Okay, let's break down the code requirements for fire-rated cable for Automatic Transfer Switch (ATS) control wiring.

Generally, No, There Isn't a Universal Code Requirement for 2-Hour Fire-Rated Cable for ATS Control Wiring, but...

There isn't a blanket NEC (National Electrical Code) requirement that mandates 2-hour fire-rated cable for all ATS control wiring. The need for fire-rated cable is driven by specific applications, building codes, and occupancy classifications.

Where Fire-Rated Cable Is Required for ATS Wiring


Emergency Systems and Legally Required Standby Systems

This is the most common scenario. NEC Article 700 (Emergency Systems) and Article 701 (Legally Required Standby Systems) are key.

NEC 700.9(D) and 701.11(B)

These sections state that wiring for emergency systems and legally required standby systems must be physically protected from fire or be fire-rated. This is often accomplished by using cables listed for use in fire-resistive construction, such as those meeting the requirements of UL 2196 or having a 2-hour fire-resistive rating.

Purpose

The goal is to ensure that the ATS can function during a fire, switching to the emergency power source and providing power to critical loads (fire pumps, emergency lighting, etc.). If the control wiring is destroyed by fire, the ATS may not be able to operate, defeating the purpose of the emergency system.2.

Health Care Facilities (NEC Article 517)

Health care facilities have stringent requirements for emergency power systems. Fire-rated wiring is typically required for emergency systems in these facilities.3.

High-Rise Buildings

Many local building codes require fire-rated wiring for essential systems in high-rise buildings.4.

Areas of Refuge

If the ATS control wiring passes through or serves an area of refuge, fire-rated cable may be required to ensure continued operation of systems in that area during an evacuation.5.

Specific Building Codes and Local Amendments

This is crucial! Many jurisdictions have amended the NEC or adopted separate building codes that impose stricter requirements. Always check your local building codes and amendments. Your drawing note may be refering to a local amendment.6.

Authority Having Jurisdiction (AHJ)

The AHJ (e.g., a local electrical inspector) has the final say. They can require fire-rated cable based on their interpretation of the code and the specific circumstances of the installation.

Key Considerations



Fire Resistance Rating

The 2-hour rating is significant. It indicates the cable's ability to withstand fire conditions for a specified duration. This rating must be appropriate for the fire resistance rating of the building's construction.

Cable Listing

Look for cables that are listed by a recognized testing laboratory (e.g., UL) for use in fire-resistive construction. Common listings include UL 2196 (Fire Resistive Cable) or cables with an equivalent fire-resistance rating.

Alternative Methods

While fire-rated cable is a common solution, other methods can achieve the required level of protection. This may include: Encasing the wiring in concrete. Using a listed fire-rated raceway system. Protecting the wiring with a listed fire-rated enclosure.

Type of Cable

Common fire-rated cables include MI (Mineral Insulated) cable and some specially designed fire-rated THHN/THWN conductors in a listed raceway system.

Why the Note on Your Drawing?

The note on your drawing likely stems from one of these reasons: The project involves an emergency system, legally required standby system, or a healthcare facility. The local building code mandates fire-rated wiring for ATS control circuits. The designer wants to provide an extra margin of safety and reliability. A previous similar project required it. The client specified it.

What to Do


Review the Project Specifications

Carefully examine the project specifications, particularly any sections related to electrical systems, emergency power, and fire protection.2.

Consult the Local Building Codes

Research the applicable building codes and any local amendments. Focus on sections related to emergency systems, standby power, and fire-rated wiring.3.

Contact the AHJ

If there is any ambiguity or uncertainty, contact the local electrical inspector or building department for clarification.4.

Communicate with the Design Engineer

Discuss the note on the drawing with the design engineer to understand the reasoning behind the requirement.

In Summary:

While the NEC doesn't universally require 2-hour fire-rated cable for all ATS control wiring, it is required in many situations, especially for emergency and legally required standby systems. The key is to understand the specific requirements of the project, the local building codes, and the AHJ's interpretation. Always err on the side of caution and verify the requirements before proceeding with the installation. Flag for review