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RE: Aquatic Plants Digest V3 #466
It looks like many of your questions have already been answered, so I'll
just add my 2 cents here and there.
> -----Original Message-----
> From: Aquatic-Plants-Owner at actwin_com
> [SMTP:Aquatic-Plants-Owner at actwin_com]
> Sent: Sunday, August 23, 1998 9:48 AM
> To: Aquatic-Plants at actwin_com
> Subject: Aquatic Plants Digest V3 #466
> 1. VHO (Ice Cap) ballasts use only 50% of their rated electricity
> comumption, vs. PC. So a 420 watt VHO system will consume around 210
> watts of electricity. (PC vendors however say that PC's cost less to
> run than VHO's of the same wattage).
[Wade] I _highly_ doubt that the Ice Cap ballasts use only 50% of their
rated consumption. From an engineering standpoint, that simply doesn't
make sense. The rated consumption means simply that. What they could
be referring to is that the elec. consumption of the system is less than
the nominal wattage of the lamps. For example, a typical two-lamp
electronic ballast for 32W T-8 lamps will use about 58 watts (with a
ballast factor of .88, which means it will output .88 times the rated
lumen output of the lamps). Why don't you check the Ice Cap website?
The only way that the PCs could cost less to run than VHOs with lamps of
the _same_ wattage is if they're comparing an electronic ballast and a
magnetic ballast. That is not to say, however, that a VHO lamp of X
watts will produce the same amount of light as a PC lamp of X watts.
Most likely they'll differ.
> 2. However, a PC system gives out twice the light (lumens) of a VHO.
> (Having just read the 'comments on lumens' in the latest Digest this
> appears to be completely irrelevant though). [Wade] If you're
> comparing lamps of the same type, say 5000 K, 85 CRI, one type of lamp
> may put out more light per watt than the other. However, the only way
> it's going to put out _twice_ as much light, given that they both run
> on the same type of ballast (electronic or magnetic) is that one will
> use about twice as many watts as the other. Some fluorescent lamp
> types _are_ more efficient than others (e.g. 32W T8's vs. 40W T12's),
> but they're not _that_ much more efficient.
> 3. VHO ballasts are very unreliable compared with PC units and will
> last as long. [Wade] Don't know about that.
> 4. VHO tubes last 6 months on average (although Champion Lighting
> they last 12 months) versus at least 14 months for PC's. [Wade] Don't
> know about this either.
One of my homemade systems which uses commonly available F40/30 "Biax"
lamps that run on "regular" electronic ballasts used for T8s has been
running for about 3 yrs. These lamps have a rated life of 20000 hrs, so
I've gotten more than that already. I'm cheap so I won't change them
until they're dead, but even then, they'll maintain over 85% of their
initial lumens throughout their life. The new GE lamps maintain 95% of
their initial lumens! BTW, Biax lamps look suspiciously similar to
"Power Compacts", although I think they put out less light and use less
electricity (5000K, 86 CRI, 2900 initial lumens and about 70W for two
lamps with a .9 ballast factor).