This instructable covers the integration of a Johnson Controls temperature control into an extension cord with switch and electrical outlet for controlling a freezer. For fermenting beer, a chest freezer is a fantastic platform but the factory controls are far too cold. This controller project effectively overrides those by cutting power to the freezer once it chills to the desired temperature. The controller in this project is further enhanced with a standard electrical outlet and light switch controller.
When the switch is on and the temperature is higher than the thermostat setting, the outlet is powerered. When the switch is turned off, or the temperature drops below the thermostat setting, the outlet is off.
1) Wire stripper
2) Phillips head screwdriver
3) Electric Drill with small drill bit may be required for attaching the controller to the metal electrical box.
The required parts for this project are:
1) Johnson Controls Thermostat control. This particular one is a model A19ABA. This was purchased from ebay for about $19.00.
2) Extension cord. Make sure this cord can carry the full amp load listed on the freezer or device you are attaching to it. Mine is a 12gauge "heavy duty" and can easily handle the current draw of this freezer.
3) A 2 gang metal electrical box. Available at a home center for about $2.00
4) Misc. electrical wiring. Everything in this project is 12-2 residential wiring or ROMEX. You will only need a few short or scrap pieces for this project. You can also clip down a 10" or so piece of the extension cord if you are frugal or don't have ROMEX scrap lying around. If you go that route, then use this piece whenever this instructable mentions your ROMEX wire.
5) 1 electrical outlet and 1 switch. These are available at a home center for $0.50-$1 a piece. You don't need anything fancy here.
6) Switchplate to cover the face. Optional, but better than getting shocked. Get the 2 gang where one side is switch plate and the other is for an outlet like in the picture.
Step 1: Prepare the Extension Cord
Clip off the female end of the extension cord. You may want to save this for another project. Then cut the insulation back a bit and strip the three component wires back about 1".
While you've got the wire strippers out, cut back some of the ROMEX electrical wire the same way.