Would it be considerd against ethics to use city owned equipment for the athletic club dept, which is a county owned school? This equipment is being used after hours and weekends too for athletic club use.
If the city allowed the use, there is no ethical issue.
If you don't have permission it could be considered theft of city equipment and services. Especialy when something breaks. Even though it isn't your fault. Ask your supervisor about it. Being a nice guy can get you in serious trouble sometimes.
