12/2 wire with a 20 amp breaker for normal home wiring.
15 amp breaker.
AWG #10 copper on a 30 amp breaker.
The recommended amperage for a breaker to use with a 30 amp dryer is 30 amps.
The recommended amperage for a breaker to use with a range is typically 50 amps.
For a 41 amp load, you would typically use a 50 amp circuit breaker. The general rule is to select a breaker size that is 125% of the continuous load amps or equal to the load amps if it is not a continuous load. In this case, 41 amps is considered a continuous load, so you would round up to the nearest available breaker size, which is 50 amps.
For typical residential house wiring 12 AWG wire is required for a 20 Amp breaker. If you change out the breaker for a 25 A breaker you would have to rewire the circuit with 10 AWG. In that case you could up the breaker to 30 Amps. All outlets and switches should be rated at the same voltage and current as the breaker.
Breaker sizing is dependant on what the load amperage is that the breaker is connected to. If the amperage is not given but just the wattage, use this equation I = W/E. Amps = Watts/Volts. This air conditioner unit should be on a dedicated circuit receptacle. On these types of loads the conductor can only be loaded to 80% of the conductors rating. So a 15 amp breaker times 80% = 12 amps or Watts = Amps x Volts, 12 x 120 = 1440 watts. A 20 amp breaker times 80% = 16 amps or Watts = Amps x Volts, 16 x 120 = 1920. Once the breaker is sized remember to use the correct wire size to correspond with the amperage of the breaker.
No, it is not safe to use a #8 conductor on a 50 amp breaker. A #8 conductor is only rated at 45 amps capacity. By connecting it to a 50 amp breaker, which would trip at 50 amps on an overload, would overload the conductor by an extra 5 amps. This would be a conflict against the electrical code.
To determine the correct size breaker, you need to ensure that it is rated higher than the running amps of the unit. For a unit drawing 58 running amps, a breaker that is rated for at least 70 amps would be appropriate to provide a safety margin and prevent tripping due to overload.
Yes, you can use a 40 amp breaker to feed a sub panel. The wire from the 40 amp breaker must be #8 or larger. If you intend to use the full 40 amps a larger conductor must be used. Conductors can only be loaded to 80% capacity in continuous load conditions. A #8 wire is rated at 45 amps x 80% = 36 amps. The suggested size would be a #6 rated at 65 amps x 80% = 52 amps.
At 120 volts a 15 amp breaker can be loaded to 1800 watts before it will trip. If it is a continuous load then the electrical code states that it is only allowed to be loaded to 80%. This will be 1800 x .8 = 1440 watts. If the voltage is not 120 volts use the following equation Watts = Amps x Volts. Amps being the breaker size that is to be used.
A #12 copper conductor with an insulation factor of 90 degrees C is rated at 20 amps. A #14 conductor can not be connected to a 20 amp breaker as that conductor is only rated at 15 amps.