I have a Sylvania Lumalux 250W high pressure sodium lamp, a 175W mercury vapor ballast and a BBQ igniter. Can the 250W HPS lamp can start on a 175W MV ballast (with the igniter  ) ?

Do you have a picture of the lamp? Generally it's not a very good idea to mismatch ballasts/lamps. It will shorten their life.

Hi Vince, yeah you will ruin your lamp with the higher voltage of the MV ballast,plus I don't think the BBQ lighter would start it,you would need an ignitor. You will have to find yourself a 250W HPS ballast to try your lamp.

BBQ igniters will sometimes start a HPS lamp on a mercury ballast, depending on the minimum starting voltage required by the arc tube. Normally arc tubes with slightly lower pressure will start easily, while others are impossible!

I powered up a 100 watt HPS lamp in a 175 watt MV ballast with BBQ ignitor, the video is in my youtube account

And I powered up a 100w HPS lamp on a 175w MH ballast also using a BBQ ignitor, it was a cycler on a HPS ballast but ran without cycling on the MH ballast and even seemed to be the right color!

It's interesting what will work & what won't work on the wrong ballast. I think it also depends on the condition of the individual lamp & ballast.

I played around with my 100w HPS ballast the other night and found it would not light up a 70w (pulse start) or 250w MH (probe start) lamp - in either case, the ignitor makes an unstable, thin arc between the main electrodes, but that is it. On a 400w MH lamp, I get absolutely nothing. Interestingly, that 400w MH won't fire on a 400w mercury ballast either...it really needs a metal halide ballast, and it's a brand new lamp, too.

However, I was able to fire up a 400w mercury lamp on the 100w HPS ballast...it ran up to about half brightness with normal color, and didn't cycle, and the ballast didn't get hot nor did the arc tube blacken at all from being underpowered.

A 175w mercury lamp will cycle on this ballast, though. An incandescent or CFL will work fine, but at much reduced efficiency (system using more power than it would without a ballast).

Best to use a lamp on the gear it was designed for, for sure....

Arcblue......regarding to firing up MH in MV ballast.....I've noticed it depends on the brand of the lamps and lamps itself too....

A Sylvania MH lamp is usually the hardest to fire up....I have tried many Sylvania MHs on MV ballasts, either they never fire up OR it takes a while for them to fire up...that's for both Pulse and Probe. Other brands are easier to fire up though. I have three 50 watt pulse start Sylvania MH lamps and NO 50 watt MH ballasts...so I tried them on 175 watt MV ballast and my 39 watt CMH electronic start ballast....only 1 of my 3 is less stubborn than others...the 2 will never fire up while 1 will struggle and sometimes  successfully fire up. But again, wrong ballast, not gonna work properly, I'm just speaking about firing up. So even same age lamps (same date) each are different.

I forgot about that....maybe I should have just let it sit there powered for a while and see if it would eventually strike. My Sylvania 250w on a proper 250w CWA MH ballast even takes a few seconds to strike....but my pulse start 70w GE Halarc is even worse, sometimes taking over a minute....but it always lights. The 70w Sylvania fires instantly though. HID lamps can be "tempermental." And they change color as they warm up (sorry just had to try the color thing

Another thing to consider. If you attempt to fire a 55v HPS on a HX (no cap) MV ballast, it is possible to overheat the ballast because the lower lamp voltage will cause the ballast to run at a higher current. A CW (with cap) may be more tolerant because the current is more consistent despite lamp voltage variance. Also, a 175w mercury lamp will cycle on a 70w or 100w HPS ballast because the current is enough to pressure up the lamp to exceed ballast voltage. A 400w mercury lamp will require more current than ballast has to reach enough pressure to cycle, therefore it may stay lit at lower brightness.