The wet flashover voltage of an insulator depends partly on the angle at which the water-drops fall but mainly on the quantity of water striking the insulator. A visual estimate of the angle and a measurement of the vertical rate of fall does not give a satisfactory indication of the quantity striking the insulator if spiral nozzles are used. A suggestion is made to improve the consistency of wet-test results by using plain nozzles and by making two simple measurements of spray intensity.