A high quality should last 10s of thousands of hours.
If used within specifications, a single- PHASE AC motor is more likely to fail due to mechanical failure (e.g. bearings, start winding switches if fitted, start/ run capacitor failure), than actual winding electrical failure. As mechanical failures are possible in any type of motor, the life expectancy of single- phase motors properly used, is many, many years of service without any problem. The only single- phase motors in my life that have given problems are the little type typically used as fan motors, such as ventilation and extraction fans and portable cooling fans. Their typical failure is the drying out of lubrication for their bearings, which are usually of the self- lubricating sleeve type with oil supplied by an oiled pad surrounding the bearing. By dismantling them and adding oil to the pad and through the porous bearings, I have NEVER had one that did not then continue in service many more years. I did this to one just last week.. an extraction fan in a bathroom that had been in service for 26 years. I had to re- engineer the way the motor was held together, as the manufacturer never intended it should be opened. But having re- oiled it, it now runs sweetly once again. I expect it will now outlast me!
