pm215: (Default)

(no subject)

posted by [personal profile] pm215 at 10:07pm on 19/10/2005
If you need convincing, think about lights that don't have dimmer switches, and note that they burn out when being switched on much more often than they burn out in use.

I think this is a bogus argument. Lights burn out on startup because of the inrush current for a cold lightbulb. Unless you can show that a dimmer switch on maximum dim limits the current sufficiently to keep the inrush current from taking out the weak spot in the filament, you haven't proved that you get any fewer bulb-blows-at-switchon incidents with the start-dim strategy. (And the Internet Light Bulb Book reckons that even if you do keep the weak spot from blowing now, it's still weak and you can't prolong its life by very much.)

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gerald_duck: (duckling sideon)

(no subject)

posted by [personal profile] gerald_duck at 11:16pm on 19/10/2005
I=V/R. For the same resistance (which is true), a lower voltage means a lower inrush current.

Yes, if the filament has a weak spot, limiting the stress you put it under will only postpone the bulb blowing. However, always dimming the bulb up instead of switching it on abruptly will help prevent those weak spots developing in the first place.

As has been noted before, it's not a terribly major effect, but it's there. And we were only asked what the effect was, not how significant it was. (-8
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pm215: (Default)

(no subject)

posted by [personal profile] pm215 at 12:32am on 20/10/2005
I=V/R

Yes, but the key word is 'sufficiently'. Clearly the current goes down, but does it go down enough? Anyway, enough of this pointless pedantry :-)

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