small oil furnace circuti size

[mjmike]

For a commercial Reznor oil furnace, the MCA is 8A and MFA is 10A. Voltage is 120V. I believe there are 2 options for the circuit but wanted to confirm:

1. 20A breaker with local fused disconnect with 10A fuses.
2. 10A breaker with local thermal switch.

In general, I believe you can have the branch circuit be any amperage you want as long as the local fuse is not more than the nameplate MFA. Example: 35A MFA can have a 100A breaker and circuit as long as the local fusing is not more than 35A. correct?

 

[kwired]

For a commercial Reznor oil furnace, the MCA is 8A and MFA is 10A. Voltage is 120V. I believe there are 2 options for the circuit but wanted to confirm:

1. 20A breaker with local fused disconnect with 10A fuses.
2. 10A breaker with local thermal switch.

In general, I believe you can have the branch circuit be any amperage you want as long as the local fuse is not more than the nameplate MFA. Example: 35A MFA can have a 100A breaker and circuit as long as the local fusing is not more than 35A. correct?

Technically the 20 amp breaker to the 10 amp fuse is a feeder, from there to the unit is the branch circuit.

If this unit specifies a max overcurrent protection then you must use that amount as the maximum, if it specifies it must be a fuse then it must be a fuse, otherwise standard breakers start at 15 amps, standard fuse sizes do include 1, 3, 6, 10, and 601.

 

[mjmike]

Technically the 20 amp breaker to the 10 amp fuse is a feeder, from there to the unit is the branch circuit.

Yes, you are correct, it is a feeder.

If this unit specifies a max overcurrent protection then you must use that amount as the maximum

I understand that is the maximum, but can the maximum be located at the last overcurrent protection meaning the breaker can be higher as long as it is fused at the max? 15A starts the recognized breaker amperage.

 

[GoldDigger]

Yes.

 

[mjmike]

Thanks