It’s an old thread but still a lingering issue on how to best protect the controller. My setup and situation consists of ~30 valves for field (farm) irrigation using well water. There are some cases where I do run 4 valves at the same time. My nemeses are 1) the sun that prematurely compromises a solenoid and it fails with a short and 2) moles that chew the direct burial cable and cause a short. Admittedly I should be protecting against those 2 things as well (encase the solenoids/valves and run the cable thru conduit) and we do work on them as we come to the issue. But when we’ve had a short, the triacs or the 24VAC transformer tend to fail before the main fuse in the controller opens. And as mentioned by Ray, I can’t install a smaller fuse in the controller because it’ll “falsely trigger.” For now, I created an ESP-based current sensor on the transformer that will cut-off power to the controller if it senses >1A of current. But since this is software based, the reaction is slow and may not trigger a cut-off fast enough. So I’ll take some of the advice here and add 1A inline fuses to the common lines and monitor.