Re: low voltage & bulb species

From: Mike Lorrey (
Date: Fri Jul 06 2001 - 07:18:03 MDT

Damien Broderick wrote:
> At 07:37 PM 7/5/01 -0700, Spike wrote:
> >> incandescent bulbs produce about half
> >> their normal
> >> illumination that low (and if they are 130 volt long life bulbs, they
> >> will be even less bright), while still using 91% of the energy, which
> >> will prompt people to have more lights running at the same time to keep
> >> up the same illumination, thus wasting 40% more energy.
> >it incentivizes her to replace her incandescent
> >bulbs with low power flourescent.
> I reveal my elementary ignorance: do fluoros work if you lower the voltage?
> I have a couple of dandy little long-life 15-watt lamps = 75 watt
> incandescent or maybe 100 watt, but they are explicitly said not to work
> with a standard light-dimmer rheostat.

Standard fluorescent lamps do not function at all at about 90 volts, and
very poorly at 100 volts (if the temp is below ~40 degrees, they won't
light at that voltage either.)

However, you CAN buy fluorescent fixtures that use electronic ballasts
that have dimming and low temperature capabilities. These are also the
most efficient units, as well. I recommend you shop for ballasts with
.99 power factors and <1% harmonic distortion, along with the dimming
and cold start capabilities. The .99 power factor means that 99% of the
energy is being used by the lamp (older magnetic ballasts had PFs
between .5-.65, which wasted 35-50% of the energy in the ballast), while
the <1% harmonic distortion means that that much energy is being wasted
in harmonic feedback through the neutral and ground lines of the
building circuit.

These sort of ballasts are typically a few bucks more than normal
electronic ballasts, and about twice as much as magnetic ballasts, but
the savings are much greater.

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