Grasslin segmental timers are accurate to 15mins. These timers are most commonly used for controlling lighting and hydroponic feeding systems. Segmental timers from Grasslin are simple to use you just set the 15 minute segments around the dial as on or off and away you go.
contactor relay to protect the timer from the high inductive load of the light. If you don’t the segments on the timer will fuse shut meaning your lights will stay on when they should turn off.