of least resistance. More accurately stated, the majority of electricity will follow the path of least resistance. The actual distribution of the electrons is apportioned by the inherent resistance of any path it has available to it. A visual example of this is a lightning bolt that ‘forks’. The majority of electrons follow the least path of resistance, visually represented by the main bolt. However, there may be other higher resistant paths available to follow, and an apportioned percentage of electrons will take the alternate paths- thus visually creating a “forked” lightning bolt. This aware-
ness of potential multiple wire paths will become useful later in this and other articles. Shorted wire circuits: Short circuits are exactly what the name implies; the wire path is shorter than what was intended. Short circuit faults can be caused by many factors, with the most common being: damage to control wires from poor installation techniques (excessive pulling, bending, or damaging of the wire’s protective covering); careless digging; “critter” nibbling of the wire insulation (both in the field wiring and within
(1) Irrigation valves should be wired in a parallel, not in a series configuration. Incorrectly wiring the circuit into a series configuration will increase the resistance of the circuit. Increased circuit resistance can easily create excessive load (amount of amps drawn) when activated and can potentially cause malfunctioning valves, blown fuses, and damage to the controller’s internal components or wiring. (2) The expected electrical performance of irrigation components may be obtained from its product performance sheets, an affixed label, by contacting your supplier, or through the component’s manufacturer. Controller output typically ranges from 19 to 27 volts AC. The amount of resistance created by a valve’s electric solenoid may be found by referencing the manufacturer’s product information or by direct measurement using a multimeter. A valve’s solenoid resistance is measured in “ohms”. Generally, most 24 volt AC irrigation solenoids have between 30 to 55 ohms resistance. However, you can more accurately troubleshoot by knowing the specific expected resistance for the valve’s solenoids being evaluated. Page 30