Amazon.com: Hoolerry Solid Sprinkler System Wire, 18 Gauge Irrigation Wire with UV Resistant PVC Jacket Sprinkler Cable for Underground Irrigation System, Field Central Control System 30V UL Listed (18/2, 50 Ft) :
Southwire 1-ft 18 / 10 Solid Sprinkler Wire (By-the-foot) in the Sprinkler Wire department at Lowes.com