What is the feeder demand in amps for a 3,000 sq-ft bank that is accessible to pedestrians? The bank has 30 feet of show window and a 5 hp 240V air conditioner. All lighting, including any show windows and signs, is continuous. The panel supplying the feeder is 120/240V 1-phase 3-wire.

What is the feeder demand in amps for a 3,000 sq-ft bank that is accessible to pedestrians? The bank has 30 feet of show window and a 5 hp 240V air conditioner. All lighting, including any show windows and signs, is continuous. The panel supplying the feeder is 120/240V 1-phase 3-wire.

• A. 95 A
• B. 101.25 A
• C. 121.75 A
• D. 125 A

Answer: (B)

Feeder demand is found by summing the connected loads with the appropriate demand factors, then converting that total from volt-amperes to amperes on the feeder voltage. For a bank, the lighting load is treated as a continuous load, so it gets a 125% factor, and you include the motor load from the 5 hp air conditioner as a separate load. Since the service is 120/240 V single‑phase, you convert all loads to VA and then divide by 240 V to get amperes. In this case, the interior lighting is calculated at the commercial lighting rate, and because the lighting runs continuously, you apply the continuous-load adjustment. The show window lighting is included in that lighting calculation. The 5 hp air conditioner contributes its motor load in VA as well. After applying the NEC demand-factor rules for this occupancy and summing the VA, the resulting feeder current comes out to about 101 A (roughly 101.25 A). That value aligns with the given correct choice, and it reflects using the proper continuous-load adjustment for lighting plus the motor load on a 240 V feeder. The other options would not reflect the combined effect of continuous lighting with the motor load under the applicable demand factors for a bank, so they fall short or exceed what the NEC loads would require for a 3,000 ft² bank with a 5 hp AC on a 120/240 V single‑phase feeder.

Feeder demand is found by summing the connected loads with the appropriate demand factors, then converting that total from volt-amperes to amperes on the feeder voltage. For a bank, the lighting load is treated as a continuous load, so it gets a 125% factor, and you include the motor load from the 5 hp air conditioner as a separate load. Since the service is 120/240 V single‑phase, you convert all loads to VA and then divide by 240 V to get amperes.

In this case, the interior lighting is calculated at the commercial lighting rate, and because the lighting runs continuously, you apply the continuous-load adjustment. The show window lighting is included in that lighting calculation. The 5 hp air conditioner contributes its motor load in VA as well. After applying the NEC demand-factor rules for this occupancy and summing the VA, the resulting feeder current comes out to about 101 A (roughly 101.25 A). That value aligns with the given correct choice, and it reflects using the proper continuous-load adjustment for lighting plus the motor load on a 240 V feeder.

The other options would not reflect the combined effect of continuous lighting with the motor load under the applicable demand factors for a bank, so they fall short or exceed what the NEC loads would require for a 3,000 ft² bank with a 5 hp AC on a 120/240 V single‑phase feeder.