[Shop-talk] 220V extension cord with breaker

[cavanadd at frontier.com (David C.)]

Depends on how you define "circuit breaker" and "stationary power tool". 
  I have seen a lot of stationary tool motors (always single phase) that 
have thermal overloads built into them.  Motor gets hot, switch opens. 
Motor cools off, it closes, motor starts again (if it's on a manual 
switch).  Then again, I've seen a lot that don't have any overcurrenet 
protection built in, either.  Delta R/I motors installed in vintage 
Unisaws and other commercial/industrial woodworking equipment come to 
mind.

Motor starters, on the other hand usually always have overload 
protection of some kind built in.  They are built to sense overcurrent 
(usually by thermal means) and will shut the motor down, where it will 
remain shut down until manually reset.

Ronnie Day wrote:
> AFAIK, all motors in stationary power tools have built-in circuit
> breakers in any case.