I will take a stab at this. Not sure what your buddy is trying to get at but if you measure 150amps per leg on a 200amp panel then you are drawing 150amps on that 200amp service. The amp meter should not indicate more than 200 amps and a fuse not blow or the fuses are rated to high over the allowable. Unless your buddy is mistaken like some people get and they add the 150amps times 3 legs = 450amps. But thats not how it works if you have 150 on each leg that is your total more or less. just my 2 cents ..
