Temperature Control - Thermostat Cables

Summary: Temperature Control - Thermostat Cables

Temperature Control — Thermostat Cables

Windy City Wire manufactures SmartWire® low-voltage thermostat cable designed for dependable temperature control, building automation, and HVAC installations. This temperature control wire and cable category features plenum-rated, non-shielded constructions that support common thermostat (tstat/t-stat) connections, zone control, and relay interfaces in residential, commercial, and institutional environments. All options are UL Listed C(UL)US CMP/CL3P for use in air-handling spaces and power-limited control circuits.

Every SmartWire® thermostat cable is made in the United States and built for consistent performance with bare copper conductors, easy-to-identify color coding, and a durable plenum jacket. SmartWire Glide Technology® lubrication is applied to the cable jacket during manufacturing and reduces friction during pulls by up to 70%, helping installers move faster with fewer snags and less rework.

Why choose SmartWire thermostat cable

• UL Listed C(UL)US CMP/CL3P for plenum spaces and power-limited control circuits.
• Bare copper conductors support stable control signaling and reliable power to low-voltage devices.
• Non-shielded plenum constructions simplify stripping, terminations, and service work.
• Consistent jacket and roundness for smooth pulls and manageable routing in tight spaces.
• SmartWire Glide Technology® lubrication reduces pull resistance by up to 70%.
• Color-coded conductors help standardize connections and speed troubleshooting.
• RoHS compliant materials.

Common applications

• Thermostats (tstat/t-stat) and room sensors
• Furnaces, air handlers, rooftop units, and heat pumps
• Zone valves, dampers, and zoning panels
• Boiler and chiller controls
• Relays and control modules for HVAC automation

About 18 gauge thermostat wire

These thermostat cable options utilize 18 AWG conductors, the most widely used size for control circuits in HVAC systems. Installers can choose the conductor count needed for single-stage, multi-stage, or accessory control requirements without oversizing the cable or sacrificing flexibility.

Available constructions

• 18 AWG 4 Conductor Bare Copper Plenum CMP/CL3P: A dependable choice for standard heat/cool thermostat runs and basic control loops. Color code: Black/White/Red/Green for straightforward terminations.
• 18 AWG 5 Conductor Bare Copper Plenum CMP/CL3P: Adds a spare/common conductor for modern thermostats and connected HVAC devices. Ideal when a “C” wire is required for power-hungry displays or Wi‑Fi units.
• 18 AWG 6 Conductor Bare Copper Plenum CMP/CL3P: Supports accessory controls, sensors, or additional stages without running extra cable later. Useful for light commercial systems and expanded residential controls.
• 18 AWG 8 Conductor Bare Copper Plenum CMP/CL3P: Versatile 18 8 thermostat wire for multi-stage systems, zoning panels, and mixed control/sensor terminations in one pull. Helps future‑proof complex installations and renovations.

Conductor color codes

• 4 conductor: Black/White/Red/Green
• 5 conductor: Black/White/Red/Green/Brown
• 6 conductor: Black/White/Red/Green/Brown/Blue
• 8 conductor: Black/White/Red/Green/Brown/Blue/Orange/Yellow

Customization options

SmartWire® offers a wide selection of jacket and stripe colors to help standardize installations and make your work identifiable at a glance. Contact our team to discuss custom jacket and stripe combinations for your project or organization.

How Windy City Wire adds value

When you choose SmartWire thermostat cable from Windy City Wire, you get a US‑manufactured product designed for the realities of HVAC and building automation work. Our low-voltage products and solutions focus on safer plenum performance, consistent pulling and termination, clear identification, and dependable conductivity—so crews can complete installs efficiently and service them with confidence for years to come.

Looking for temperature control wire and cable for your next project?
From core thermostat cable to the conductor counts needed for advanced controls, Windy City Wire is ready to supply the 18 gauge thermostat wire you rely on. Talk with our team to select the right SmartWire® construction or explore custom color options for your standard builds.

Solutions: Temperature Control - Thermostat Cables

Temperature Control – Thermostat Cables built for today’s BAS and HVAC controls

Windy City Wire supplies temperature control wire and cable designed for reliable, low-voltage control of modern building automation and HVAC equipment. Our 18 gauge thermostat wire in multiple conductor counts supports common thermostat, zone control, and sensor applications across new construction and retrofit projects. With plenum-rated, UL Listed CMP/CL3P designs and RoHS compliance, these cables are suitable for use in return-air spaces and other areas where code requires a plenum rating.

Engineered for broad system compatibility

Our thermostat cable works seamlessly with leading temperature control systems and building automation platforms, including:

• Trane (e.g., Tracer), Honeywell, Alerton
• Johnson Controls, Siemens, Schneider Electric, Carrier
• Automated Logic, Delta Controls, Distech, and other BAS/BMS ecosystems

These systems commonly use 24V control and low-voltage signaling for thermostats (tstat/t-stat), zone controllers, VAV boxes, unit heaters, RTUs, heat pumps, boilers, chillers, fan coils, ERVs/HRVs, humidifiers/dehumidifiers, economizers, and field sensors (temperature, humidity, CO2/IAQ, pressure). Our non-shielded plenum thermostat cable provides the reliability and flexibility required for these circuits in most commercial environments.

Applications across industries and facilities

• Commercial office, multi-tenant, and mixed-use buildings
• Healthcare and life sciences (hospitals, clinics, labs)
• K–12 schools, higher education, and campuses
• Hospitality and entertainment (hotels, venues, arenas)
• Retail, grocery, and restaurants
• Industrial, manufacturing, and warehouses
• Data centers and mission-critical facilities
• Government, municipal, airports, and transportation hubs
• Multifamily and senior living

From centralized BMS integrations (BACnet, Modbus, and other typical BAS protocols) to conventional 1–2 stage heating/cooling, heat pump change-over, fan control, sensors, and auxiliary devices, our thermostat cable supports contractors and controls technicians in a wide range of use cases.

Why contractors choose our thermostat cable

• Correct gauge for HVAC controls: 18 AWG bare copper conductors provide a dependable balance of current-carrying capacity and manageable runs for most 24V control circuits used by thermostats and zone devices.
• Conductor counts that fit the job: Available in 4, 5, 6, and 8 conductors to match common wiring schemes—from basic furnace/AC stats to multi-stage heat pumps and advanced BAS terminals. For example, 4-conductor is frequently used for conventional heat/cool, 5-conductor often adds common, while 6 and 8 conductors support features such as heat pump reversing valves, auxiliary heat, economizer, or sensor leads. When additional points are required, many technicians choose 18 8 thermostat wire to minimize future repulls.
• Plenum-rated safety: UL Listed C(UL)US CMP/CL3P construction meets plenum requirements, making it suitable for return-air spaces and allowing a single cable family to cover many installation environments.
• Non-shielded design for typical t-stat runs: Most thermostat cable applications do not require shielding, keeping pulls straightforward while maintaining dependable signal performance for conventional analog and dry-contact circuits.
• Color-coded conductors: Standardized color sets simplify identification and terminations at the stat, air handler, VAV controller, or equipment. Typical sets include Black/White/Red/Green for 4-conductor and add Brown, Blue, Orange, and Yellow as conductor counts increase.
• Compliance standards: UL Listed, RoHS compliant materials support safety and specification requirements on commercial projects.

Common thermostat cable selections by application

• 4-conductor (18 AWG): Conventional single-stage heat/cool, fan, and 24V power where a common is not required, or for simple control circuits to unit heaters and basic RTUs.
• 5-conductor (18 AWG): Adds a common wire for many modern digital thermostats, improving power reliability for displays and Wi-Fi stats.
• 6-conductor (18 AWG): Useful for 2-stage systems, fan control, and an auxiliary or sensor lead; often selected when adding economizer or dehumidification control.
• 8-conductor (18 AWG): Preferred for heat pumps with reversing valve and auxiliary/emergency heat, advanced zone controllers, economizers, or extra sensor points—an ideal choice when future-proofing is a priority.

Where thermostat cable fits in BAS and HVAC control

• Thermostats and room controllers: tstat/t-stat connections for power, heat/cool stages, fan speeds, reversing valve, and auxiliary outputs.
• Terminal units and air handlers: VAV, FPB, fan coil, and AHU control wiring to actuators, relays, and safeties.
• Equipment interconnects: Rooftop units, split systems, boilers, chillers, and ERVs for low-voltage enable, mode, and status points.
• Sensors and inputs: Temperature, humidity, and IAQ sensors routed back to controllers in plenum spaces.

Installation notes for best results

• Route low-voltage control cabling separately from high-voltage power to reduce interference and ease serviceability.
• Use plenum-rated cable in return-air spaces as required by code; our CMP/CL3P rating supports these environments.
• Choose the conductor count that meets current requirements and allows for potential expansion to avoid repulls later.
• Follow equipment and controls manufacturer wiring diagrams for Trane, Honeywell, Alerton, and other systems to ensure proper terminal mapping.
• Verify continuity and device operation at startup to confirm correct stage, fan, and sensor performance.

Choosing the right cable for your next project

Whether you are wiring a single thermostat cable drop in a retail space or coordinating hundreds of control points in a campus-wide BAS, our temperature control wire and cable delivers consistent performance with the conductor counts professionals rely on. For many installations, 18 gauge thermostat wire balances voltage drop and flexibility, while an 8-conductor option provides room for additional stages, sensors, or future integrations.

Talk with our team about your specific system and site conditions—we can help match the correct thermostat cable to your Trane, Honeywell, Alerton, or other BAS/HVAC controls so your project installs cleanly and performs as expected.

Frequently Asked Questions: Temperature Control - Thermostat Cables

• What AWG conductors are available with these SmartWire Temperature Control Thermostat cables?

  18 AWG.

• What other colors are these SmartWire Temperature Control Thermostat cables available in?

  The standard outer jacket is white. Available conductor color code sets include:
  Black/White/Red/Green
  Black/White/Red/Green/Brown
  Black/White/Red/Green/Brown/Blue
  Black/White/Red/Green/Brown/Blue/Orange/Yellow

• Are these SmartWire Temperature Control Thermostat cables made with solid or stranded copper conductors?

  Solid bare copper conductors.

• What lengths are these SmartWire Temperature Control Thermostat cables sold in?

  1,000 ft. At Windy City Wire we manufacture and stock SmartWire Temperature Control wire in 1,000 ft length as our standard length.

• How is your SmartWire low-voltage Temperature Control cables sold on spools or in boxes?

  Our SmartWire Temperature Control wire is packaged in our patented RackPack carton. Learn more about our RackPack: https://windycitywire.com/solutions/rackpack-overview

Additional Links:

• Learn more about our SmartWire Cable
• The RackPack - Our patented cable delivery solution
• Our Transporters - RackPack Transportation Devices
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