18/3 500ft Thermostat Wire Solid Copper 18 Gauge - 500ft Reel

In this review the 18/3 500ft thermostat wire is examined for homeowners, HVAC professionals and installers who need a long run of low-voltage cable. The bottom line: this solid copper, ETL CL2 rated cable is a practical choice when durability and compliance matter, offering a 500ft reel that covers multiple thermostat, alarm or control runs without splices. The focus here is on real-world use, ease of handling and how the cable stands up to indoor or covered outdoor installations where a 150V power limited rating and temperature range matter.

Key Features

• Solid copper conductors: Provides reliable conductivity and consistent signal for thermostats and low-voltage controls over long runs.
• ETL CL2 rating: Meets power-limited circuit safety standards for indoor installations and many building code requirements.
• Heat, moisture and sunlight resistant jacket: PVC outer jacket increases durability for protected outdoor routing and utility spaces.
• Strip-friendly insulation: Insulation strips easier and resists tearing, saving time when terminating multiple connections.
• Wide temperature range: Rated from -20C to +60C so it handles typical basement, attic and covered exterior conditions.
• 500ft length: A single reel reduces the need for joins on multi-zone HVAC systems or several alarm and intercom runs.

Who It's For

The cable is best suited for HVAC technicians, electricians doing low-voltage work and DIY homeowners who want a long single-reel feed for thermostats, doorbells, intercoms and alarm systems. Its ETL CL2 listing and 18 gauge solid copper conductors make it appropriate for control wiring and signal systems where a tidy, dependable connection is required.

It is not intended for high-voltage mains wiring or exposed direct burial without additional protection; anyone needing stranded wire for flexible runs or specialized outdoor burial cable should look elsewhere.

Pros & Cons

Pros

• Solid bare copper offers stable conductivity and simple terminations for thermostat and control circuits.
• ETL CL2 and temperature rating support common building and HVAC installations.
• Durable PVC jacket resists heat, moisture and sunlight for protected outdoor routing.
• 500ft spool reduces waste and the need for mid-run splices on multi-zone jobs.

Cons

• Some customers report mixed impressions of jacket toughness, so it may feel less rugged than heavier duty cables in rough handling situations.

Specifications

Conductor	18 gauge solid copper
Conductors	18/3 (three conductors)
Length	500ft
Rating	ETL CL2, 150V power limited
Temperature	-20C to +60C
Jacket	PVC, heat/moisture/sunlight resistant
Applications	Thermostat control, alarms, intercoms, door bells, signal systems

Our Verdict

The 18/3 500ft solid copper thermostat wire is a sensible buy for installers and homeowners who need a long, compliant reel for low-voltage control and signal work. It combines ETL CL2 safety, a durable PVC jacket and strip-friendly insulation for faster terminations, making it good value for multi-run HVAC, alarm and intercom projects.

Frequently Asked Questions

Can this cable be used outdoors?
Yes for protected outdoor runs and covered spaces; the PVC jacket resists sunlight and moisture but direct burial is not recommended without conduit or additional protection.

Is the conductor solid or stranded?
This product uses solid bare copper conductors, which are common for thermostat and fixed control wiring.

What voltage and temperature does it support?
The cable is rated 150V power limited (ETL CL2) and for -20C to +60C operating temperatures.