Document Edition 2.4
Wiring General
All wiring must conform to NEC and local codes and regulations. Use earth ground isolating step-down Class 2
transformers. Do not use autotransformers. Determine supply transformer rating by summing total VA of product
and output loads.
Risk of Electric Shock or Fire
More than one disconnect switch may be required to de-energize the
equipment before servicing.
Input Class 2 Power Supplies are interconnected. Use only Class 2
sources suitable for interconnections.
All terminals are acceptable for Class 2 Circuit connections only
Use copper conductors only
Apply minimum 6.0 lb-in torque for tightening field wires into the terminal
blocks
Power
This product is designed to use a 24VAC Class 2 power supply. A single transformer may be used to power
multiple controllers and/or auxiliary field devices (actuators, etc.) provided the following conditions are met:
All devices MUST be ½ wave rectified. Mixing power between ½ wave and full wave rectified devices
will damage both the transformer and connected equipment.
The transformer is properly sized, including line losses for the total VA requirements.
Polarity is observed between controllers (with respect to 24~ and Gnd).
Each controller is grounded as shown in the diagram below. This is important to protect equipment and
ensure a common ground reference for RS-485 communications.
The transformer secondary is fused for its maximum rated load (4A max for Class 2 circuits).
Make sure to ground the controller using the ground lug that is available on the
controller. The controller uses the ground lug to establish a common reference for
communications. If the controller is not grounded then communication problems
may occur.
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