Assuming you are referring to a 240 volt residential hot water heater you will need to install 10/2 NM cable (Romex) with ground from the service panel to the water heater wired to a 30 amp circuit breaker in the service panel. If you cannot see the water heater from the service panel you will need to install a service disconnect at the water heater.
The breaker size for a hot water tank is dependant upon the wattage of the tank. Most common households water tanks will be run on a two conductor #12 wire and the breaker protecting that size of wire is a two pole 20 amp breaker. This size will be used on a tank with wattage's up to 3840 watts.
Branch circuits are protected by the circuit breaker found in the electrical panel. Each circuit should have its one breaker. The breaker should be rated to protect the insulation of the wire, so you can determine the breaker size based on the circuit conductor size Example #14-2 should be protected by a 15 amp breaker
When installing a circuit breaker, you size the breaker based on the wire size. The breaker should be matched to the ampacity of the wire to ensure proper protection against overloads and short circuits. The device being controlled by the breaker is not a determining factor in sizing the breaker.
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.
A 15 amp dedicated circuit breaker should be used for the dishwasher. The disposal can be wired to the general kitchen 15 amp circuit.
Depends on how many amps it pulls and the size of the wire in the circuit.
The pool light is usually on a 15 amp circuit. The breaker feeding this circuit must have a GFCI rating.
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.
A circuit breaker protects the wires that the devices are connected to. If the devices that are connected to the circuit are 20 amps the wire size should be #12 wire fed from a 20 amp breaker. This breaker should not trip unless the circuit is overloaded or a fault occurs on the circuit. If the devices that are connected to the circuit are15 amps the wire size should be #14 wire fed from a15 amp breaker. This breaker should not trip unless the circuit is overloaded or a fault occurs on the circuit. Putting 20 amp sockets on this 15 amp circuit will work but the circuit is limited to the amount of load that can be plugged in. You will not get the full capacity of the 20 socket because the breaker will trip at 15 amps.
The sizing of the circuit breaker and hence the wire size to feed the pump are all dependant upon the amperage of the pump. This question can not be answered without that information.
In North America the standard sizes for breakers are 15, 20, 30, and 40 amps. The 15 amp size breaker is used in general circuit wiring. The 20 amp size breaker is used for dedicated appliance receptacles, hot water tank and baseboard heating. The 30 amp size breaker is used for a clothes dryer. The 40 amp size breaker is used for the electric range.
Add up your amps to calculate your breaker size. Add up your loads (amps), divide by 0.8, and choose that size breaker. If that number does not correspond to a standard size breaker you go to the next higher standard size breaker.
Read the literature for the ac condensing unit, or the tag on the outside of the unit. Minimum circuit ampacity= minimum breaker, wire and fuse size. Maximum circuit ampacity= the maximum size. Your circuit breaker, wire size and disconnect fuses should all be at or between those 2 numbers.