It still might be, but realistically your best bet is try a new bulb. Other lighting types cost more to run per given light output. Sodium 'bulbs' are a bargain with very long lives and the ultimate run cost saving. More mode rn lighting technologies don't touch sodium's energy efficiency. Ice cold white with a slight violet halo = mercury Pure yellow = low pressure sodium orangey/pink = high pressure sodium Decent quality white = HID
NT