How many incandescent should I use? And what wattage?

Hello you need a lot more watts . If you don't know I show how to get the right wattage.

1st: R=U/I=125V/1.15A = 109 Ohm
2nd: P=U^2/R=(120V)^2/109Ohm = 132W
at 1st: U...burning voltage; I...burning current
at 2nd: U...main voltage (120V US, 230V Europe)

That is an easy way to make your own self-ballasted mercury.

So I hope to helped you

Michael

Thanks Lampenfreak! But I tried with the closest wattage (130W, then 135W) and it didn't work...

Since I live in Canada, we use 120V. Anyway I run it on an H39 ballast instead.

I run my 125w MV on a 100w H38 yard light ballast. A number of these, such as mine, actually run a 100w lamp at about 115w - in fact the replacement lamps by Regent even say "100w-125w mercury vapor." The lamp runs fine although is a little underdriven, arc tube is still perfectly clear and ballast runs cool and I have used it a lot.

True 125w ballasts are hard to find in North America but they do exist.