A snap switch wired under the provisions of this exception and located within reach of earth, grade, conducting floors, or other conducting surfaces shall be provided with a faceplate of nonconducting, noncombustible material or shall be protected by a ground-fault circuit interrupter."
Often a wall receptacle from an upper floor can be used as a source for a new ceiling fixture below, but a switch loop must be run to a wall switch in addition to fishing the cable from the source.
This page offers some options for locating an electrical source for a new wall receptacle or a light fixture, and running the new cable required. To make this job easier, it’s best to have a second person at one end or the other of a new run, to sight the end of the fish tape and help guide cable. Also be sure to always turn off the affected circuits before working on household electricity.
The second most common type of switch found in residential buildings is a 3-way switch. These can be identified by three terminal screws and a forth, green screw for connecting a ground wire. A 3-way switch is used to control lights from two locations like at the top and bottom of a flight of stairs.