What the OP did was build a simple irrigation controller for an existing irrigation system. Most irrigation systems use electronic solenoid valves that open wh

What the OP did was build a simple irrigation controller for an existing irrigation system. Most irrigation systems use electronic solenoid valves that open when very low current 24 VAC power is applied to the two terminals. Take a look at the Spec for a valve from Rainbird: https://www.rainbird.com/sites/default/files/media/documents/2021-06/d37554-0719_gsv-techspec_fin_web.pdf https://www.rainbird.com/sites/default/files/media/documents... Electrical Specifications: • Power: 24 VAC 50/60 Hz (cycles/second) GBS25 Solenoid • Inrush Current: 0.41 A (9.84 VA) • Holding Current: 0.20 A (4.80 VA) at 60 Hz, 0.23 A (5.40 VA) at 50 Hz If you have a sprinkler system, you can replace the on/off valve with a solenoid valve and then you're able to control the system electronically using a 24 VAC power supply and a switch. The OP replaced the switch with a relay, which is a switch that can be actuated by the lower voltage from something like a microcontroller.