Hi! I recently just accquired 5 sox bulbs. One 18w Two 35w One 55w and A 90w. I currently have two ballasts. A Fulham WH3 and a Fulham WH5 what are the best ways to wire the ballasts for all these bulbs? How many wires should I use. So far I use the WH3 with both reds for the 18w. Also, would a WH2 be better for the 18w bulb? From what I read I can power the 90w with 4 reds on the WH5. Any advice for twisting all 4 wires together? They are very stiff.

I haven’t tried a wh2, if you do I would make sure it lands about 19/20w of power when warmed up fully if you do. Otherwise the lamp would be under run. A wh3 seems to run either an 18w or 35w lamp with no issues on two reds in my experience.

If you want to find out where the 90w lands I would use a kilawat or similar meter to find out the input power to the ballast as you try different numbers of wires. It’s good to start with a lower number and work your way up to avoid overdriving the lamp. Keep in mind that on a workhorse ballast at least the lamp will draw a much higher power during warm up than when it is at full temperature. Input Power will usually rise at first, crest, then slowly fall when sodium starts to join the discharge to rated power at full temperature. If you go past 20-25 minutes and the lamp still hasn’t full output power or there is still neon in the discharge then it is probably going to need another red wire. Also, a new lamp usually takes much longer to warm up than one that is used since the sodium hasn’t had a chance to be distributed in the arc tube yet. I have especially noticed this with the larger wattages as my 180w took almost 45 minutes to warm up the first time I struck it.

When it comes to commoning the wires I would either get them all straightened out and hold them while attaching a wire nut or wrap some e-tape around the bundle to hold it for you so you can get a wire but on them.

Good luck!