Just thought ide mention this...The Lithonia 2x F96T12 striplights that Menards recently clearanced appears to underdrive the lamps considerably. I bought two of them, and both measured 104w-106w when operating full power 75w lamps, after installing 60w miser lamps the power still measured the same. 104w is only 52w per lamp assuming no ballast losses. I thought the lamps appeared quite dim to begin with, and the watt-meter just confirmed it. Ive always known the modern electronic T12HO's to run at a 20% reduction or so, but this is the first time ive seen standard normal output being underdriven like this. Dont use your vintage F96T12's in these fixtures!

Is there ballast factor rating printed on the ballast ?

only "high power factor" is printed, but who knows what the PF really is.

Power factor is not same as ballast factor

Power factor = actual power drawn from supply / apparent power drawn from supply

Ballast factor = actual power delivered to lamp / rated power

I also didnt know there was a difference between ballast factor and power factor. how do you measure ballast factor?

ballast factor is the measurement of lumen output of lamps on that ballast compared to the lumen output of those lamps on a reference ballast

power factor is basically just measuring how efficiently the lighting is applying the power it is using.


correct me if im wrong there....

appears to underdrive the lamps considerably.
 only 52w per lamp assuming no ballast losses.

If they have the same wiring as a F96 T8 electronic, maybe they could be wired for overdrive...
Giving 78 (or maybe 90w if its a good ballast) watts for 1 lamp (also assuming zero ballast losses). So could end up being a perfect match.

power factor is basically just measuring how efficiently the lighting is applying the power it is using

Power factor is how much power the ballast is actually using vs the load on the supply



For example :

You plug in an 1200W convection space heater, which is essentially a Steel wire with total resistance of 12 Ohm, assembled in a device that lets it heat up and dissipate this heat into the air

120V / 12 Ohm = 10A

120V * 10A = 1200W

The space heater uses 1200W of power, and draws 10A from the line



Now take a 220uF capacitor

Xc = 1 / ( 2pi f c ) = 1 / ( 2pi * 60Hz * 220uF ) = 12 Ohm

120V / 12 Ohm = 10A

120V * 10A = 1200W

Plug in the 220uF capacitor into 120V. Just the capacitor, with nothing else. It will pass 10A, but won't do anything with power (i.e. it won't heat up, converting electrical power to heat power)

The capacitor is drawing 10A, same as if it would be 1200W heater, but it does not actually use the power. It does not take the power and convert it to heat, light, mechanical work or anything like that. It does not get wasted to losses either. All it does is charge and discharge back into the line on every half cycle of the AC, 120 times/sec


So, is the capacitor actually drawing 1200W or not ?

If we measure the current, we see that there are 10A flowing. Apparently it looks like if 120V * 10A = 1200W load is connected and drawing power. This is Apparent power

 - The wiring, circuit breakers, and all that have to be sized to handle the 10A, because 10A really flow in the circuit



If we measure the power used (and not returned into the line), it is 0. This is the real power

 - The meter does not spin for the capacitor

 - The power plant's turbine load (so by extension, the fuel use. pollution etc) are not increased by the capacitor's presence



The relation between the power really used (real power) and the "would be" power that is calculated from the current x voltage (apparent power) is the power factor

For a resistor like the heater, the real power = apparent power, PF = 1

For the capacitor, the real power is 0, PF = 0

For something else, it is something inbetween



How efficiently the ballast uses the power (ie. the part delivered to the lamp vs. the part in the losses) is efficiency, this have nothing to do with power factor. There can be a combination of any efficiency with any power factor

also assuming zero ballast losses

In case of Electronic ballast driving a lamp rated for Magnetic ballast, this is allmost the case. There are ballast losses, but at high frequency less power is needed to get the same output from the lamp

So for example, a 40W lamp powered by say 36W at HF will be as bright as 40W lamp powered by 40W from magnetic ballast. This gives 4W of "hidden headroom" for ballast losses, bc/ for example if the HF ballast have 4W losses, the complete lamp+ballast system will use 40W and light like proper 40W. so it behaves as if the ballast indeed have no losses

Most Electronic ballasts are not quite that efficient but the difference amounts to single watts

These must be electronic, of course...

I'm curious how they'd fare with F72T12, 55 watt lamps?

I've seen replacement electronic F96T12 ballasts used, and running 60w cool whites they sure seemed brighter/nicer/no striations next to the old magnetic ones, though those ballasts may have their capacitors going.

The F40T12 version of such a ballast I'm using seems to run lamps fine.

Funny you mention the F72T12 55w, as a few nights after posting this I tried a PL-L 55w lamp on this ballast, and it actually worked very well, which I was surprised to find given the significant arc voltage difference of a 55w PL and an F96T12. I then began experimenting with nearly every fluorescent lamp I had lying around, it didnt like anything except the F54T5HO (54w) which is nearly identical electrically to the 55w PL lamp. Could these be mislabeled T5 ballasts? Have manufactures given up on producing legit T12 ballasts, so they just relabel whatever might be closest in wattage for use in T12 fixtures??? I know it sounds crazy, but these ballasts operate the PL and T5 better than the lamps theyre rated for. Regardless of the lamp combinations and types I experimented with this ballast would not exceed 52w per lamp. I tried an F48T12VHO (110w), and it just ran it at 52w, but stable....very odd

It also ran an F40T12 just fine too, did not like T8's.

Was the F40T12 decently bright?

Also, did you try a F72T12? 

Could these be mislabeled T5 ballasts? Have manufactures given up on producing legit T12 ballasts, so they just relabel whatever might be closest in wattage for use in T12 fixtures???

Dont know about this case, but i seen mislabeled 54W T5HO ballasts before. They are labeled for 54W T5HO but underdrive the lamps badly, could be 36W T8 or 28W T5 ballasts inside