You're correct. The NEC does not explicitly require fire alarm circuits to be run in dedicated conduit in most cases. Your understanding of a dedicated circuit is accurate.Let's break down where you might have gotten this idea and what the NEC actually says

Why the Confusion?
Habit and Best Practices

Many electricians, especially those with experience in critical life safety systems, develop habits and best practices that go beyond the minimum requirements of the NEC. Dedicated conduit for fire alarm circuits has been a common practice, even if not strictly mandated by the code. It's a way to: Ensure circuit integrity: Separate conduit protects the fire alarm wiring from physical damage. Minimize interference: Reduces the likelihood of electromagnetic interference from other circuits. Simplify troubleshooting: Makes it easier to identify and access fire alarm wiring. Prevent accidental modifications: Other trades are less likely to accidentally damage or modify fire alarm wiring if it's in its own conduit.

Local Codes and Amendments

It's possible that a local jurisdiction (city, county, or state) might have amendments to the NEC that do require dedicated conduit for fire alarm circuits. Always check local codes!

Specific System Requirements

Certain types of fire alarm systems or specific installations might require dedicated conduit due to manufacturers' instructions, engineering specifications, or the requirements of the Authority Having Jurisdiction (AHJ). These requirements would be in addition to the NEC.

Past NEC Editions

While I don't recall a blanket requirement for dedicated conduit in recent editions, older versions of the code might have had language that was interpreted that way.

What the NEC 2023 Does Say



Article 760: Fire Alarm Systems

This is the primary article governing fire alarm systems.

760.41 Power Sources



(B) Branch Circuit Requirements. For a 120-volt branch circuit to supply fire alarm equipment, it shall be a dedicated branch circuit. (2) Identification. A disconnecting means in compliance with 760.41(B)(1) shall comply with either of the following: (1) Be identified as FIRE ALARM CIRCUIT. (2) Be colored red. General Wiring Methods (Chapter 3)

Article 300 covers general requirements for wiring methods. Some of these provisions might indirectly affect your fire alarm wiring, such as:

300.3(C)(1) Single Raceway

Where all of the following conditions apply, conductors of different systems shall be permitted in the same raceway, cable, or enclosure: (1) The conductors are insulated for the maximum voltage of any conductor in the raceway, cable, or enclosure. (2) All conductors are AC or DC. (3) The grounded conductors of the systems are insulated. (4) All equipment grounding conductors are insulated.

Key Takeaways


Dedicated Circuit is Required

The NEC does require a dedicated branch circuit for the 120V fire alarm system power supply. This means no other loads can be connected to that circuit.2.

Dedicated Conduit is Generally Not Required

The NEC does not generally require fire alarm circuits to be in dedicated conduit. You can run them in the same raceway as other circuits, if you comply with the conditions outlined in 300.3(C)(1).
3.

Check Local Codes

Always, always, always check with your local AHJ. They may have amendments to the NEC or local ordinances that require dedicated conduit.4.

Follow Manufacturers' Instructions

If the fire alarm system manufacturer specifies dedicated conduit, you must follow their instructions.5.

Consider Best Practices

Even if not required, dedicated conduit may still be a good practice for the reasons outlined above.

In summary: You are correct in that the 2023 NEC does not explicitly mandate dedicated conduit for fire alarm circuits in most general installations. Make sure you have the dedicated circuit, and check local codes and manufacturer's instructions before proceeding. Flag for review