If you already have the ballast its pre-wired either for 120 or 240 so you dont really have a choice and if your only using one 120 is fine.
socialistpete Reviewed by socialistpete on . 1000w hps is 120 or 240? got a 1000w hps bulba nd ballast which is the better way to go 120 or 240? Rating: 5