Test results, the cathodic protection system of MWA Repairing the cathodic protection system (Impressed current) of water pipeline at Soi Suksawat 53. 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 20 years