jgd@rsiatl.UUCP (John G. De Armond) (04/06/90)
jlg@lambda.UUCP (Jim Giles) writes: >In article <1990Apr4.174234.24288@tc.fluke.COM> inc@tc.fluke.COM (Gary Benson) writes: >> >> It costs more to turn lights off and on than to leave them turned on >> (regardless of the ratio of on to off time). >This is true for florescent lights. It requires an average of several >minutes worth of electricity to 'power-up' a florescent light. So, if >you're not planning to leave it off for a larger time that that, leave >it on. Incandescent bulbs should be turned off when they're not in use >no matter how short the interval till the are needed next. Actually no. This issue came up a few months ago and when the disucssion reached mythalogical proportions, I decided to make some measurements using a laboratory precision watt-hour meter. I measured the total power consumed from the instant of power application to the instant the bulb reaches full intensity and calculated a smoothed rate. I then compared that rate to the steady state consumption rate. I measured what was available in my lab which included a 20 watt old-style starter lamp, a dual tube 40 watt shop lite and a dual tube 100 watt industrial fixture. The latter 2 are both cold cathode, "instant on" types. The 100 watt lamp contains a "high power factor" ballast. For the instant-on lamps, the power consumption is actually lower than in steady-state. It is true that the lamp draws more AMPS but this is wattless current due to the low power factor of the unloaded ballast. The old-style starter lamp drew marginally (~15%) more power starting than during steady-state. Nontheless, the TOTAL power consumed during starting is equal to about 5 to 10 seconds of steady-state operation. The above isNOT to say that leaving lights on does not have merit. With flourosenct as well as filament lamps, the major consumption of internal resources occurs during powerup. In the case of filament lamps, a FAR greater factor in life is the applied voltage. A few volts higher than rating will completely swamp any variations due to duty cycle. John -- John De Armond, WD4OQC | We can no more blame our loss of freedom on congress- Radiation Systems, Inc. | men than we can prostitution on pimps. Both simply Atlanta, Ga | provide broker services for their customers. emory!rsiatl!jgd | - Dr. W Williams | **I am the NRA**