Nicked Wires: Nicked wires can create three troublesome issues. (1) The waterproofing integrity of the wire’s insulation is compromised, thereby allowing infiltration of moisture and subsequent corrosion. The infiltrating moisture may also enter any wire connection. Any such infiltrating moisture will undesirably increase the ohms resistance of the wire and connections. (2) The nick will reduce the wire’s diameter and create a physical “roadblock’ for the electrons to work through, thereby causing increased resistance in the wire circuit. (3) The nicked wire may be exposed to the soil, causing the electrons to travel into the ground rather than back to the controller. This
“ground fault” condition will create very high resistance measurementswhich is a very strong indication of a ground fault condition. Ground faults diagnostics and locating is a somewhat in-depth topic that cannot be covered in the length available for this article, but will be one of the topics covered in future articles. This concludes the first part of this article. Next month’s part-two article concludes the review of faulted wire circuits and includes multivalve circuits. In addition, a brainteaser will be provided, allowing you the opportunity to apply your understanding of variations in multimeter measurements in distinguishing between the various types of faulted circuits presented.
The MGCSA thanks Andy Lindquist for his expertice and inight into electrical circutry. Andy owns and operates Links Systems Inc. and can be reached at alindquist@ linkssystemsinc.com. Page 39