the resistance attributed to its short wiring lengths is negligible. Therefore, we will only be concerned with the resistance created by the three 30 ohm valves.
larger the diameter of the wire), the lower the resistance of the circuit. The reduction in resistance due to multiple wire paths, can be easily calculated, providing us an ‘expected’ resistance value. In the case of Circuit 2, three times more paths The parallel wiring configuavailable will create one-third the ration of this circuit will create an expected measured resistance of 10 resistance. Calculation wise, the expected resistance for a three valve ohms. What!!! …more solenoids and less resistance? That makes no (30 ohm each) circuit wired in a parsense! Well, yep, that’s correct. This allel configurations, calculates to 10 takes a bit of explaining, so hang-in ohms (30 ohms divided by three). Note: If the circuit situation conthere. tained two 30 ohm valves wired in parallel, we would expect the circuit We are measuring the resisresistance to be 15 ohms (30 ohms tance created in the circuit due to electrons “bumping” into each other divided by two). For a four valve circuit, we would expect 7.5 ohms and getting bottle-necked as its (30 ohms divided by four). travels from terminal to common. When valves (solenoids) are wired in parallel, the electrical path that Actual Observations & Readthe electrons take down the wire ings: have multiple paths to get from the (1) Whole System Observations: terminal, through the solenoids, and Since you are troubleshooting an back to the control circuit’s comirrigation system, take an initial mon terminal. Therefore, multiple look at the overall system… don’t paths for electron flow mean lower just jump to conclusions (make asresistance. Compared to Circuit 1sumptions) based upon previous site which only has one wire path for history or owner/operator advice. the electrons, Circuit 2 has three It is easy to take for granted that a wire paths. Therefore, the more wire system malfunction is due to equippaths available (and likewise, the ment. Quite often the malfunction is Page 34