If you want to stay safe and keep those new bare bone ballasts covered and protected. Then invest in the boxes!! Side vented slots both sides to help dissipate the heat. Handle and all hardware included. Makes for easy transport.
Every go to the Hardware store looking for specific items and had to answers uncomfortable questions. Then you have to go to another store and go through the whole process again. Still with no luck.
Standard industrial "old school" Double Pole Double Through Relay (DPDT). Essential if one wants to maintain more then one grow room. CSA approved. Remember these are Voltage specific !!!