[en] This paper describes a technique for obtaining voltage scaling parameters by measuring the plasma voltage on small-scale, static discharges. Validity of the static arc measurement is demonstrated by comparing the static arc voltage gradient for copper/G-10 with the muzzle voltages measured on various EML devices with bore diameters ranging from 1 to 10 cm. The experimental discharge chamber resembles a conventional, bolt-together railgun device with a length of 30 cm. The muzzle end is blocked and sealed to contain the plasma pressure. The discharge channel width is 6.35 mm and the discharge height is variable from 6.35 to 25.4 mm in increments of 6.35 mm. Rail width is varied with discharge height to maintain the plasma pressure constant at fixed current. The breech end is open to provide venting of arc ablation products. Both the rail and insulator surface are provided with thin replaceable liners to facilitate rapid clean-up after each test. Careful attention to tolerances combined with polyethylene gaskets and large bolting force are required to provide leak-tight operation. A series of tests has been performed using the most common railgun materials, copper electrodes and G-10 fiberglass insulation. The test current had a peak value of 145 kA (23 kA/mm) and a quarter cycle discharge time of 220 μs. The plasma voltage was measured at the muzzle end using a shunt resistance and a current transformer