I think he thought it would heat the fridge up, Jed.
Medical people aren't very good with numbers (pace Mills). . . .
Hmm . . . Well, it would heat it up, naturally. But the fact that the fridge was cold when you opened the door showed that the compressor was keeping up, and removing more heat than the bulb generated. The only problem, then, was the cost of running the 20 W bulb and removing the heat. That would be ~100 W continuous, 2.4 KWH per day, about $0.20 per day worst case.
If it was a novelty, I guess I would have checked to be sure the switch was working, too. No point in throwing away money.
- Jed
