Motor Starters vs. Breakers/contactors


Thread Starter


In a lot of the machines I work on, I only see a breaker connected to a contactor which is connected to the motor. I don't see any thermal overload relays or motor starter components. Why not? Is the thermal overload not needed or is it integrated in the breaker/contactor?
Don't know what "breakers" you're seeing, but they may actually be manual starters and thus include overload protection.

Doing this with a contactor and no other overcurrent or overload protection is called a "group motor application" and is allowed for certain size panels, if the specific manual starter and contactor are approved for use in that application.

This is a popular thing to do in OEM equipment, so the standard contactors and manual starters from most brands have been tested and approved to use this way. But, there's no percentage for Siemens to pay to have their contactor tested and approved for use in combination with an AB manual starter, so in practice this means you have to purchase contactor and starter of the same brand (and check to make sure they're approved for that service).
the breaker can do the thermal overload functions like over current and so on. some application don't need a starter specially small motor in basic applications.
Look up section 430 in the NEC. It also covers requirements for over current protection vs. overload protection.