I have noticed from several videos and now i have an evidence from a video of a member here, that several 250W-400W MH lamps have outside Israel, much shorter cooling down period that in Israel.
Lets take for example this video: http://www.lighting-gallery.net/gallery/displayimage.php?pos=-64303.
The Philips HPI-T 250W in this video, takes only 2 mins to hot restrike with the fixtures original ignitor. The same lamp (HPI-T) but the 400W version in a Gaash Jupiter floodlight on the building of Ein-Hayam elementray school, observed by me hot restriking after 15-20 mins with an Eltam ES50 semi-parallel ignitor, which produces 2-4 pulses/sec (Ash even went so far, saying that he saw an HPI-T that took about a hour to hot restrike).
The Osram HQI-T 250W/D in this video, takes 5 mins to hot restrike with the lantern original ignitor. The Osram HQI-E 150W/WDL in Park Hecht , for comparision, took twice (10 mins) to hot restrike.
Two other lamps, that i saw that takes 15-20 mins to hot restrike, are the Tungsram HgMIF 400/Dx and the US Osram Powerstar HQI-T 400W/N/SI when they hot restrike with the Eltam ES50 ignitor on Gaash transparent high bays in Leo-Beack high school.
Generally, most medium wattage (250-400W) MH lamps in Israel, tends to have a very long cooling down period with our local made ignitors or with the ignitors that available here in Israel.
Why this is happening??? Is there are problems with our local made ignitors?

I have a _guess_ :

The nominal voltage here is cited as 230V and thats what the ballasts are rated for. At least here, it is usually around 240V or higher (at my home it can be as high as 245). The lamp may be overpowered and overheated in the 1st place, then it takes long time to cool down

I dont think it have anything to do with ignitors - i seen this happen with both semiparallel and superimposed ignitors, both in locally made and imported fixtures (such as Gaash Jupiter, Lanzini Raggio2, and others)

Ash: My wondering is regarding to lamps that i saw their hot restrike both on videos and in reality. I don't understand why in Israel the Philips HPI-T 400W takes >15 mins to hot restrike while the Philips HPI-T 250W of lantern_vision managed to hot restrike within 2 mins, which is the same cooling down period of the MV lamps.
I think that i even seen a video of lantern_vision of his 1000W HPI-T restriking in a very short time.
And regarding to the actual voltage: My Advice PRD650 UPS shows the actual input voltage, and it is usually around 230V and not around 240V.

dor, 15 minutes is too long, also for an ceramic metal halide.

Are you sure your ignitor is fine?

 I used to have a junk regent yard light that is metal halide. it only 70 watts but it took 25 mins to resrike
within one month of use the igniter fail. never going back to MH again.

dor, 15 minutes is too long, also for an ceramic metal halide.

Are you sure your ignitor is fine?

marcopete: This is what I think. Also, all of the MH lamps that I saw that tooks 15-20 mins to hot restrike, used semi-parallel Eltam ES50 ignitors that produces 2-4 pulses/min (The lamp strobes during hot restrike, and the ignitors clicks instead of buzzing). However since Ash encountered with MH lamps with very long cooling down period, also with superimposed ignitors. I think that there are problems with Eltam ignitors.
It is also possible that the ignitors in the fixtures that I saw with their lamps hot restriking, the ignitor probably was weak.
The Osram HQI-T 150W/WDL in one of the AEC Serikas in Park Hecht, hot restriked during cycling within 10 mins with its original superimposed ignitor of the lantern. If this cooling down period should be shorter, so there are problems with the ignitor in that fixture.

dor, what about line voltage?
Are there brownouts?

We have sometimes power failures that causes the road lanterns to go out for a short time.
The 15-20 mins hot restrike of the Philips HPI-T in a Gaash made floodlight with an Eltam ES50 semi-parallel ignitor, that lies on the building of Ein-Hayam elementary school, was seen only during brownouts.
The 15-20 mins hot restrike of the Tungsram HgMIF 400/D and the US Osram Powerstar HQI-T 400W/NDL in Gaash made transparent highbays that lies inside Leo-Beack high school, that also used Eltam ES50 semi-parallel ignitors, was seen also only during power interruptions.
Lamps that hot restrikes on an Eltam ES50 semi-parallel ignitor, don't exhibits a continuous sparks, arcs or glow, like most ignitors outside Israel, but instead, the lamps strobes 2-4 times/mins, similar to a xenon flash tube.

I am quite sure it have nothing to do with ignitors or brands. It looks like overheated/overpowered lamps to me that take too long time to cool down

The only way of finding that out for sure would be to buy a British 240V ballast and a 230V ballast and run identical lamps with both, using the same type of ignitor, to compare hot re-strike times.

Would be a useful experiment

Out of interest I just stuck a meter in one of the sockets and it measured spot-on 240V.



BG