Voltage: 47V, Wattage: 50W, Type: A19 Light Bulb, Length: 4.10 in., Diameter: 2.38 in., Base Type: E26 (medium screw base), Life Hours: 2,500, Features: Frosted

These lamps are DOE exempt. 

The lamps are designed and operate at 47 volt. Therefore, they meet the requirement for the relevant exception.

The ruling:  https://www.ecfr.gov/current/title-10/chapter-II/subchapter-D/part-430/subpart-A/section-430.2

General service lamp

"means a lamp that has an ANSI base; is able to operate at a voltage of 12 volts or 24 volts, at or between 100 to 130 volts, at or between 220 to 240 volts, or of 277 volts for integrated lamps (as defined in this section),"