I liken this converstaion about the differences between 30a and '50a' akin to the building industry's '2x4' stud:
which is not actually 2" x 4" as you might assume, but closer to 1 1/2" x 3 1/2"
why? if you're not in the industry it's probably a lost conversation, but like the '50a' scenerio, it comes from years of terminology that trickles down to everyday usage... though it doesn't always make great sense to us 'normal' thinkers.
30a is only a total of 30a
available to any and all usage within your coach
'50a' is a total of 50a available on both 'sides' of your coach
: your breaker box will have a double-pole 50a breaker which divides what items are available on that specific side of the breaker ...
- one 50a side of the breaker serves items such as an air conditioner, microwave, electric water heater, some lights, some 110v outlets, etc.
- the OTHER side of the breaker serves the other air conditioner, refrigerator, tvs, slides outs, engine block heater, some lights, some 110v outlets, etc.
... so, in essence, you have a maximum of 100a for your coach, which is 70a greater than the 30a
option. In temperate weather, 30a is probably satisfactory for most coaches, even the larger ones, but when the a/c units and heat is needed, sometimes 100a is required in order to maintain all the other electric needs while these are functioning(especially during the hot summer months)...
When you have the 50a double-pole breaker trip, though, it means that one SIDE of your usage exceeded the 50a maximum - such as when you run the a/c unit, have the electric water heater element on, and turn on the microwave, all while several tvs and receivers are working, and two iPhones and several devices are all charging on 110v outlets.
Most of the time, high voltage/amperage devices cause these tripping issues, like using a toaster, or electric heaters.
When you reduce down to 30a service, you have to be aware of what items are being used, especially if needing to use an air conditioner. The more you are in these situations, the more you learn about how to manage it - turn the a/c off when using the toaster, etc.
One thing to also consider as part of the mix: your 'Shore Max' setting
on your Inverter/Charger unit/panel. This setting tells the Charger how much amperage(amps) you are willing to allow the Charger to use to charge the batteries while you are on Shore power, or even on the Generator. The higher the amps you allow, the LESS room you have for air conditioners, microwave, heaters, etc.
before you possibly trip the shore power's breaker, or the generator breaker(even worse).
If I am plugged into 50a shore power
, I can set the 'Shore Max' setting to a higher number, such as 50a, because I have a total of 100a possible, though i can lower this setting, such as 10a, during summer Hot months when both a/c's are needed. This keeps the coach breakers from tripping. A higher 'Shore Max' setting basically allows the Charger to more quickly recharge your batteries...
which may not always be your priority.
If I am plugged into 30a shore power
, I set it much lower, to either 10a or even 5a so that I have more available power for the other items in the coach, especially if an a/c unit is needed.
If I am plugged into a reducer to 110v/20a(or even 15a) residential outlet
, I set it on 5a, or even turn the Charge OFF in order to let all of the available power be used within the coach - even this residential outlet can power an a/c unit if worked properly, and very little else is used: turn off the electric water heater, all devices charging, etc.. and don't use the microwave while the a/c is running. The length of any additional power cord is also a consideration.
so much to think about, but you get used to it the more you travel and the more 'situations' you are in - such as when dry camping, or on a residential outlet.