I need to communicate hundreds of feet to multiple points at a tree nursery and wonder if Romex 14 ga non twisted pairs can be used. What MOV and Ferrite RIng devices could be used to protect against induced voltages from lightning? Other conductors in the same bundles are carrying 120 vac and 24vac for solenoid valves and to power microprocessors serving pressure and flow sensors. .
RS-485 is a balanced, differential signal. Over that kind of distance you are going to want to use shielded twisted pair for that.
They make RS-485 systems with built in Surge Suppression, for examples:
RS-485 options with built in Surge Supression
As far as lightning suppression in your overall system we don’t carry them but they make irrigation soleniod controllers with decoders that have built in lightning protection, you may want to talk to somebody that specializes in outdoor agricultural installations.