I once lived in an apartment where the dishwasher's motor failed short and caused a breaker to trip
That is the expected behavior, yes... In a short circuit condition, one of the current interrupt devices, be it fuses or breakers that is in series with the load (in this case, a short circuit) is supposed to open when extreme fault currents are present on the line... And open safely! This is the reason for maximum fault current ratings on things like circuit breakers and the HRC fuses you want to have installed in your multimeter when you go probing around in said low-impedance, ridiculously powerful areas.
-- but not the 15 or 20 amp (I forget) breaker in the panel in the unit, but instead the 60 or 100 amp breaker in the main panel for the building tripped on one side of the 240.
Depending on where along the chain of the potentially many-layer <sub-device fuse> - <power supply fuse> - <branch circuit breaker> - <sub-panel circuit breaker> - <main panel circuit breaker> - <distribution breaker> - <transformer fuse> area of the circuit that the actual fault occurs, there can be many different places that are likely to open.
Obviously, a dead short in a (hopefully) well connected device like a dishwasher will (at least in a good, low-impedance mains system like I'm used to here in Canada) cause a surprisingly large current to flow, even in relatively low cross-section conductors. I meant to point that out in the recent thread about the AC or heat pump system with the 30 vs 40 A breaker on 10ga wire discusssion.
When that kind of fault current happens, any of the upstream protection devices may open depending on their total instantaneous load, long term heating, device life issues, etc. etc. The fact that a
mains type breaker opened instead of a
branch type breaker is irrelevant. It was a low impedance short... Personally, I would almost
want the main breaker to be the one that opened, to take the blast since it should be rated at least as high if not higher than any downstream branch breaker as far as fault current interrupt ratings are concerned.
In this case it seems that the mains-style breaker didn't survive opening on a reasonable downstream surge, rather than some horrendous fault current blasting it open, which is why it seems that it is a somehow flawed, faulty breaker. They should be able to survive way more than that!
Lessons: yes, faulty old breakers can trip too easily. Also, multi-pole "handle-tie" breakers suck.
I don't understand, you mean that a one-side overload tripped both sides (or all 3) of the upstream breaker? That is by design.
Yeah, I've seen that too. But it was an FPE panel and breakers. Probably somewhere between the 4th and 5th time they filed bankruptcy for substandard equipment. LOL
I've always liked the Federal Pioneer stuff and it is my preferred brand, though now that Schneider basically killed it off (probably mostly just strategically, of course,) as stock dries up I pretty much have been starting to have to use Square-D (my second choice) or least desirable like the CH / Eaton / Westinghouse / Siemens style.