People here use the terms HPF and NPF a lot.  Why do you guys even care? Unless you're doing a commercial job where HPF is a requirement and billed for having a poor power factor, it doesn't make any difference.

This is explained in this article:
http://assets.sylvania.com/assets/documents/faq0002-0297.cfc31719-5074-4c45-93bf-21fcd56907dc.pdf

Interesting article.  I prefer HPF ballasts because they drive lamps at or closer to full power.  LPF and NPF ballasts that I have seen drive the lamp at less than full power and therefore at less brightness.  Yea, it may save a little power, but what good is that if it requires more lamps to do the same job?  LPF/NPF RS ballasts are fun because they will run a lamp near EOL and allow it to non violently rectify, prolonging its "life" substantially.  I have a few of them, but only for playing around with.  As yall know, I prefer preheat, which truly throws 40 watts at a 40 watt lamp.  Many older RS ballasts do also.
Do a side by side comparison between HPF and NPF/LPF ballasts and you will certainly see the HPF units drive the lamps at or close to full brightness.  Check out xmaslightguy's youtube video too and it is obvious.

Yep, even my electronic RS ballast drive 40 watt lamps at 40 watts! Same thing with the 34 watt lamps, runs them at 34 watts, instead of lower..

Interesting article.

 I prefer HPF ballasts because they drive lamps at or closer to full power.  LPF and NPF ballasts that I have seen drive the lamp at less than full power and therefore at less brightness.  Yea, it may save a little power, but what good is that if it requires more lamps to do the same job?  LPF/NPF RS ballasts are fun because they will run a lamp near EOL and allow it to non violently rectify, prolonging its "life" substantially.  I have a few of them, but only for playing around with.  As yall know, I prefer preheat, which truly throws 40 watts at a 40 watt lamp.  Many older RS ballasts do also.
Do a side by side comparison between HPF and NPF/LPF ballasts and you will certainly see the HPF units drive the lamps at or close to full brightness.  Check out xmaslightguy's youtube video too and it is obvious.

That article actually has a few errors. I should have posted this one instead. I find this one to be more accurate.
http://www.advance.philips.com/documents/uploads/literature/RT-8010-R03_ABC.pdf
Pages 6-7

It's the BF (ballast factor) that determines output, so referencing by power factor is incorrect as you can see from ballast data I got for a few models.

Advance REB-2P32-SC is a residential electronic ballast for T8. It's the same 88% output as the  commercial use version, but the power factor is 0.5, so its a NPF. The commercial version is >0.9+ PF

L-140F-TP is a preheat, power factor is 0.52, and output is 79%.
R-140-TP is a rapid start. 0.99 PF with 97% output.  
HB-234-TP is a "resi" magnetic ballast with 41% output on F40T12. 68% on F34T12.  

All else being equal, I have never been too concerned about power factor. It seems sometimes, though, that HPF ballasts are better built than NPF, since NPF are typically targeted at residential installations.

The biggest advantage of HPF, even for residential, is the operating current is lower (not wattage) so that existing wiring is under less load. Typically, HPF ballasts are brighter because most North American ballasts are for more than one lamp size and the cap keeps a more constant lamp current, whereas, a NPF ballast has to under-drive a larger lamp to properly run a smaller lamp.

Example: a typical NPF rapid start or PH for one 30/40w will drive the 30w near normal brightness while the 40w would be rather dim. A HPF version of the same size ballast will drive both lamps at nearly the same current. Interesting note: the older PH 40w single lamp NPF ballasts drove 40w at full output and would overheat and overdrive a 30w lamp, therefore, they were 40w only.

Of course, ballast factor is the true output rating and not all HPF ballasts are brighter than NPF. I've seen both residential and commercial HPF designed to run lamps at lower output for energy savings.

Yes I know this is an old topic, but it's still a valid one.

I always try to include a PFC capacitor in any installation, for completeness if nothing else. I build demonstration displays amongst other things, and I like them to look complete. The capacitor may not be strictly necessary, but I will always do my best to include one.

The PDF isn't exist anymore, but I think that in a rapid-start ballast, the power factor affects the lamp performance, since these ballasts uses the capacitor as the ballasting component. NPF rapid-start runs the lamp at reduced power, while HPF rapid-start, runs the lamp at full power.

Either HPF or LPF ballast could be made to drive the lamps at full power or at reduced power. There is no "electrical" relation. There is only the relation, that most ballasts intended for commercial use are both HPF and higher power, while ballasts intended for residential use are both LPF and lower power

In the 230V hemisphere there is no difference, since the capacitor is external to the ballast and serves only for the power factor correction

https://www.lighting-gallery.net/gallery/displayimage.php?album=2158&pos=36&pid=108745



In things i wire with a cable and plug, if there are capacitors, i disconnect them most of the time :

 - The capacitor can hold significant charge and give a shock from the plug pins (normally not dangerous shock, but still quite big one)

 - Contact between the plug (charged capacitor) and random electronic stuff on the workbench can destroy the stuff

 - Plugging the plug into a power strip causees arc of the capacitor inrush current. In many power strips the clearance between conductors is not good enough and this arc will turn into a flashover across the 230V supply

If there is concern with the current draw of the luminaire (using few luminaires on a branch circuit or on a long extension cable of thin gauge), then it's better to include the capacitor

Either HPF or LPF ballast could be made to drive the lamps at full power or at reduced power. There is no "electrical" relation. There is only the relation, that most ballasts intended for commercial use are both HPF and higher power, while ballasts intended for residential use are both LPF and lower power

In the 230V hemisphere there is no difference, since the capacitor is external to the ballast and serves only for the power factor correction

https://www.lighting-gallery.net/gallery/displayimage.php?album=2158&pos=36&pid=108745



In things i wire with a cable and plug, if there are capacitors, i disconnect them most of the time :

 - The capacitor can hold significant charge and give a shock from the plug pins (normally not dangerous shock, but still quite big one)

 - Contact between the plug (charged capacitor) and random electronic stuff on the workbench can destroy the stuff

 - Plugging the plug into a power strip causees arc of the capacitor inrush current. In many power strips the clearance between conductors is not good enough and this arc will turn into a flashover across the 230V supply

If there is concern with the current draw of the luminaire (using few luminaires on a branch circuit or on a long extension cable of thin gauge), then it's better to include the capacitor

You can always install a bleeder resistor... that is what I do if the capacitor does not already come with one...

You can always install a bleeder resistor... that is what I do if the capacitor does not already come with one...

All proper PFC capacitors have them fitted.