Explain why the Electrical National code demands users to control a motors start/stop using normally open/close momentary push button switch?



In the UK any electric motor with a power output greater than 350 watts must be fitted with a device that will prevent re starting when the power is restored following a break in supply. It is normal to include this in the starter along with over current protection. Depending on the capacity of the supply, larger motors must have a method of limiting the starting current provided in the starter.


There is no such requirement that I know of. Motors can be controlled by any manual or automatic device, with third party listing (usually UL) as a motor operator and rated for the power of the motor. For most applications, a motor does require a local disconnect switch to assure the safety of someone who may be servicing the motor.


Cite the paragraph in the NFPA 70 book, there's over 800 pages. Using a momentary switch means there is a controller between the switch and the motor unless it's a safety limit switch. I've seen many motors controlled by simple switches.