Re: T8 Ballast

["S. Hieber" <shieber at yahoo_com>]

Victor Eng said:

> The T-8 ballasts at Home Depot are 0.90 ballast factor
> while these ones are
> 1.3 ballast factor which makes it more efficient (not
> energywise, but output
> wise) and more expensive.
> 
> Ballast factor is a measure of the actual lumen output
> for a specific
> lamp-ballast system relative to the rated lumen output
> measured with a
> reference ballast.
> 
> So the higher the  ballast factor the more lumens will be
> output.

Pardon my being persnickity -- I think you meant to say
"effectiveness" rather than "efficiency."  Ballast factor
says nothing about efficiency, you need to divide the
lumens (or other measure of light output) by the input
watts to determine efficiency.  Just because it's called
4x32 ballast doesn't mean it uses 128 watts -- could use
considerably more or less, and may or may not
over/underdrive a given type of lamp.

The ballast factor is relative to a specific bulb compared
to standard ballast, as you point out.  But that means
that, if you change bulbs, then the ballast factor can
change, especially with some electronic ballasts that adapt
their output under different loads.

Wayne has collected some interesting test data on the
ballast with different bulb combos.

Scott H.

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