The sum of the breakers in a panel exceeds the rating of the main breaker in almost all applications. This is because of the design usually anticipates that all devices won't operate at once or at full load. So if you had 100 Amp service and you had ten 20 Amp breakers each happily drawing 15 amps that would be 150 Amps and the main would trip. You need to heavy up your service.
You can't change the one breaker, but you can't use two separate arc fault breakers unless you separate the neutrals. However double pole arc fault breakers are made for this purpose and the common neutral would be O.K.
3 pole would be for 3 phase, 4 pole would be 3 phase & neutral
It sounds like the breaker is unserviceable. Seeing as it supplies 240 volt outlet it must be a two pole breaker. If it is a single handle two pole breaker then one pole set inside the breaker is not disconnecting one of the lines. If it is supplied from two single pole breakers that has a common tie, the common tie might be loose and does not shut off both poles when thrown to the off position. If there is no common tie then both breakers must be turned off to interrupt the 240 volt supply.
If by "60 amp box" you mean a 60-amp service panel (circuit breakers or fuses), you would generally get a 60-A panel that has several slots designed to accept a variety of compatible breakers, from 15A to 60A. If you have a "box" with no breakers, you would need another "subpanel", with wires from the 60A box to the new subpanel, and install one or more 15A breakers in the subpanel. If you don't need more than one breaker, you might also simply use a 15A disconnect panel with a single breaker in it.
Yes. An everyday occurrence of this circuitry is in your kitchen counter split receptacles. The top half of the receptacle is a 15 amp circuit and from the same breaker the bottom half of the receptacle is another 15 amp circuit. A two pole single handle breaker is a common trip. If one of the circuits fed from the breaker faults the other connected circuit will shut off also. If you are talking about slot position in a breaker panel, you can remove the two pole breaker and install two single pole breakers.
The electrical terminology for this type of breaker is a tandem breaker. It is where two breakers circuits can be in the same one breaker slot in a distribution panel. On this type of breaker there will be two output for a circuit value of what ever the breaker is rated for.
It will if the 100 amp distribution board is a 20 circuit board. Ten spaces for the 240 volt breakers and seven spaces for the 120 volt breakers. There are two types of 100 amp breaker boards, one rated at 100 percent and the other at 80 percent. Depending on what rating on the panel board you are using will govern the maximum amount of current that can be legally drawn from the board. This breaker board rating will also govern the size of the main breaker installed and the wire size to feed the board, either 100 amp wire or 80 amp wire. The second consideration is what are the connected loads to the breakers, with the total of seventeen breakers, the board can only supply as much amperage as the main breaker will allow.
250AF refers to the ampere rating of the breaker frame and 200AT refers to the breaker trip rating in amps. These are not breakers that you would find in your home but industrial molded case breakers. The current trips can be changed out to different values all within the same frame size.
Small size home breakers have a fixed setting and can not be adjusted. Three phase moulded case breakers have adjustable trip settings on the load side of the breaker. These overloads can be set for motor inrush to stop the breaker from needless tripping and yet still protect the other equipment down stream from the breaker.
I am assuming by your description that the panel is protected by a 90 amp breaker and the breakers in the panel when added up is 200. This is okay as long as your 90 amp breaker trips on a regular basis. It is typical for the breakers to add up to more than the main breaker under the assumption that you would rarely be running each circuit at its maximum capacity.
No, you cannot install a 2x20 amp breaker if the total amperage of all the breakers exceeds the main breaker rating, as this would overload the system. The total amperage of the breakers should not exceed the main breaker rating to ensure safe operation of the electrical system.
If you mean can you put a single 20 amp breaker in an electric panel, the answer is yes. An electric panel is typically made to handle more breakers with values that add up to more than the rating of the panel on the supposition that you will never draw full load on all breakers. If you do the main breaker would trip. In your case you are under utilizing the panel, but this is not a problem.