Replacement Bulbs Plug In NP7 Published February 1, 2017 at 300 × 300 in Replacement Bulbs Plug In NP7 This NP7 replacement bulb is 15 watts and should be used for plug in tart burners that have the SKU starting with CWPI. These bulbs warm up the wax melts which causes them to liquefy releasing the fragrance into the room.