Many jobs involving a single 90° bend are quite simple and require no advanced knowledge or expertise. A fundamental principle in all EMT Electrical Conduit installations is that the pipe should conform closely to the wall or ceiling finish surface. In other words, do not allow the raceway to take a shortcut through open space in a building interior. Nor, generally, should a diagonal route be taken even if that would reduce the amount of raceway and wire required.http://www.chinagipipe.com/emt-electrical-conduit/