Test results, the cathodic protection system of PWA Bangpakhong_ Repairing and Improvement cathodic protection system project of water pipeline at Wat Khao Sa-at Pump station. The pipe to soil potentials test is accordance with the N.A.C.E. SP-0169 standard. A negative (cathodic) potential of at least 850 millivolts with the cathodic protection applied. This potential is measured with respect to a saturated copper-copper sulfate reference electrode contacting the electrolyte. Voltage drops other than those across the structure-to-electrolyte boundary must be considered for valid interpretation of this voltage measurement, which the cathodic protection system can work for a lifetime of 40 years.