 Some adapters for wall outlets use an Edison screw, allowing a light socket to become an ungrounded electrical outlet (such as to install Christmas lights temporarily via a porch light), or to make a pull-chain switch with two outlets, or to split it for two lamps.Another adapter can make a wall outlet into a lamp holder (lamp socket).Various other accessories have been made, including a smoke detector that recharges over a few hours and lasts for a few days or weeks thereafter, and still allows the attached lamp to operate normally.