https://www.ebay.com/itm/192890456840

Will this RUN (more or less) correctly 18w SOX/SOX-E lamps with UK mains, and would you do it?

(Admin edit - Listing ended, moved to general discussion)

https://www.ebay.com/itm/192890456840

Will this RUN (more or less) correctly 18w SOX/SOX-E lamps with UK mains, and would you do it?

no, you need a older version.https://www.ebay.com/itm/Fulham-Workhorse-2-Versatile-Solid-State-Electronic-Ballast-WH2-120-C-13065/281312639640?epid=1904059164&hash=item417f8a3a98:g:LdkAAOSwR0JUNw2C

Older? WH2?? Can you explain?

If you want to run a 18W SOX correctly you can use a 20W fluorescent choke with a stater across the lamp (assuming you have 240V). You must use a switch start choke. The specs are pretty much identical:

[th]Lamp[/th]    [th]Volts[/th]    [th]Amps[/th]
20W Fluorescent	59	0,33
18W SOX	57	0,36

Some professional ballasts actually specified that you need to use a fluorescent starter to make it work.

Hope this helps!

An 18W SOX lamp actually needs to run at 55V 0.35A. Most of the fluorescent ballasts I've seen are 0.37A and nearer to 70V, which will overdrive the lamp, and the ballast will get very hot.

If that the case  a crappy American preheat ballast should work fine with the starter.  With the spec you gave
me here.   

On 120V 60Hz possibly, but the original question was would it work on 240V in the UK, and I haven't found anything close enough except the rather rare genuine 18W SOX ballasts, everything else I've tried overruns the lamp and the ballast gets hot enough to boil a kettle 

In my own experience I have used 20W chokes for 18W SOX and they work perfectly. When I did a test the values were a bit off on the account that I was using a 240V choke when the mains voltage is 250V. The choke did get a bit warm but nothing different from if it was running a fluro.

If that the case  a crappy American preheat ballast should work fine with the starter.  With the spec you gave
me here.   

For some reason when trying a 18w SOX lamp on a US 20w preheat choke, I was not able to get it running while using a starter. I also tried a SOX ignitor and it did not work either.

Many LG members are from the UK. For North American alternate LPS/SOX ballasting you can browse here, and particularly here.

On 230V: The F18T8 ballast choke should be OK (with the starter or a SOX ignitor; the F18T8 is 55V 0.37A as well, after all).

On 120V: The OCV of just a series choke (e.g. an F20T12) could be insufficient to provide enough current in the initial cold electrode glow mode to warm the electrodes up and so transition to the final arc mode. Maybe there are some ignitors able to boost the voltage, but definitely just a stsrter wont be enough.
The HF electronic ballasts are good enough, they do provide really substantial power even at the elevated load voltage to warm the electrodes up. Just need to deliver the correct power at full warmup (there the fluorescents are way more tolerant and many ballasts exploit that; SOX need pretty accurate power feed).