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Re: 40W Ballast for 18" VHO?

At 3:48 AM -0400 8/26/97, "James T Miller" <jmiller at ns_net> wrote:

>I'm assuming that an 18" VHO Flourescent which dissipates 40W is no
>different in input power (I/V) characteristics than a 4ft 40W flourescent.
>If this is so, then for the four 18" VHOs I'm planning to use I don't need
>some fancy ICECAP ballast but merely something adequate for four normal 4ft
>Am I missing something?  This is a LOT cheaper!

Yes, the curent will be the same but the voltage will be about 18/40 less.
An electronic ballast is a constant current AC power supply, so it will
adjust the voltage to whatever (with reason) the light needs to operate. A
magnetic ballast must be sized to the length of the light, as it does not
have a active regulation.

You could actually use a dual output electronic ballast with self start
(i.e. no filament wires or starters) and connect 2 18" bulbs in series to
each output. Just be advised if one bulb burns out, the other will not
light, so you'll have to play musical bulbs to troubleshoot. T8 and T12
bulbs have diffrent current requirements. You should check to see that your
VHO's current requirements match the ballast.

Check out http://www.graniger.com/ for electronic ballasts. A dual output
electronic ballast capable of driving 4 18" bulbs should be under $30.00.
The lamp and ballast manufacturers all have tech support lines that can
answer questions about current and voltage.