Would the replacement of regular toggle switch with a dimmer have any effect on energy savings? What I want to know is that, if I dimmed a 40W light bulb for about 3hrs compared to a switch that stays on for the same period of time, would the electric bill be the same? Thanks.
Depending on your rates, it might cost you a penny to run the 40W bulb for three hours. Put in a dimmer and you might save 1/4 of that. You might save 10 cents a month.
This is for a conventional filament lamp and nto an energy savings one:
A dimmed electric light will use more electricity than one that is off and less than one that is on full.
Le's say you are paying 10p per kWhour.
Your 40W bulb will use:
40 x3 x10/1000 or about 1.2p worth of electricity when full on for 3 hours.when dimmed, say:
20 x 3 x 10/1000 or about 0.6p of electricity for the same time.However, lamps are less efficient when they are dimmed - they give out correspondingly less light. You would be better fitting a 20W light bulb than running a 40W light bulb at half power.
But, a dimmed light bulb will probably last longer than one full on - particularly if the dimmer has a "soft-start".
To find your own costs, put in your own electricity unit price.
If a dimmer switch costs 10GBP, and you could happily run with the light dimmed for, say, 4 hours a day, then the switch would be paid for in electricity savings within 2 years..
At around one hour a day or less, it would take you heading towards 10 years to break even..
Fitting energy saving light bulbs would be better..
A common question is whether dimmers actually cut electrical use. Modern ones do! Very old resistance dimmers didn't (some folks still call dimmers "reostats".)
How much is variable as the other posters mentioned. Most dimmers drop the voltage slightly even when "full" on. There are lots of complex details....
A dimmer has one advantage over enery efficient or lower wattage lamps: You can easily change the brightness. If that is of value then the cost of the system is probably not significant.
RickR
Sorry, but this is not true. Reostats do reduce total power consumption, although not efficiently. Example: Bulb = 120 W @ 120V; I=1A: R=120Ohm Add 120 ohm resistor in series (set with the reostat): Total power: V^2/Rtot = 120x120/240= 60W! The bulb uses 30W and the reostat
30W, but the total power is half of the lamp used without reostat. You could do the generic algebric calculation and find a hyperbolic relation between total power (y-axis) and total resistance (x-axis).
I tried to keep it simple... ;- (
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