Overcurrent protection for EVSE feeders must be not less than 125% of the maximum load.

Overcurrent protection for EVSE feeders must be not less than 125% of the maximum load.

• A. 200%
• B. 125%
• C. 150%
• D. 100%

Answer: (B)

The key idea is protecting a load that can run continuously. EVSE (electric vehicle supply equipment) can draw current for long periods while a car is charging, so the protective device must be sized with some extra headroom to handle that continuous operation and any small inrush when charging starts. You determine the feeder’s continuous or maximum load by adding up the maximum currents of all EVSE units that could be on that feeder. Then you multiply that total by 1.25 (125%) to get the minimum overcurrent protection rating. This extra 25% helps avoid nuisance tripping during normal operation and gives room for future growth or slight inrush. For example, if the feeder’s maximum continuous load is 40 A, you would select at least a 50 A protective device (40 A × 1.25). The other options would either undersize for a continuous load or provide more headroom than required, which isn’t necessary based on this rule.

The key idea is protecting a load that can run continuously. EVSE (electric vehicle supply equipment) can draw current for long periods while a car is charging, so the protective device must be sized with some extra headroom to handle that continuous operation and any small inrush when charging starts.

You determine the feeder’s continuous or maximum load by adding up the maximum currents of all EVSE units that could be on that feeder. Then you multiply that total by 1.25 (125%) to get the minimum overcurrent protection rating. This extra 25% helps avoid nuisance tripping during normal operation and gives room for future growth or slight inrush.

For example, if the feeder’s maximum continuous load is 40 A, you would select at least a 50 A protective device (40 A × 1.25). The other options would either undersize for a continuous load or provide more headroom than required, which isn’t necessary based on this rule.