I am curious on what specifically causes a suction line to sweat (excess condensation dripping) and to what level is it acceptable. I was taught that if a suction line is sweating to call it out for further evaluation. Any input is greatly appreciated.
A sweating suction line is perfectly normal.
Excessive sweating might be caused by not insulated well enough or too cold due to poor air flow over the evaporator.
Some types of systems might sweat a lot because of being overcharged but in that case, usually the whole compressor will be sweating.
Mike Whom ever taught you that needs to go back to school. Sorry could not help myself. Have you ever taken a 42 degree beer out of the refrig and place it on the table where it is 73 degrees. It sweats does it not Same with a suction line . I worry when it is not sweating. The suction line is required to be insulated within or above any habitable living space.