Monoprice

Monoprice 113729 Nimbus 18AWG CMP-Rated Plenum Speaker Wire

4.3 (118 reviews)

Plenum-rated 18AWG pure copper speaker wire with flexible CMP jacket for safe in-wall and commercial installations.

$40.99*
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*Price sourced from Amazon.com. Last updated:Jun 27, 2026.Price and availability are subject to change.

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Overview

The Monoprice Nimbus Series 113729 is an 18AWG, 2-conductor speaker wire carrying a CMP plenum rating, which certifies it for installation in the air-handling spaces found above drop ceilings and below raised floors in commercial and residential buildings. This rating is not optional in many jurisdictions — building codes and insurance requirements often mandate plenum-rated cabling in these spaces due to the reduced smoke and toxicity characteristics of the jacket material in the event of a fire. Monoprice addresses a common complaint about plenum cables by using a jacket material that is noticeably softer and more flexible than the stiff PVC typically found on plenum-rated wire, making it easier to pull through conduit and route around corners.

The conductors themselves are made from high-purity oxygen-free bare copper, which provides consistent electrical conductivity and minimizes signal degradation over the length of the run. The red and black color coding on each conductor simplifies installation by making polarity identification immediate and unmistakable. At 50 feet, this roll is sized for individual speaker runs in typical room layouts — enough to reach from an amplifier or receiver to a ceiling-mounted or wall-mounted speaker in most configurations. The cable is backed by Monoprice's lifetime warranty, covering manufacturing defects for as long as you own it.

Key Features

Lifetime Warranty on ALL Cables: With Monoprice's Lifetime Warranty you can rest assured we stand behind our products and our customers.

The Plenum (CMP) rating indicates that the cable complies with fire safety and insurance requirements, making it safe for use inside the walls of residential and enterprise class buildings.

This speaker Wire | features conductors made of high purity oxygen-free bare copper.

Monoprice Plenum Speaker Wire | uses a high quality material that is soft -er and more flexible than on traditional plenum rated jackets.

Easily identifiable Red and Black conductors.

Specifications

Brand
Monoprice
Series
Nimbus
Model
113729
Gauge
18 AWG
Conductors
2
Rating
CMP (Plenum)
Conductor Material
100% Pure Bare Copper
Length
50 feet
Safety
UL Plenum Rated
Identification
Red and Black Color-Coded Conductors
Warranty
Lifetime

Pros & Cons

👍 Pros

  • CMP plenum rating meets fire safety codes for installation in air-handling spaces and inside walls
  • Pure bare copper conductors deliver reliable signal transmission with low resistance
  • Flexible jacket material is softer than traditional plenum-rated cables, making it easier to route through tight spaces
  • Lifetime warranty from Monoprice provides long-term assurance on the cable

👎 Cons

  • 50-foot length may not be sufficient for larger commercial installations, requiring multiple rolls or splices
  • 18AWG gauge is not ideal for long runs exceeding 50 feet or high-power amplifier setups
  • Two-conductor design limits use to single-speaker runs and does not support bi-wiring
  • No markings or footage indicators printed on the jacket to help measure lengths during installation

Frequently Asked Questions

The CMP (Communications Multipurpose Plenum) rating means this wire meets fire safety standards for installation in plenum spaces — the areas above drop ceilings and below raised floors used for air circulation in buildings. Plenum-rated cables produce less smoke and toxic fumes if exposed to fire.
This wire uses 100% pure bare copper conductors, which provide better conductivity and signal quality compared to copper-clad aluminum alternatives.
The two conductors are color-coded red and black for easy identification during installation, so you can maintain consistent polarity across all your speaker connections.
18AWG is suitable for shorter to moderate speaker runs, typically up to about 50 feet for most home and commercial audio applications. For very long runs or high-power setups, a thicker gauge such as 16AWG or 14AWG would be more appropriate.