Hello all,

So, i have a couple of fittings here that both use variants of the Thorn / GE 1000W CSI lamp, one being a sports spotlight fitting, the other being a Strand Patt 765 follow spot dating from the mid 1970's.

I have the starting gear for both fittings ( integral to their respective chassis) but i am short of a suitable choke ( and PF caps, but their easy to obtain)

Now, the arc voltage for the CSI lamp is somewhat lower than that of a typical MH lamp of the same power, hence the arc current is somewhat higher. 70-85V at 15A.

I can purchase a suitable choke, however it is a very expensive item as these lamps are now more or less obsolete, so the gear is getting that way too. I have many different chokes on the shelf ranging from 150W up to 1000W, all designed either for MH, MV or HPS use, my question is:

 If i were to combine chokes in parallel to achieve the arc current that the CSI lamp wants, what happens to the arc voltage and hence overall power?

Do i need to worry about AC waveform distortion or harmonics about using different spec chokes in parallel and how would you calculate the capacitance of the required PF capacitor?


I have read on here that someone used a 1000w and 400w choke in parallel to run a similar lamp so i think this may be a possible solution, however i really don't want to destroy the lamp

I guess i could try it with an ammeter and voltmeter in circuit but i'm sure their is a wealth of knowledge on here that has the answer already

Thanks in advance,
Chris