It was brought to my attention by a reader of Hoptomology that it would be wise to add a relay to my temperature controller build. The reason being it will render the contacts on the controller safer and extend their life. They are only rated for 10 amps and a refrigerator or freezer may draw more than that for a split second when it kicks on. Up until this point I haven’t had any issues, but it never hurts to go the extra mile when it comes to wiring and electricity. Safety should always be your first priority!
Another thing that should always be observed when using electricity with liquids nearby, is plugging the unit into a GFCI (Ground Fault Circuit Interrupter) receptacle instead of a normal one. This way you have added protection for yourself should you accidentally come into contact with your beer or sanitizer etc. and then touch the controls. Any short circuit due to the moisture will trip the GFCI and save you from a nasty shock. I tried installing a GFCI in the actual controller box, but found that it tripped the circuit quite often when it turned on, leaving my precious beer and yeast to warm up until I was able to notice. Instead, just plug the unit into a wall outlet with a GFCI, and you’re set. (Thanks for your input Henry!)
I bought the relay (Part # PB321-ND) and relay socket (Part # PB642-ND) from DIGIKEY. It cost me about $31 shipped to my door. I’m sure you could find somewhere else cheaper, like a local electronics store, but I’m guessing the connections may vary slightly. I thought I’d stick with what I know and get the parts that were suggested by Henry.
Here is the updated wiring diagram with the relay added into the circuit.