodies don’t have the ability or knowledge to enforce . It’s just a bunch of low Ed admin people in an office sucking money from governments
Got any facts to back that up? The UL listed devices I buy from Digikey/Mouser/etc or my local electrical supplier are always more reliable and higher quality than the Bunch-Of-Syllables garbage from Amazon.
UL is one thing but the most 🤡🤡🤡🤡🤡 thing is CE mark which was originally designed by EU government to mean “Creatsione Europa” (Made in Europe) but China copied and reused that mark as “China Export”.
(Anyway, the whole EU project is a failure and should be disbanded like Gorbachyv did in 1991.)
UL is just another NRTL; that is, it’s essentially a North American ‘Notified Body’. UL is no more competent, or stupid, than any other test house. It’s just that UL and FM used to have an illegal monopoly on test marks for the USA, so their name became synonymous with test certification in North America. UL is so rote, that it has become anti-technology.
‘CE’ is not a test mark. The basis for applying a CE mark is the someone has written a Declaration of Conformity, claiming a basis for the presumption of conformity to one or more of the many EU directives.
‘Creatsione Europa’? Citation for that? I thought the original acronym was for Conformité Européenne.
Most Europeans, that I know, think well of the EU ‘project’. Personnally, I think that the governments doing the worst for product safety are Germany, Italy, and the UK (no longer an EU member), and have nothing to do with the centralized shenanigans coming out of Brussels.
Gorbachev’s poorly-designed reforms left the world a mess to clean up. The Russians seemed to not like his idea of reform in the direction of social democracy. The internal rebellions broke their economy, with the ‘citizens’ welcoming Putin to power. The Russian fiasco is a poor analogy for the formation and performance of the EU.
As someone who has gotten device approved and tested at UL and having toured their facilities in Illinois, I can assure you that they do real and stringent actually testing devices to failure. They definitely do not rely on anyones “declaration of conformity” in their process. Their “underwriters” title is what matters, their original purpose was to prove to insurance companies that a product was not likely to cause an accident or damage that would cause a payout. Much more pure motivation than some government agency would have.
Look into aviation breakers. They have to be certified. Pricey, though.
They aren’t actually all that bad at about $25 each. Check out Aircraft Spruce for one source.
https://www.aircraftspruce.com/menus/el/circuitbreakers_klixon.html