what size feeder for 100 amp subpanel

In most cases, you'll need a feeder that is rated for 100 amps when adding a subpanel to your home or workplace. But how do you know what size feeder to use? The answer depends on the type of subpanel you're installing, the type of circuit breaker you use, and the distance between the main power source and the subpanel.

When selecting a feeder size for a 100 amp subpanel, it's important to note that the actual draw needed is slightly less than the 100 amp rating. Since most standard 120/240-volt residential circuits allow for an 80% load, the actual load draw is only 80 amps. That means you'll need a feeder size that can handle at least 80 amps, although it's generally recommended that you use a feeder rated for 100 amps in order to ensure that the subpanel has enough capacity for future additions.

If you're using a standard double-pole circuit breaker with a 20-amp rating, the feeder size needs to be 6 AWG, whereas if you're using a 30-amp circuit breaker, you'll need a feeder size of 4 AWG. Additionally, if the distance between the main power source and the subpanel is greater than 80 feet, you may need a larger feeder in order to minimize voltage drop. In these cases, consider using 8 AWG for a 20-amp breaker and 6 AWG for a 30-amp breaker.

When selecting a feeder size for a 100 amp subpanel, it's important to consider the type of subpanel, the type of circuit breaker used, and the distance between the main power source and the subpanel. The actual draw needed is slightly less than the 100 amp rating, so use a feeder rated for at least 80 amps. If the distance is greater than 80 feet, you may need to go up to 8 or 6 AWG depending on the circuit breaker rating. With the right size feeder, you can ensure that your 100 amp subpanel will have enough capacity for all your needs.

Sub Tapping Mike Holt S Forum