I’m getting 7 pcs of 90w sox lamps and i dont have ignitor for these. I only need one but i was thinking that would there be anything else way to start those lamps?  Here in Finland all sox light has been removed 10-15 years ago so it very hard to get gear for those.

Some have had success with the short-it-out method. Using a switch (or a very durable fluorescent starter) just short out the ballast momentarily to get the inductive flyback pulse, that should strike it. With the proper ballast of course.

Would 80w mercury ballast work? (230v) if doesnt then i might be bit screwd.

Ehh, I would say good enough for short term. My semi-accurate calculations predict ~16% underdrive. I am not familiar with how LPS tolerates underdrive so I have no idea if this is acceptable or not. Also the lamp might not stay struck, as 230VOC is kinda low for a 112V arc lamp, especially with something as high power factor as LPS.

If the ballast has different voltage taps on the input (220, 230, 240), use a lower one than normal to maybe get a little more current out of it. I don't think you will severely damage the lamp, but I don't guarantee it will actually work.

Edit: Nevermind, I just looked it up and it appears that ~230V choke ballasts do exist for LPS. It should stay struck just fine, just probably underdriven.

I made Some research and discovered that 90w lps runs on 112v and 80w me runs in 115v but a bit lower current than 90w Sox. 18w Sox start up very well with s10 starter and 18w t8 ballast.

Yup, so you should be good on from the OCV perspective, I am sure someone else can chime in later about the potential 16% underdrive and whether or not that is gonna cause a problem.

Thank you! I hope that somebody else would know something more.

I am sure someone else can chime in later about the potential 16% underdrive and whether or not that is gonna cause a problem.

A 16% underdrive will work for a short test, the lamp, run up fine, but if you plan to use the lamp, long term you, should stick to a less than 10% under or overdrive for your SOX lamp, or really any SOX lamp for that matter.

A useful way to finely adjust lamp current in 230V realm is to hook some low power fluorescent chokes (like 8W T5 or 11W PL which are almost equal) in parallel to main choke. If still not enough current, hook another one or upgrade say, to 30W choke

As for ignitor, 230V starter may work alone (or better in series with 100W lightbulb to make short circuit current reasonable). Or may not work with some hesitant LPS lamps which really need a dense series if ignition pulses to do glow-to-arc. In that case, assuming you have a pile of like LPS lamps and do not especially care for one of them, I'd just whack the lamp with some superimposed HID (MH/HPS) ignitor. Ignitor voltage will be somewhat high but outer volume of the lamp won't break down as it is hard vacuum. There is a remote chance of base flash-over, you have to look, but I believe ignitor voltage will be immediately clamped by arctube breakdown and lamp will light-up just OK.

Also, there are really heavy duty electronic ballasts having circa 800mA current, one probably will take a good care of such lamp, but these are quite rare, intended for equally rare high power CFLs.