Most laboratories do not test for Ethyl Glucuronide (EtG), a metabolite of ethanol. Rather, the majority are looking for Urine Alcohol Content (UAC).
EtG can be detected, on average for 60+ hours. Far longer than a measurable UAC. However there are wide inter-individual variations in EtG tests. The last study I reviewed, individual detection ranged from 30-110 hours, after consumption of an equal amount of alcohol.