Originally Posted by arnyk
Your authority for that rather exceptional claim?
The National Electrical Code® NEC® states:
NEC ARTICLE 400 Flexible Cords and Cables General 400.1 Scope.
This article covers general requirements, applications, and construction specifications for flexible cords and flexible cables.
400.8 Uses Not Permitted (ref. Extension Cord) Flexible cords and cables shall not be used for the following:
(1) As a substitute for the fixed wiring of a structure
(2) Where run through holes in walls, structural ceilings, suspended ceilings, dropped ceilings, or floors
(3) Where run through doorways, windows, or similar openings
(4) Where attached to building surfaces
(5) Where concealed by walls, floors, or ceilings or located above suspended or dropped ceilings