Rather than post a detailed breakdown of my own panel, I decided to put together a build of a slightly leaner and cheaper panel. This one will cost $200-300 depending on your residency. Please read my other post about electrical safety before considering a build of this sort.
This panel is designed to be powered by 120/240 volts at 40amps and to control two elements (one at a time), and up to four other brewery-related circuits (pumps, fermentation chamber, etc.)
Power is delivered to the panel with a range cord (40a). Master power is controlled through a DPDT relay (40a, 120VAC coil), which is in turn controlled by a two-way toggle switch.
A 240 volt circuit is connected from the master power relay to both solid state relays (30a or 40a), which is then connected to NEMA L6-30 receptacles.
A 120 volt circuit is connected to the interior receptacle (which will power the raspberry pi or beaglebone black). GPIOs from this device connect to the solid state relays, a four channel relay module, and a patch panel for temperature probes. On the returning side of control circuit for the solid state relays, a three-way toggle switch will be utilized to ensure that only a single solid state relay is active at a time (auto-element 1, off, auto-element 2). Two three-way toggle switches will provide a manual override (manual-on, off, auto-on) for two of the four relays (most likely utilized for pumps), the other two will be controlled only through StrangeBrew Elsinore. All four relays will be connected to independent receptacles. Alternatively, an eight channel relay module could be used here at a similar cost, and more toggles could be added to allow for manual override.
Temperature probes are interfaced through an 8 port network patch panel, which is also used to network the Beaglebone Black or Raspberry Pi. Up to 7 DS18B20 temperature probes are utilized (a patch panel with >8 ports could be selected to allow for more, but I think this is beyond most needs).
The minimum size for the described control panel is approximately 12″x12″x5″.
Here’s a parts list (when possible, amazon product links provided)
1 x DPDT relay (40a, 120VAC coil), ~$30 (US)
2 x L6-30 receptacles, ~$ 10 (US)
1 x Project box or NEMA box