The Norman Lamps 50A19-47V-IF is a 50W, 47V A19 incandescent light bulb designed specifically for low-voltage electrical systems that operate at 47 volts. Fitted with a standard E26 medium screw base, it installs directly into any compatible 47V fixture without adapters or rewiring. The frosted glass envelope softens and diffuses the output of the incandescent filament, reducing visible glare and producing a smooth, even illumination well suited to interior applications where visual comfort matters.

Because this A19 incandescent lamp is engineered and rated for 47V operation, it falls outside the voltage range defined for general service lamps under U.S. Department of Energy efficiency regulations, making it DOE exempt. This means it remains a fully compliant and commercially available incandescent option for the specific low-voltage systems it serves. The relevant regulatory definition can be reviewed at the eCFR: https://www.ecfr.gov/current/title-10/chapter-II/subchapter-D/part-430/subpart-A/section-430.2

Measuring 4.10 inches in length and 2.38 inches in diameter, the 50A19-47V-IF conforms to the standard A19 form factor and fits fixtures designed for that bulb shape. It is dimmable, allowing compatibility with appropriate 47V dimming circuits for adjustable light levels. Rated for 2,500 average life hours, this incandescent lamp is sold individually and is intended as a direct replacement for 47V low-voltage systems requiring an A19 frosted bulb.

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),"

• 50W A19 incandescent lamp rated specifically for 47V low-voltage electrical systems — DOE exempt under U.S. efficiency regulations
• Frosted glass envelope diffuses incandescent light output for reduced glare and comfortable, even illumination
• E26 medium screw base for direct installation in standard 47V-compatible A19 fixtures — no adapter required
• Dimmable design compatible with appropriate 47V dimming circuits for adjustable light levels
• Standard A19 form factor: 4.10 in. length x 2.38 in. diameter — 2,500 average life hours
• Sold individually; designed as a direct replacement for 47V incandescent A19 frosted applications

Tags: 50 Watts, 47 Volts