Hello, and thank you for your question.
This bulb must be ballasted, as is true of all HID lamps. The voltage of this lamp will be a function of the ballast, and not of the lamp itself. In regards to the socket, this lamp carries an E39 (Mogul) base, and will not fit into a E26 (Medium) socket. For further questions regarding compatible ballasts for this product, or on recommended ballast voltage, please contact our highly trained sales staff at 888-455-2800.
Thank you for shopping at Bulbs.com!
Answered on 12/14/2015 by Dan from Worcester, MA