In article ,
J. Clarke wrote:
Lew Hodgett wrote:
"dpb" wrote:

No, I'm buying bulbs...or actually, not buying nearly as many bulbs
as would otherwise.

Actually you are buying both lamps and KWH to operate them.

If you wish to buy more KWH than are needed for the sake of
convenience, that's your choice.

If he's using 130v bulbs on 120v then he's using about 15% less KWH than he
would be using 120v of the same nominal wattage. If that gives him enough
light then he's got no problem. If he has to add bulbs or go up a wattage
level to get the illumination level he needs then things get more
complicated.



By using 130V bulbs on 120 V, he's paying *MORE*PER*LUMEN* for the electricity
to operate them, vs a 120V rated bulb.

Generally people thing of a light bulb as 'a light bulb', with little regard
to how much light it puts out. This leads to ill-informed decisions about the
cost-effectiveness of various alternatives.

The _first_ thing one has to do, is figure out how much _light_ is needed
and/or desirable, then look for the 'least cost' way of getting that amount
of light. Higher wattage bulbs produce more light output _per_watt_ than
low wattage ones. Thus, a few higher wattage bulbs will produce more light
than an equivalent wattage of low-wattage bulbs.

The true 'cost of ownership' of light bulbs depends on the cost of the
bulb, the frequency with which it has to be replaced, the 'cost' (labor,
etc) in performing the replacement, _and_ the 'operating cost' (the
electricity to drive it).

The cost of the electricity -- over the lifetime of the bulb -- generally
swamps the cost of the bulb itself.

The frequency of replacement determines how much of a factor the 'cost of
replacement' is. Depending on circumstances, this can be a 'small change'
item, or it can be far more than the bulb _and_ the electricity to run it.