Path: utzoo!dptcdc!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!rutgers!sunybcs!kitty!larry
From: larry@kitty.UUCP (Larry Lippman)
Newsgroups: sci.electronics
Subject: Re: fluorescent vs. incandescent
Summary: "starting" currents...
Keywords: none
Message-ID: <3098@kitty.UUCP>
Date: 17 Apr 89 04:43:04 GMT
References: <1369@hudson.acc.virginia.edu>
Distribution: usa
Organization: Recognition Research Corp., Clarence, NY
Lines: 45

In article <1369@hudson.acc.virginia.edu>, smf7s@hudson.acc.virginia.edu (friedman steven michael) writes:
> 	I know that fluorescent lights are more efficient than
> incandescent lights, but use a lot of power during start-up; whereas
> it costs nothing to flip an incandescent bulb on and off, but is more
> expensive to run over time.

	The "starting" current of a fluorescent fixture is NOT significantly
more than its operating current, and in some fluorescent lamps the starting
current is in fact LESS than the operating current.

	Even in a simple "preheat" circuit with a manual starting switch -
like a desk lamp - the filament current is of the same magnitude as the
ionized lamp current.  Fluorescent fixtures with preheat circuits using
starters usually fire the lamps in 1 to 2 seconds, and during the starting
interval the fixture current does not result in any significant excursion
above operating current.

	Fluorescent fixtures with "rapid-start" circuits (probably the
most common circuit in use today in North America) have a starting current
that is LESS than the operating current, since the filaments remain on
at ALL times.

	Fluorescent fixtures with "instant-start", "trigger-start" and
cold-cathode circuits have about the same starting as operating currents.

	On the other hand, incandescent lamps ALWAYS have an inrush
current that is MUCH higher than operating current since the resistance
of an incandescent lamp filament is MUCH higher when hot than when cold.

	Sorry, but that's just the way it is.
 
> My question is where do the efficiency curves meet?

	They don't.

> That is, how long does one need to keep a light on
> continuously before it becomes more efficient to switch from
> incandescent to fluorescent?

	Sorry, but this is a non sequitor.

<>  Larry Lippman @ Recognition Research Corp. - Uniquex Corp. - Viatran Corp.
<>  UUCP:  {allegra|ames|boulder|decvax|rutgers|watmath}!sunybcs!kitty!larry
<>  VOICE: 716/688-1231, 716/773-1700        {att|hplabs|utzoo}!/
<>  FAX:   716/741-9635, 716/773-2488      "Have you hugged your cat today?"