Alright, so i checked out power consumption of my SOX 90w with BSX90 ballast. I am unsure of how the ballast exactly works, and how the internal windings are connected. Check out the picture of my ballast box.

Measured current with a non-true RMS multimeter is 540mA at 234v mains, so that indicates 126w.
With a plug-in wattmeter (Conrad EKM265, comparable to a Killawatt) it shows 109w.

If i can believe the wattmeter, the losses are fairly significant but still within an acceptable range.

thanks for providing the test results and technical information, @Laurens and @Medved and @RRK - very helpful in gauging the performance and efficiency of the Qianshun ballast.

so far, i am still VERY impressed with the 35W one i purchased.    i ran it for 12 hours yesterday and it was just barely warm to the touch afterwards. i also had a couple of voltage sags when my air conditioner started, enough to cause all my lamps to dim or flicker for a short amount of time, and the ballast re-struck the lamp instantly as expected, no "complaints" or issues.

i'll see how it holds up over time, and i have a Qianshun 18W SOX-E ballast arriving at my home tomorrow afternoon so i am looking forward to testing that one out as well.

assuming all is well with these ballasts over time, i will in the future consider a high recommendation of these ballasts to those of us looking for new, efficient gear to keep our SOX lamps running happily.

BTW - the magnetic ballast i have been comparing against is an Advance 71A0490 (photo attached). i have 5 of them and have been swapping between them for control purposes - all behave pretty much identically as they all have the same date code and were in more-or-less daily service at my workplace for the same amount of time (about 12 years). i've replaced the 14uF capacitors on 2 of them to bring them back within spec; the other 3 are doing fine. this ballast choice could explain why mine have higher losses - they're dual-purpose ballasts that can also run 55W lamps, so i imagine some compromises in efficiency were made to allow them to run both lamps.

Still I believe something is wrong with your magnetic ballast or meter. Ballast certainly lists 0.62A line current with 35W lamp on the nameplate, but you show 0.759A at close to nominal 123V on your watt-meter. PFC capacitor is bad? 

I also have the 35W QS ballast. However, the current is very low for a 35W lamp, about 320mA / 98V (measured with HF probe). You can also easily run the 18W lamp with the 35W ballast. The 18W lamp runs at effective 16W with this one. I don't have the 18W version, but I assume it's exactly the same.

Additional data point: my 18w SOX draws 29w at 240v using the same watt meter.
With a TRMS multimeter (different one than the conventional one at work!) the current is 154mA, indicating 37VA.
The efficiency of the SOX 18 is, in other words, quite bad. As far as i know this SOX fixture i have (The Philips Combi Pack thingie, forgot the model number) has a series choke style ballast.

Hello, I have had significant experience with the Glow Object electronic ballasts.  I have used all but the 36W ballast; converting Spauling 90, 135 and 180W fixtures plus building several fixtures using 18, 35, and 55W ballasts / lamps.  While they are labled for 220-240V, after talking to the owner of Glow Object, and testing them myself, they actually work fine from about 110-240V.  They were mislabled for the Asian and European markets but work fine in North AMerica at 120V.  The only issue I had was that they just make the required lamp voltage for 180W SOX.  Most of my 180W SOX worked fine but I did have one lamp that was brand new and had the "bright flashes of white" at the electrodes until the sodium cleared that area of the lamp.  This caused the ballast to go into proection mode.  The 135/180W ballast has a green LED for proper operation and a red LED for problems.  I simply pulled the power, gave it a few seconds, and powered it back up.  The lamp did settle down.  I will state that the measured lamp current with these ballasts was 345mA for the 18W, 610mA for the 35W, 590mA for the 55W (and a 55W can be used for the 35W lamp of course), 870mA for the 90W and 910mA for the 135/180W ballast.  I do also use Fulham fluorescent ballast for my conversions but I do prefer the Glow Object ballasts and highly recommend them.  I have not had one fail yet.  Final note, they only dissipate between 3 and 14 watts, depending upon size; the 135/180 ballast dissipating the most.  The 135/180W does get quite warm and I have considered a small fan but hav not yet done that.  Mounting it on the metal plate, with some heat sink compund in my Spauling fixtures keeps them within safe operating range.  Much cooler than the magnetic ballast even though I love using the magnetics.  In 120V land here, its a no brainer to use the Glow Object ballast. 

Can you describe the way you measured lamp current for your electronic ballasts? It is not easy to do precisely and meters capable of doing this at 30kHz are quite scarce and expensive!

 

Here is how I measured ballast-delivered lamp current and voltages:  I work for a large communications company.  Along with many other things, we produce high power radio frequency power amplifiers.  The switching power supplies we use, and in some cases build ourselves, switch at frequencies in excess of 100kHz.  Some of the supplies produce up to 400VDC.  Peak voltages are in the 2kV region.  As a result, we (not I) have developed a test bench that can accurately measure voltage and current including peak, RMS, and crest factor.  The ballasts chop at approximately 18kHz; some as high as 27 or 28kHz.  That is well within the ability of our test bench to measure the paramters.  I took ballasts and lamps in on a Saturday and did the measurements.  It is actually quite easy with the test bench; difficult as you know without specialized test equipment. 

@K9qi, do you have any information on what Workhorse ballast to use and how many red wires to run an 18W SOX lamp? Specifically, how many red wires do I use on the Workhorse 3 to power an 18W SOX lamp? It would also be nice to have the configurations for the other SOX lamps when running them on Workhorse ballasts.