Applying heat trace cables to branch sprinkler lines on fire suppression piping can be risky business. Protect yourself with the correct information because, fire suppression branch line heat tracing may not be approved by the fire inspector. 

One fire inspector we consulted said, "unless it's been tested to all of the NFPA 13 guidelines and specifications, forget it."

What is NFPA 13 and what does it states?
NFPA 13 is the standard for the installation of Sprinkler Systems. It is not a testing standard as some fire inspectors may believe. 

NFPA 13 (4-3.1.8.2) states that you cannot use heat tape instead of a heated valve room to freeze protect preaction valves, deluge valves, and supply pipe. 

NFPA 13 (5-14.3.1.2) states that pipes leading up to this point can be freeze protected by a reliable means, which includes electric heat tracing. 

NFPA 13 chapters 4 & 5 stat that branch line must be preaction, dry type, or antifreeze systems.

Additionally, I.E.E.E. recommends that the fire alarm panel should have an alarm input from the heat tracing control device that monitors pip temperature, voltage, and electrical current of the heat tracing cable. 

Is there a UL listing for branch circuit lines?
To our knowledge, there is no listing to meet. Read the fine print in the products UL listing for heat tracing of fire suppression pipes, and you'll see it excludes branch sprinkler lines.

Delta-Therm's Ed Witte states, "using heat trace cable for piping other than the branch lines can be acceptable by building personnel if the installation is in compliance with NFPA 13, but the system must be approved by the authority having jurisdiction prior to the project start to avoid any possible issues."

When you have an application for fire suppression or sprinkler pipe heat tracing, remind the contractor to get approval for the fire inspector in writing.