Quote Originally Posted by Ulsterman View Post
The failure is usually caused by the switch never being used and then they stick down in the on position not the wire being broke ---------So when you release the machine off the switch it is stuck on the on position -so normally open would be a good idea ?
No that's unsafe and it's very common for a wire to break or come disconnected in which case the machine E-stops.
Doesn't matter if the switch is stuck after being tripped because E-stop is still affective it just means you have to find the faulty sticking switch which you would want to do anyway.

Regards the Limit over ride then I use Momentary button with Buzzer warning it's overridden.