AC arcs are easier to extinguish than DC arcs, but DC will creep much easier than AC and so on.
From a personal point of view: I've worked enough with both up to about 1KV at appreciable power levels and much higher than that at reduced power. Up to 50V or so I'd rather work with DC than AC but they're not much different. Up to 400V or so above that I'd much rather have AC and above 400V the answer is 'neither' because you're in some kind of gray zone where creep is still low so you won't know something is amiss until it is too late. And above 1KV in normal settings (say, picture tubes in old small b&w tvs and higher up when they're color and larger) and it will throw you right across the room but you'll likely live because the currents are low.
HF HV... now that's a different matter and I'm very respectful of anything in that domain, and still have a burn from a Tronser trimmer more than 45 years after it happened. Note to self: keep eye on SWR meter/Spectrum analyzer and finger position while trimming large end stages.
Can you say more about "creep"? Is the resistance changing? Or is material actually migrating?
Also curious why it's worse using DC.
Electromagnets dont work for DC, so your breaker will never trip. For thermal protection, you need current, so that checks out, and it would make sense for it to be rated under 50V as thats considered the highest voltage thats not life threatening on touch.
PV Batteries in general have a very high current (100s of A) at ~50Vish volts, so I dont think there's a major usecase for using household breakers for them.
Im still not getting your point BTW, switches and breakers are two separate things, with different workings, and household (and datacenter) DC would be I think around 400ish V, which is a bit higher than the peak voltage of AC, but still within the arc limits of household wiring (at least in 230V countries).
The advantage of DC is that you use your wiring more efficiently as the mean and peak wattage is the same at all times. Going with 48V would mean high resistive losses.
If electromagnets don't work for DC then what am I supposed to do with this pile of DC solenoids and relays? ;)
> PV Batteries in general have a very high current (100s of A) at ~50Vish volts, so I dont think there's a major usecase for using household breakers for them.
That's what the SCCR rating is for. When there's a fault you're going to have a LOT of current flowing until your safety kicks in. Something like the grid or a battery bank will happily provide thousands of amps almost instantaneously. Breakers designed for protecting building wiring are rated for this. Now, most household breakers aren't dual DC/AC rated, but you can actually buy DC rated breakers that fit in a home panel (Square D QO series).
> Im still not getting your point BTW, switches and breakers are two separate things, with different workings, and household (and datacenter) DC would be I think around 400ish V, which is a bit higher than the peak voltage of AC, but still within the arc limits of household wiring (at least in 230V countries).
My point is that there isn't any material reason why DC can't be as safe as AC, all the proper safety equipment already exists. Extinguishing a DC arc during a fault is a solved problem for equipment at household scale.
> The advantage of DC is that you use your wiring more efficiently as the mean and peak wattage is the same at all times. Going with 48V would mean high resistive losses.
I just mentioned 48V because it's a common equipment voltage for household DC systems. 400V would be good for big motors and resistive heating loads.
Regarding DC vs AC and wiring efficiency, talking about mean vs peak wattage just confuses the issue. 1 volt DC is 1 volt RMS. It is an apples-to-apples comparison. If you want to say "we can use 170VDC or 120VAC with the same insulation withstand rating, and at lower current for the same power", then that is absolutely true. But your common 600V THHN building wire won't care if you're using 400V AC or DC, so it's mostly immaterial.