Programming Guide

VAV-SVP01A-EN 19
VAV Start Up/Check Out Procedure
Communication Wiring
WARNING
Hazardous Voltage!
Disconnect all electric power, including remote disconnects before servicing. Follow proper
lockout/tagout procedures to ensure the power can not be inadvertently energized. Failure to
disconnect power before servicing could result in death or serious injury.
WARNING
Electrocution and Fire Hazards with Improperly Installed and Grounded
Field Wiring!
Improperly installed and grounded field wiring poses FIRE & ELECTROCUTION hazards. To avoid
these hazards, you MUST follow requirements for field wiring installation and grounding as
described in the National Electrical Codes (NEC) and your local/state electrical codes. All field
wiring MUST be performed by qualified personnel.
Failure to follow these requirements could result in death or serious injury.
Communication Link Wiring
• Use 22 AWG Level 4 unshielded communication wire for most Comm5 installations.
• Limit Comm5 links to 4,500 ft and 60 devices maximum (without a repeater).
• Use the following termination resistors on all links:
•105
Ω at each end for Level 4 wire
• Use daisy chain topology.
• Limit zone sensor communication stubs to 8 per link, 50 ft each maximum.
• Use one repeater for an additional 4,500 ft, 60 devices, and 8 communication stubs.
Recommended Wiring Practices
To ensure proper network communication, follow these recommended wiring and planning
guidelines when installing communication wire:
• All wiring must comply with the National Electrical Code (NEC) and local codes.
• Although Comm5 does not require polarity sensitivity, Trane recommends keeping polarity
consistent throughout the site.
• Make sure that 24VAC power supplies are consistent in how they are grounded. Avoid sharing
24VAC between Comm5 controllers.
• Avoid over tightening cable ties and other forms of cable wraps. This can damage the wires
inside the cable.
• Do not run Comm5 cable alongside or in the same conduit as 24VAC power. This includes the
conductors running from triac-type inputs.
• In open plenums, avoid running wire near lighting ballasts, especially those using 277 Vac.
• Use a daisy chain configuration.
• Use termination resistors as described in "Termination resistance placement for Comm5 links"
• Insulate termination-resistor leads.
• Use only one type of communication wire; do not mix different types