[Al Skierkiewicz]

Jim et al,
Under robot rules..
<R70> 24 AWG or larger diameter wire must be used for:
 connecting sensors, switches, potentiometers, accelerometers, and other detection
devices
 connecting a vision system to Robot Controller inputs,
 extending the PWM cables,
 connecting small muffin fans,
 wiring LEDs

I believe that is the rule that is referenced by the sensor manual. That being said, I agree that protection with a 20 amp circuit breaker is contradictory in this case. However, this rule (partial) is a better way to protect #24 wiring to sensors...

<R55> All active circuit breaker / power distribution panel branch circuits shall be protected from
overload with an appropriate value auto resetting Snap Action circuit breaker from the Kit Of Parts.
 Power feeds to custom circuits and additional
electronics must be protected with a 20A circuit breaker.
In addition to the required branch power circuit breakers, smaller value fuses or breakers may be incorporated into custom circuits for additional protection.

When in doubt, add a smaller breaker on your custom circuit board in order to feed sensors with #24 wire.