To connect all the hot wires together I used a terminal block which made it easy. int relay4 = 5; delay(timeC); allOff(); So you could get 4 of those and 8 shift registers, theres probably and easier way to do this but if your proficient in arduino … As a contractor I should tell you that the box should really be water tight and have more protection around the high volt side in case of loose wire spark. digitalWrite(relay6, LOW); digitalWrite(x, HIGH); allOff(); In this arduino relay control tutorial we will simply learn How to interface a Relay with Arduino. delay(timef); Add the following snippet to your HTML: