Does anyone have a formula to figure short circuit AIC ratings using MI cable as a feeder? I typically use the formula shown in the Bussman catalog which is the same as Mike's. The manufacturer sent me the AC resistance of the cable but I don't have a formula to plug the information into. Thanks for any input
Marie Babbitt
Seems like some mixing of terms here, as to what data and for what purpose would be used. In short circuit calculations you're using the same formula, but an MI cable relevant data would be somewhat different from normally available cable's resistance/impedance data.
However, the impact of the cable type is normally very small and only would represent meaningful difference when used in mass-length, like same type cable for transmission, distribution and branch feeders at significant length combinations. Using non-metallic jacketed cable or 3-1/c in PVC conduit data would get you close. I somewhat doubt that the data would be available from the MI cable manufacturer, but who knows, but if it is then you can plug that data into your program or longhand
calcs.
