Choosing a Control Box Location

The SPP enclosure is built to withstand years of outdoor use in any weather, but it's often more convenient to install it inside a scale house or maintenance building. Keep two things in mind when choosing a spot:

1. It needs to be near the incoming power for your fans, since you'll be wiring the contactor coil power into the relays on the unit.

2. It needs to acquire a cellular signal through the antenna on top of the unit.

Avoid installing the SPP:

• Inside a thickly sheeted metal building

• In an area with insufficient cell signal

• Inside a concrete structure

Use the ¼ in. mounting holes and appropriate bolts to mount the unit to your chosen surface.

Installing the Sensor

Mount the sensor outdoors, out of direct sunlight, where it can get a true ambient air reading. There's a screened/slitted opening on the bottom of the sensor that lets air pass over it — make sure this screen faces downward.

Use the 5mm (~3/16 in.) mounting holes on the sensor enclosure to secure it.

Step 1: Prepare the Unit for Wiring

Remove the faceplate via the six Phillips screws on the front.

Identify the circuit boards:

• Front board — 2400 Logic Board: holds the clock's coin cell battery, LCD screen, relays, and sensor cable terminal. The eight relays sit at the bottom-left; the sensor cable terminal is the light gray RJ45 connector below and to the right of the LCD.

• Back board — 1400 Power Board: holds the incoming power terminals (labeled L1 and L2), the earth ground terminal (E GND), and the circuit-protection fuses.

There are eight knock-out hole patterns on the bottom of the enclosure for wiring access. Use caution drilling these out so you don't damage the internal boards.

Step 2: Wire In the Fans

The eight relays are set up into two groups: Program A runs relays #1–#4, Program B (if applicable) runs relays #5–#8. (Custom PACs may have a different relay setup — check with your dealer.)

Phase converter (if required): the SPP closes relays in ascending order and opens them in descending order within each program — for example, Program A turns ON in the sequence #1 → #2 → #3 → #4, and OFF in the sequence #4 → #3 → #2 → #1. Wire the phase converter into relays #1 and #5 to keep this sequence correct.

Wiring the fans:

• Bring 120V power (line) to the COM (common) side of the relay

• Bring the load side from the fan's starter coil to the NO (normally open) side of the relay

Notes: you don't need to wire every relay for operation, the SPP doesn't supply power to the NO or COM side of the relay, and since solid wire can vibrate loose, it helps to hook the wire around the terminal screw.

Step 3: Connect the Sensor Cable

Remove the four screws securing the sensor box cover, then plug one end of the sensor cable into the RJ45 terminal on the sensor board and the other end into the RJ45 terminal on the 2400 Logic Board. Connect the sensor cable beforeapplying power to the PAC, to ensure the proper initialization sequence.

Step 4: Connect Incoming Power

The SPP needs its own dedicated 120VAC line from a 15–20 amp breaker, plus an isolated earth ground to prevent interference and phantom voltages.

• Connect line voltage to terminals L1 and L2

• Connect earth ground to terminal E GND

Step 5: Replace Covers and Test the Unit

Replace and secure the faceplate with its six Phillips screws (double-check the ribbon cable is reconnected first), then replace the sensor box cover with its four screws. From here, test the unit following the steps on the Operation page.