Lumen and luminous efficiency reduction of Philips TL-D SUPER-80 tubes

Apparent downgrades of lumen and efficacy data apply to very many lamps from the big manufacturers during recent years. Actually the lamps usually did not get worse, but the manufacturers were forced to declare their specs more honestly.

Years ago there was a tolerance of normally about +/- 10% allowed on lumens and +/- 5% on Watts. At the time those tolerances were introduced that was really necessary to accommodate manufacturing tolerances. For instance, if a few million 100W 230V incandescent lamps were measured some could be as low as 95W and some as high as 105W. Over time manufacturers increased their production capability and could then achieve eg 98-102W. Some statisticians then realised that they could increase their lumen claim above competitors by re-rating their lamps to a nominal of eg 102W, with actual spread being 100-104W. So still conforming with international safety standards. But they did not increase their claimed power because the tolerances allow this margin.

A similar tolerance exists for lumens, and some big manufacturers used this to begin artificially inflating their claims so as to look better than competition. This started the so-called Lumen War where all major manufacturers tried to increase their published specs as high as possible. The manufacturers with tighter production spreads could increase their claims the most. For instance, if a lamp claims 1000lm, this is permitted so long as the average of the production batch does not drop below 90%. So it was perfectly legal to make eg a 950lm lamp but claim 1000lm.

Then when it came to efficacy, no tolerances were formally agreed. Some manufacturers combined their allowed tolerances on both lumens and watts, which resulted in lm/W claims being even further from the reality. The situation became so bad by the mid 2000s that governments started taking action to clamp down on such deceptive marketing practices. For the first time, manufacturers had to demonstrate that not only did their production agree with allowed tolerances, but also that the declared values coincided with the actual production mean. Furthermore, a 10% tolerance was also formally introduced on efficacy claims to clamp down on the deceptive manufacturers who were claiming as much as 10 higher efficacy than they could actually achieve. This stopped the practice of claiming highest possible lumens combined with lowest possible watts.

The result has been a gradual climb-down in declared lumens, watts and efficacy figures even though in reality the actual lamp might not have changed at all.