To avoid chaos in junction boxes, I have designed a plate for myself that is suitable for a 4-channel relay module, a step-down converter and up to 14 luster terminals (Screw terminal block connector / Lüsterklemmen). The cables can be pulled through smaller channels or attached to various prefabricated points using cable ties.

The Adelid ABS junction box 150x150x80mm was used as the box, as it offers simple internal mounting via rails (see picture).

An external Arduinio / RaspberryPi is used as the microcontroller and connected to the 4-channel relay by cable. Wireless relais was not used as the irrigation control box is located in the cellar and the reception there is rather unreliable. The 4-channel relays control 4 solenoid valves for garden watering. The step down converter is necessary because some solenoid valves only support DC 12V instead of DC 24V.

As the box is located in a damp room, the print was printed with PETG.

Used screw sizes:

All used screws are self-tapping and from the 500 pieces stet (see used materials below).

• 4 Channel Relay
  4x M2.3 * 5 mm
• Step Down
  2x M3 * 5 mm
• Main plate (junction box insert)
  8x M3 * 6 mm

Used materials:

• Adelid ABS junction box 150x150x80
• 4 Kanal DC 5V Relaismodul
• LM2596 DC to DC Step Down Module
• 14x  1.5 – 2.5mm² Screw terminal block connector (Lüsterklemmen)
• Jumper cable
• Colored copper wire
• 500 pieces Black self-tapping screws set M2, M2.3, M2.6, M3
• Cable ties (optional)