Most HVACR designers have a "premium" quality motor specification for critical or severe applications. Mechanical features include totally enclosed, non-ventilated (TENV) or fan cooled (TEFC) construction, cast-iron frame and end bells, and minimum bearing life specs. Class F (155 degrees C) insulation with Class B (130 degrees C) design rise, EPACT efficiency, 1.15 service factor, compliance with NEMA MG1 Part 31 for VFD applications and testing to IEEE 112 are also common requirements.
But what do you do when faced with specifying motors for wet, corrosive, or other harsh environments? Is your standard motor specification adequate, or should you include more stringent requirements?