Hello,

I've been reading these forums for ages and have learnt a lot
And  have managed to run some interesting lamps of off substitute ballasts.

I have some eye 50w HPS lamps and cannot get a suitable ballast, how do I calculate
The required choke sizing from my lamp data? I'll be running 230v supply, 50hz.

I can fire it up with a 58w t8 ballast or a pair of parallel 28w t-8 ballasts but
They definately over or under power the lamp. One combo runs it just over 100w and the other at 44w, but the single 58w fluro ballast gets quiet hot for 44w at the lamp..

Any thoughts ou there,

Have a good one

Tim

Prescribed ballast impedance for 50W HPS is 246 Ohm at 220V. Will be slightly higher at 230V. Some matching widespread substitute may be a pair of 30W fluorescent ballasts (480 Ohm @220V) in parallel.

58W ballast is right 240 Ohm @220V, so is a close match too. Will run at *slightly* higher than intended fluorescent tube current, nothing serious, but keep an eye on cooling, do not put in a tight box for example!