I’ve figured out the solution. What I needed to do was reference a particular object and set the trigger to work only when the integer associated with the object is greater than 0. You see, when a conductor is “powered up,” its “Lifetime” integer is set to a number higher than 0 and will not tick away as long as it’s touching other powered objects. So, as long as that last pipe’s Lifetime is 0, the trigger will not work. Anyway, thanks for your help and for your suggestion.