18/4 Alarm Wire Shielded Plenum Cable 100FT - Reliable Security Wiring

In this review of the 18/4 Alarm Wire Shielded Plenum Cable 100FT, the bottom line is simple: this cable is built for installers and DIYers who need a flexible, plenum-rated solution for security, access control and low-voltage audio or communication lines. The reviewer found the stranded pure copper conductors and aluminium foil shielding deliver reliable conductivity and predictable performance, while the CMP/CL3P/ FPLP plenum jacket adds a meaningful safety advantage for in-ceiling or plenum installs. For anyone wiring alarm panels, intercoms or PA systems where fire rating matters, this cable is worth considering.

Key Features

• 100 ft length: Provides a practical single-roll length for running multiple zones or a long run without splicing, reducing installation time.
• Stranded pure copper conductors: Offer lower resistance and better conductivity than CCA, which helps maintain signal integrity in alarm and access control circuits.
• Shielded with aluminium foil: Reduces electromagnetic interference for clearer audio and more reliable communication lines in noisy electrical environments.
• CMP/CL3P/FPLP plenum jacket: Flame-retardant jacket material gives added safety for plenum spaces and meets stricter building requirements.
• 300 V rating and temperature range: Rated to 300 V and usable from -10C to 90C, making it suitable for most indoor low-voltage installations.

Who It's For

This cable targets electricians, system integrators and building maintenance staff who install fire alarms, burglar alarms, access control, intercoms and public address systems and want a plenum-rated, shielded option. The stranded construction makes routing through conduit, cable tray and tight corners easier than solid conductors, which speeds installs and reduces breakage.

Less appropriate users include those who need outdoor direct-burial cable or heavy power wiring; the cable is intended for low-voltage indoor use and plenum spaces rather than exterior exposure or mains power runs.

Pros & Cons

Pros

• Stranded bare copper provides strong conductivity and flexibility for neat installs.
• Plenum-rated jacket (CMP/CL3P/FPLP) improves fire safety in ceiling and air-handling spaces.
• Aluminium foil shielding reduces interference for audio and communication lines.

Cons

• Not designed for outdoor or direct-burial applications, so additional protection is needed for exterior runs.

Specifications

Our Verdict

The 18/4 Alarm Wire Shielded Plenum Cable 100FT is a practical, cost-effective choice for indoor low-voltage installs where flexibility, shielding and plenum fire performance matter. Installers will appreciate the stranded copper for routing and the foil shield for cleaner signals, while the CMP-rated jacket provides added safety in ceiling and air-handling spaces, making it good value for professional alarm and access control work.

Frequently Asked Questions

Is this cable suitable for fire alarm systems?
Yes, it is designed for low-voltage fire alarm and security wiring and carries a 300 V CL3P rating with plenum flame-retardant jacket.

Can this cable be used outdoors?
No, the cable is intended for indoor use; outdoors or direct-burial runs require specialty outdoor-rated cable or additional weatherproofing.

Will the shielding help with audio and intercom lines?
Yes, the aluminium foil shield reduces electromagnetic interference, which improves signal clarity for audio, intercom and communication circuits.