I am having an issue with voltage, The problem is i have taken over where I am and have (1) 370 P 250 A-E and (1)370 SS 250 A-E hot water heaters from PVI. The elemants keep blowing out after a week or so. Also the fuses keep blowing. 480 3 phase. This is happening on both units. I contacted PVI and they said to check the ground, I put my amp meter on the ground at the ground and am getting 0.28 amps this is even with the main breaker shut down at the main panel. What else can I look for? I have verified all the correct wiring and all correct fuse sizes.