I have 3 rather large fixtures that say on one of the labels, Mercury Vapor and list it taking an H39 bulb. I actually used these last year for my first time shooting at night and they worked ok. They are quite heavy. I'm going to add them to my platform and wondered if I can put a 250 watt bulb in these?? They are a multi-tap ballast and current wired for 110v. The bulbs have a large base.
Pertaining to the 250 watt bulb question, what does this mean?
The last part says, "250 Watt max standby lamp can be connected to 120v for use when HID lamp is Off."
This is the part I don't understand.
Pertaining to the 250 watt bulb question, what does this mean?

The last part says, "250 Watt max standby lamp can be connected to 120v for use when HID lamp is Off."
This is the part I don't understand.