LA303R 0-250 VAC 3-phase Lightning Arrestor Delta LA303-R For 250 VAC, Three Phase, 3 or 4 Wire Service Rated voltage 250 Volt, three or four wire service. Used when three hot wires of a three phase system are to be protected. Weather Proof N-4 Case Dimensions: 2 1/4" Diameter, 4 1/2" High.