not normal

[LJ in TX]

most likely defective installation how long have they been installed …and has this been happening since installation? most likely the base of the turbine as it is tucked under the roofing shingles is not well done nor well sealed. post back with more info. If these are very old turbines then its possible they are bad and need replacing but generally these leaks are caused by poor installation and sometimes just taking some roofing cement in a caulk tube and sealing all around the flahsing base of the turbine could solve the problem. if your roof is too high or has too high a pitch to where it is very slippery…then hire this out to a good roofing contractor…LJ