Can I hook the negative side of a circuit to a relay?

Probably a simple question, but I want to make sure I’m not missing something. I’m using several relays in my home for automations (trigger sirens, irrigation valves, etc). I usually hook the positive wire to the relay and hook the ground wire directly to the power supply. Can I reverse that and hook the ground to the relay and the positive directly from the power supply to the alarm/valve/etc? I assume it works the same, correct?

It depends what kind of power the device uses. If it’s AC power then it won’t matter. If it’s DC power then you need to make sure the polarity of the voltage to the device stays the same.

Other that that then it doesn’t usually matter if you switch the positive leg or negative leg.

But again if you are switching AC then it is convention to always switch the hot leg and never the neutral.

Thanks, I’m looking to do this with DC. I will make sure the polarity stays the same.