Hello; after the 35W SOX lamp for my room, I have decided to replace it with a 18W SOX because the 35W lamp is too much brighter. There is a problem, On Internet It's impossible to find a 18W ballast neither electronic one... So I have this ballast in the picture; I know that never run a lamp on a different ballast but I think It's the only possible solution. If I read right, this Ballast works on lower current then a genuine 18W SOX ballast, in fact It's around 220mA? OK I know it isn't correct current but, it sufficient that the lamp turns on and works safety without heating too much!

Thank you!             

Leonardo.

Zar

It depends on what a side of pond your on.
18 watt sox ballast is pretty expensive
  But u want get it around 350 mA
   At 55 arc volt.   So i am thinking
 A common 14 to 20 watt preheat ballast
 And a FS 2 starter perallel with the lamp holder
  Should be enough ignition voltage to strike the
 Lamp.

Hello; after the 35W SOX lamp for my room, I have decided to replace it with a 18W SOX because the 35W lamp is too much brighter. There is a problem, On Internet It's impossible to find a 18W ballast neither electronic one... So I have this ballast in the picture; I know that never run a lamp on a different ballast but I think It's the only possible solution. If I read right, this Ballast works on lower current then a genuine 18W SOX ballast, in fact It's around 220mA? OK I know it isn't correct current but, it sufficient that the lamp turns on and works safety without heating too much!

Thank you!             

Leonardo.

fulham Workhorse 2 ballast will work just fine for that.

Hello; after the 35W SOX lamp for my room, I have decided to replace it with a 18W SOX because the 35W lamp is too much brighter. There is a problem, On Internet It's impossible to find a 18W ballast neither electronic one... So I have this ballast in the picture; I know that never run a lamp on a different ballast but I think It's the only possible solution. If I read right, this Ballast works on lower current then a genuine 18W SOX ballast, in fact It's around 220mA? OK I know it isn't correct current but, it sufficient that the lamp turns on and works safety without heating too much!

Thank you!             

Leonardo.

I don't see problem to use 20/18W T12/T8 fluorescent ballast for the 18W SOX lamp. You can even run it on an electronic ballast for 18W T8 lamps.

The problem is that I have looked everywhere for this 18W ballast... but I did't find anything (also because if I have to buy a 18W SOX ballast I only want a magnetic one). So I bought yesterday a chinese electronic ballast from Aliexpress: this is an electronic one and It can turn on 8-16W I guess T5/T8 fluorescent lamps  ; so I suppose it could be work to switch on a 18W SOX ballast...?

Thank you,

with regard.

The problem is that I have looked everywhere for this 18W ballast... but I did't find anything (also because if I have to buy a 18W SOX ballast I only want a magnetic one). So I bought yesterday a chinese electronic ballast from Aliexpress: this is an electronic one and It can turn on 8-16W I guess T5/T8 fluorescent lamps  ; so I suppose it could be work to switch on a 18W SOX ballast...?

Thank you,

with regard.

I'm affraid that ballast will operate at too low current (the SOX18 require 0.36A, which happens to match the F18T8/F20T12). But rhe lower power fluorescents are designed for lower current: F15T8 at 0.22A, F8T5 at 0.16A,... the fluorescents usually handle the mild undercurrent well (the F15T8 will run at about 10W on 0.16A), but the SOX wont be able to reach its working temperature.
So you really need a proper full power F18T8 ballast.
Other option could be to tie two "PL-S" ballasts (0.17A) in parallel (so to get about 0.34A), the PL-S ones use to be available more often, at least here...

For my outside light which has 18W SOX, the original magnetic ballast failed recently and I replaced it with a modern electronic ballast for CFL 18W lamps.  The CFL voltage is a bit different than the SOX but actually the ballast is doing a good job and runs the SOX lamp at about 16W.  The lamp probably runs a bit too cool and below its peak efficacy, but the high frequency of the ballast will help improve lamp efficacy somewhat.  I was surprised that the regular preheat-start ballast works just fine, the striking votlage of the 18W SOX lamps is so much lower than CFL that it works with only 2 wires connected to the ballast.

There are many electronic fluorescent ballast options that can drive LPS lamps. I like the Fulham Workhorse line myself. The outputs can be paralleled to adjust the output power slightly. I monitor the power draw on a watt meter, then add more of the red ballast output wires in parallel until the power draw exceeds the lamp power by ~10% (to account for ballast losses).

If you use this route, these links may be useful:
https://a89b8e4143ca50438f09-7c1706ba3fabeeda794725d88e4f5e57.ssl.cf2.rackcdn.com/spec_sheets/files/000/018/049/original/Fulham-Lamp-Chart-brochure.pdf?1442932828
http://site.electricsuppliesonline.com/images/fulham/Fulham-Wiring-Diagram.jpg

That's useful to know, James. I might try that sometime