No The Canadian Code and NEC specifically state extension cords shall not be used as a substitute for permanent electrical premise wiring. This method, is not code compliant, as the extension cord is physically attached permanently to the ROMEX inside a junction box, making it a fixed wire connection, not temporary or removable. Only two solutions exist for concealed power wiring to a wall mounted TV or ceiling mounted projector. 1) Install a standard A/C outlet wired directly to the premise circuit. 2) Install a PowerBridge In-Wall Power Extension with in-wall power-wire rated for your area, safest and easiest and code compliant method of concealing power inside walls.