I've been playing with more 4-20mA stuff. I want to design my input section to be fairly "bullet proof", since the sensor I am using - I have no idea if it could fail and dump the full 24V supply through the item and into my receiver's front end.

Referencing the little diagram below, my receiver has a 200 ohm 1% resistor. I've rated it for 3 watts since 24v into 200 ohms yields 120mA, or 2.88 watts, so that item is safe enough even at full loop voltage.