Fire-Rate Wiring

About

Overview

Codes worldwide require fire protection for emergency feeder circuits in high-rise buildings, places of public assembly and institutions such as health care centers. Historically, this was achieved by running conventional cables behind a heat barrier such as a gypsum board or hollow concrete block; or by embedding the conductors in concrete.

Today, while these ‘construction methods’ of fire protection are still common; there is a transition underway to use fire-rated cables that maintain circuit integrity in a fire. The test to qualify a cable as 2-hour fire-rated is the ANSI/UL 2196 (ULC S139 in Canada). This protocol utilizes the ASTM E-119 time-temperature curve, and requires that cables remain operational after exposure to temperatures up to 1850°F (1010°C) for two hours followed by the full force of a firefighter's hose stream.

Fire-Rated Specialty Wiring Systems

Pentair Thermal Management has the original and premier brand of fire-rated cable—Pyrotenax brand—that meets the most stringent fire test standard in the world. The primary applications are fire pump and emergency generator feeders, fire alarm system wiring, and other circuits requiring protection such as pressurization and extraction fans.

Pyrotenax Mineral Insulated cable is composed entirely of non-combustible and inert materials. In addition to inherent fire-resistance properties, MI finds application for space-saving compared to conduit and wire in confined spaces, as well as for prevention of migration of vapors or gases through traditional cables.

Benefits
Built-In Fire Resistance

Fire-rated cables have built-in fire resistance, as opposed to fire-rating of conventional cables that require heat barrier systems such as gyproc enclosures, or encasement in 2 inches of concrete.

The advantages of fire-rated cables become more apparent as the codes call for longer durations of fire resistance. A 1 hour fire resistance is relatively easily met with gyproc enclosures or concrete. Codes however increasingly call for 2 hour fire resistance, which means a more costly and more complex construction for adequate protection of conventional cables.

Pentair Thermal Management cables:
  • Are 2-hour fire-rated cables, which extends time for fire-fighting
  • Are listed for fire resistance of electrical circuits; whereas neither gyproc enclosures nor concrete are tested or listed for protection of electrical cables
  • Do not require a fire barrier
  • Save space and cost
  • Reduce site coordination issues
  • Have accessible fire rated splices
Technology
Mineral Insulated Technology

Mineral insulated cable a 2-hour fire-rated cable listed by Underwriters Laboratories (UL) and Underwriters Laboratories of Canada (ULC) since 1980. Mineral insulated cable is ideal for fire protection of critical circuits because it:

  • Is inherently fire-resistant due to its totally inorganic construction
  • Is fire-proof, non-ageing, mechanically strong, small diameter, and pliable to handle
  • Is manufactured from copper and magnesium oxide, and features zero smoke, zero flame spread and zero fuel contribution
  • Has tough construction, yet allows the cable to be bent and molded to fit into tight spaces
  • Can withstand mechanical abrasion without additional mechanical protection
  • Is an environmentally clean electrical cable that does not burn, produce smoke, or contribute fuel when exposed to fire conditions