IEC 60192: Low-Pressure Sodium Lamps — The 200 lm/W Efficiency King

Low-Pressure Sodium Lamps — The Efficiency King (200 lm/W) Unique Position

IEC 60192:2001 specifies low-pressure sodium lamp (SOX) performance. SOX lamps hold the record for the highest luminous efficacy among practical light sources (~200 lm/W), but their monochromatic yellow emission (589 nm) means colour rendering index Ra = 0.