Thermostat Copper Wire 18-8 Brown 100ft - Durable Thermostat Cable

In this review of the Thermostat Copper Wire (18-8 Brown, 100ft) the bottom line is simple: this is a dependable, code-compliant thermostat cable for HVAC, alarm and low-voltage control work. The reviewer found it best for installers and DIYers who need a full 100 ft spool of color-coded cable with a robust PVC jacket and clear temperature and voltage ratings. The cable's UL listed Type CL2 and ETL compliance, along with a -20C to 60C temperature range and 150 V rating, make it a practical choice for indoor thermostat and signal wiring where durability and safety approvals matter.

Key Features

• UL Listed Type CL2: Provides confidence the cable meets common building and low-voltage installation standards for in-wall use.
• Temperature Range: Rated from -20C to +60C so the cable is suitable for most indoor HVAC and control environments.
• 150 V Rating: Supports typical thermostat and signal voltages without overrating or unnecessary bulk.
• PVC Outer Jacket: A heat, moisture and sunlight resistant PVC jacket adds durability for runs through basements, attics and service spaces.
• Insulation Options: PVC or polypropylene insulation with color-coded conductors simplifies identification during installation and termination.
• 100 ft Length: A full spool covers standard installs without needing to splice, saving time and preserving signal integrity.

Who It's For

This cable is aimed at homeowners doing thermostat upgrades, HVAC technicians wiring controls, and low-voltage installers working on intercoms, doorbells, or annunciator systems. It is especially useful when a long, continuous run is required and compliance with UL and NEC Article 725 is desirable.

It is less appropriate for high-voltage mains wiring, outdoor direct burial runs, or situations that require specialized shielded cable for audio or sensitive signal isolation; in those cases a purpose-designed shielded or outdoor-rated product should be chosen.

Pros & Cons

Pros

• Well-made conductors and proper gauge make stripping and crimping straightforward for clean terminations.
• UL 13, CL2 and ETL compliance mean the cable meets recognized safety and installation standards.
• Durable brown PVC jacket resists heat, moisture and sunlight for added longevity in common service locations.
• 100 ft length and color-coded insulation offer good value and ease of identification during hookup.

Cons

• Not intended for direct burial or outdoor-only installations without additional protection, limiting some exterior uses.
• Brown jacket is practical but may be harder to hide in light-colored finishes compared with white alternatives.

Specifications

Type	Thermostat Cable, UL Listed Type CL2
Gauge/Configuration	18-8 copper conductors
Length	100 ft
Temperature Rating	-20C to +60C
Voltage Rating	150 V
Insulation	PVC or polypropylene, color-coded
Jacket	Brown PVC, heat/moisture/sunlight resistant

Our Verdict

The Thermostat Copper Wire 18-8 Brown 100ft is a practical, code-aware choice for thermostat control, HVAC and low-voltage signal wiring. Its combination of UL listing, ETL compliance, durable PVC jacket and full spool length makes it good value for installers and homeowners who need a reliable, easy-to-install cable for indoor runs.

Frequently Asked Questions

Is this cable rated for in-wall installation?
Yes, it is UL Listed Type CL2 and meets NEC Article 725 requirements for many in-wall low-voltage installations.

Can this be used outdoors?
The PVC jacket resists moisture and sunlight, but the cable is not specified for direct burial or permanent outdoor exposure without additional conduit or protection.

Will this work with smart thermostats?
Yes, the 18-8 conductors and 150 V rating are suitable for typical smart thermostat wiring and HVAC control systems.