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G6Tanuki · 11th Jun 2019, 5:15 pm

I can sort-of see the logic of 2 120V bulbs in series, but from an economic perspective I kinda wonder.

2 new identical bulbs in series - apart from the 'infant mortality' failures (where a component fails in the first few hours/days of its life usually due to a manufacturing defect or trauma during installation) I would expect two identical series-connected bulbs to age-to-failure at about the same rate.

So both the reliability-engineer and the economist in me would say 'when one in the pair fails, replace both' on the basis that the surviving one will probably also fail in the near-future, fitting two new bulbs gives a guaranteed future life (infant-mortality excepted), and the cost of sending the guy-with-a-cherry-picker out again a few days later is going to be significantly greater than the cost of fitting two new bulbs in the first place.

I apply the same economic logic to replacing scale-lamp bulbs in radios: bulbs are cheap, my time is valuable (and becomes significantly more-valuable to me as I get older and my remaining years get less and less).

11th Jun 2019, 5:15 pm	#60
G6Tanuki Dekatron Join Date: Apr 2012 Location: Wiltshire, UK. Posts: 13,998	Re: The lightbulb conspiracy I can sort-of see the logic of 2 120V bulbs in series, but from an economic perspective I kinda wonder. 2 new identical bulbs in series - apart from the 'infant mortality' failures (where a component fails in the first few hours/days of its life usually due to a manufacturing defect or trauma during installation) I would expect two identical series-connected bulbs to age-to-failure at about the same rate. So both the reliability-engineer and the economist in me would say 'when one in the pair fails, replace both' on the basis that the surviving one will probably also fail in the near-future, fitting two new bulbs gives a guaranteed future life (infant-mortality excepted), and the cost of sending the guy-with-a-cherry-picker out again a few days later is going to be significantly greater than the cost of fitting two new bulbs in the first place. I apply the same economic logic to replacing scale-lamp bulbs in radios: bulbs are cheap, my time is valuable (and becomes significantly more-valuable to me as I get older and my remaining years get less and less).