Depends on the manufacture of the water furnace. Look at the data sheet or data plate on the furnace of contact the manufacture.
A 50 amp breaker is an overcurent device.
Use a 30 amp breaker.
The size breaker you use is determined by the size wire used in the circuit. If you use AWG #12/2 wire then use a 20 amp breaker. If you use AWG # 14/2 then use a 15 amp breaker.
Depends on the wire size you are using. If the generator breaker is a 30 amp then install a 30 amp breaker.
AWG 12/2 requires the use of a 20 amp single pole breaker.
#12/2wground & a 20 amp breaker should be enough for lights,receptales.
You use the correct size breaker depending on the size wire in the circuit. If the circuit is wired with AWG #12 wire use a 20 amp breaker. If it is wired with AWG #14 wire then use a 15 amp breaker.
Depends on the wire size used in the circuit. If you use AWG # 14 wire you must use a 15 amp breaker. If it is wired with AWG # 12 wire then you use a 20 amp breaker. If a AWG # 10 wire is used then a 30 amp breaker is required. The breaker protects the wiring from overheating so you must use the proper size breaker for the wire used.
Yes.
If you are referring to a cloths dryer, the answer depends on the requirements of the dryer. Most dryers require AWG#10 wire with a 30 amp fuse. If the wiring is AWG#12 then use a 20 amp breaker but never use it on AWG#10 which requires a 30 amp breaker. If you are referring to a hair dryer then yes a 20 amp breaker is fine.
25 amp breaker
Not unless the wire going to the refrigerator outlet is AWG 10/2. If it is wired with 12/2 wire then you must use a 20 amp breaker. Using a 30 amp breaker is dangerous and a fire hazard.