A branch circuit supplying fluorescent lamps in a sign must not be rated more than what amperage?

The correct answer is based on the National Electrical Code (NEC), which specifies that branch circuits supplying fluorescent lighting must be appropriately sized to ensure safety and efficiency. The first relevant standard pertains to the maximum amperage allowed for circuits designed primarily for lighting purposes, particularly those serving general applications, including signs with fluorescent lamps.

A branch circuit rated for 20 amps is an acceptable maximum for powering fluorescent lamps. This limit helps prevent overheating and potential damage to wiring and fixtures, while still providing sufficient power for typical fluorescent lighting applications. Additionally, circuits supplying fluorescent lamps are often subject to specific code requirements regarding overcurrent protection, which reinforces the need to adhere to this limit.

Choosing 15 amps might not provide adequate power for all lighting applications, particularly those with multiple lamps or higher wattage requirements, while ratings higher than 20 amps increase the risks associated with overheating and circuit overloads. Therefore, a 20-amp rating strikes a balance between ensuring enough capacity for operation while maintaining safety standards outlined in electrical codes.