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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.
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SteveIt is not recommended to use a 40 amp breaker to feed a sub panel, as the breaker size should be based on the size of the wire and the load of the sub panel. It is important to follow the manufacturer's guidelines and local electrical codes when determining the appropriate breaker size for a sub panel.
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What would happen if a 200 amp breaker is used in a 100 amp sub panel?
There are two things to think about here. First of all a 200 amp breaker will not physically fit into a 100 amp panel. This is so designed because the panel buss is not designed to conduct 200 amps before the current is cut off. A 100 amp rating on the panel is the maximum amount of current that the manufacturer states, that can be handled safely. Second if the 200 amp breaker is in the main panel then everything downstream from that breaker has to be rated for 200 amp conductivity. The wire size will have to be 3/0 from the breaker to the first over current device in the sub panel which will be the sub panel's main breaker. The sub panel can not be a load center but will have to be a combination panel. I doubt that the 100 amp sub panel's main breaker lugs would be large enough to connect the 3/0 cable.
Can you feed a 60 amp sub panel from another 60 amp sub panel?
Yes, you can feed a 60 amp sub panel from another 60 amp sub panel as long as the total connected load does not exceed 60 amps. Make sure to properly size the wire and protect the circuits with appropriate breakers to ensure safe operation of the sub panel.
Can you had a 20 amp breaker on your 70 amp sub-panel that has already 70 amp total on it that consist of one 50 and two 15 amp breakers and the panel has 4 available spaces out of 8?
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Can a sub panel from a 15 amp breaker be used with a branch circuit with 20 amp breaker?
Answer for USA, Canada and countries running a 60 Hz power supply service. Yes you can add these two breakers to the sub panel. You will have to keep in mind the fact that if the total loading of the two breakers exceeds 30 amps the 30 amp sub panel breaker will trip. If you use the 20 amp and the 15 amp loads individually then you will be under the 30 amp feeder sub panel breaker and good to go. With feeders of 3 conductor #8 the 30 amp breaker can be increased to 40 amp. If there are large motor loads involved this answer will change as starting current has to be calculated into the equation. View discussion page for additional information.SAFETY ADVICE Before you do any work yourself,on electrical circuits, equipment or appliances,always use a test meter to ensure the circuit is, in fact, de-energizedIF YOU ARE NOT REALLY SURE YOU CAN DO THIS JOBSAFELY AND COMPETENTLYREFER THIS WORK TO QUALIFIED PROFESSIONALS.
Can a 60 amp main breaker be used to supply a 100 amp subpanel power so that I can take advantage of the extra curcits provided by the larger panel I'll only be using 45 amp at any time?
It is not recommended to use a 60 amp main breaker to supply a 100 amp subpanel. This can lead to overloading the main breaker and potentially causing a fire hazard. It's important to match the ampacity of the subpanel to the main breaker for safe and efficient operation.
