there are five categories,1,2..5 I gess that system of categorie 1 is less critical than sytem categori 2 or 3,4, and 5 etc...and each categorie refers to service conditions which are different from service condition of sytem cat 2 ,3,4 or 5
What i'm looking for is how to define tese categories.
Level A, B, C loading specifications are some things else