Proximity sensors / neg output triggering a reverse polarity relay setup for high power motor

[MarkT]

@JCA34F

You need pullups to hold the input pin HIGH when the switch is off, otherwise it could "float" LOW and cause a false input. You COULD use the Arduino's built in pullups

Given there's going to be some cable runs around machinery with high current mains and DC motors I'd suggest using around 1k physical pull-ups to reduce the risk of noise pickup on the switch wiring.