D.C. Mun. Regs. tit. 25, r. 25-C504
When a swimming pool, spa pool, or sauna is open during periods of low natural illumination, artificial lighting shall be provided so that all areas of the pool, including the bottom main drains are visible.
Overhead or underwater lighting shall be provided to illuminate the pool and adjacent deck areas. Such lighting shall be installed in accordance with the National Fire Protection Association (NFPA 70) National Electrical Code (2014), as specified in Subsection 102.1(l)(7).
For outdoor pools, overhead lighting shall provide not less than three (3) foot-candles of illumination at the pool water surface and on adjacent deck areas. For indoor pools, overhead lighting shall provide not less than ten (10) foot-candles of illumination at the pool water surface.
Underwater lighting shall provide a minimum of eight (8) lumens per square foot of pool water surface area, except when overhead lighting provides not less than fifteen (15) foot-candles of illumination at the pool surface.
Aquatic facilities that operate during periods of low illumination shall be provided with sufficient emergency lighting to permit evacuation of the pool and to secure the area in the event of power failure. The emergency lighting intensity shall not be less than half (1/2) foot-candle.
Branch circuits that supply underwater lights operating at more than the Low Voltage Contact Limit as defined in NEC 680.2 shall be Ground-Fault Circuit Interrupter (GFCI) protected.
D.C. Mun. Regs. tit. 25, r. 25-C504