18/6 100ft Thermostat Wire - Solid Copper, CL2 Low Voltage Cable

In this review of the 18/6 100ft thermostat wire from NATIONAL Wire&Cable the bottom line is simple: this is a dependable choice for homeowners, contractors, and technicians who need clear signal transmission between thermostats and HVAC equipment. The most compelling reason to buy is the use of 100% solid copper conductors and the CL2 ETL listing, which together deliver reliable conductivity and code-friendly installation for low voltage applications. The review covers real-world handling, compatibility with smart thermostats, and where the cable shines or shows limits.

Key Features

• Made in USA: Manufactured in New York since 1972, the cable offers traceable domestic production and consistent manufacturing quality.
• 100% Solid Copper Conductors: Premium solid copper provides excellent electrical conductivity for accurate thermostat signaling and reduced voltage drop over 100 ft runs.
• CL2 ETL Listed: Rated for in-wall low voltage use, the listing helps simplify meeting local code requirements for thermostat and doorbell wiring.
• Multi-conductor 18/6 Configuration: Six conductors allow connections for common, power, and multiple control signals which is useful for modern HVAC and smart thermostat installs.
• Durable Construction: The jacket and individual conductors are built to withstand typical installation stresses and maintain a stable connection once terminated.
• Lifetime Warranty: Backed by a lifetime satisfaction warranty, giving extra confidence for professional and DIY installations.

Who It's For

This cable is aimed at residential and light commercial HVAC contractors, electricians, and savvy DIYers who need a reliable low voltage run for thermostats, doorbells, or control circuits. It is particularly suitable when installers prefer solid copper conductors for long-term conductivity and when an ETL CL2 rating is required for in-wall routing.

Those who should look elsewhere include projects that require stranded wire for frequent flexing or portable use, and very long commercial runs where different gauge sizes or shielding might be specified. If extreme mechanical abuse or constant movement is expected, choose a cable designed for flexible or armored use instead.

Pros & Cons

Pros

• High conductivity from pure solid copper conductors ensures stable thermostat communication.
• Made in USA manufacturing provides consistency and traceability for professional use.
• CL2 ETL listing supports safe in-wall installation for low voltage wiring in homes and businesses.
• Lifetime warranty offers added peace of mind for installers and homeowners.

Cons

• Some customers report the cable can feel fragile during rough handling, so care is needed on-site.
• Not suitable where a stranded, highly flexible conductor is required for movable equipment.

Specifications

Conductor	100% solid copper
Gauge	18 AWG
Configuration	18/6 (six conductors)
Length	100 ft
Listing	CL2 ETL Listed
Applications	Thermostat, doorbell, HVAC low voltage control
Origin	Made in USA (New York)

Our Verdict

The 18/6 100ft thermostat cable is a solid, sensible purchase for most residential and light commercial HVAC wiring needs; its solid copper conductors and CL2 ETL listing make it a reliable, code-conscious choice. Installers who handle the cable carefully will find it good value because of consistent conductivity, domestic manufacturing, and a lifetime warranty that reduces long-term concerns.

Frequently Asked Questions

Is this wire suitable for in-wall thermostat runs?
Yes. The CL2 ETL listing indicates it is rated for in-wall low voltage installations common to thermostat and doorbell wiring.

Will it work with smart thermostats?
Yes. Customers report successful use with modern smart thermostats thanks to the consistent signal transmission provided by solid copper conductors.

Is this cable flexible for repeated movement?
No. The 100% solid copper construction is not intended for frequent flexing; choose stranded wire if the run will experience regular motion.