Hi guys and gals. I have a constant current welder. 150 Amps DC/ 230 Amps AC output. There is no provision for measuring output current when the machine is welding. I'm thinking of adding a shunt to either the work lead or the return lead. I don't know what size and rating I need. The input voltage is 220-250 volt. I'm often hooked up to a 230 volt 60 HZ source. I'm often welding DC work negative. Would there be any difference in measuring the AC and DC? Are they different shunts???? Thanks a ton.