Okay, let's break down the requirements for running Class 1 dimming control cable in free air from a device box to a lighting fixture, specifically considering your mention of Lutron DVSTV dimmers and 0-10V control. It's good you're thinking about code compliance before you install it.

Key Considerations and NEC Sections



Type of Cable

The most important factor is the type of cable you're using. You need a cable that is specifically listed and rated for free-air applications and for the voltage and environmental conditions it will be exposed to.

Common Options (with caveats)



Low Voltage Lighting Cable

This is the most appropriate type of cable to use.

Type CL3

Class 3 Cable

Type CM

Communications Cable

THHN/THWN

Individual THHN/THWN conductors are not suitable for exposed runs without additional protection. They are intended for use in conduit.

MC (Metal Clad Cable)

MC cable is allowed to be run in free air in certain applications, provided it is supported properly and the environment is suitable. However, it's often overkill for low-voltage dimming control and more expensive than other options.

NM/NMC Cable

NM cable (Romex) is generally not permitted for exposed runs unless specifically allowed by the NEC (e.g., certain framing situations in dwelling units). NMC is a possibility.

TC-ER (Tray Cable - Exposed Run)

TC-ER cable can be used in free air, but is generally heavier and more expensive than necessary for low-voltage dimming control.

Instrumentation Cable

It is possible that the cable is instrumentation cable, which often is rated for free air runs.

Separation of Power and Low-Voltage

This is a critical area. Even if your dimming control cable has a 600V rating, you cannot generally run it in the same raceway or cable assembly with line-voltage power conductors unless specific conditions are met.

NEC 725.136 (Separation from Electric Light, Power, Class 1, Nonpower-Limited Fire Alarm Circuit Conductors, and Medium-Power Network-Powered Broadband Communications Cables)

This is the governing section. It states that Class 2 and Class 3 circuit conductors must be separated from other circuits.

(A) Separation From Electric Light, Power, Class 1, and Nonpower-Limited Fire Alarm Circuit Conductors

Exception No. 1 to 725.136(A) is most applicable. It allows Class 2 and Class 3 circuits to be installed with power conductors if a barrier is installed between the two. The barrier needs to be permanently installed and identified as such.

(D) Conductors of Different Circuits in the Same Cable, Enclosure, or Raceway



(1) Two or More Circuits

725.136(D)(1) discusses the conditions where a class 2 or 3 circuit is in the same raceway, cable, or enclosure. This is generally not allowed unless specific conditions are met.

In Summary

The easiest and best approach is to run your low-voltage dimming control cable separately from any power conductors. This avoids the need for barriers and complex calculations.

Support

All cables must be adequately supported and secured. This is crucial for safety and preventing strain on the connections.

NEC 300.11 (Securing and Supporting)

This section addresses the general requirements for securing and supporting wiring methods.

NEC 330.30 (MC Cable)

This section addresses the securing and supporting for MC cables.

Listing and Labeling

Ensure the cable you use is listed and labeled by a nationally recognized testing laboratory (NRTL) like UL or ETL. The labeling should clearly indicate the cable's type, voltage rating, temperature rating, and suitability for the intended application.

Local Amendments

Always check with your local electrical inspector for any specific requirements or amendments to the NEC that may be in effect in your jurisdiction.

Specific to DVSTV Lutron Dimmers (0-10V Dimming)

DVSTV dimmers control lights using a 0-10V DC signal. This signal is a Class 2 or Class 3 circuit according to the NEC. This is important because Class 2 and Class 3 circuits have specific wiring and separation requirements.

How to proceed


Identify Your Cable

Determine the exact type of cable you intend to use. Get the manufacturer's specification sheet. Post this in your follow up. We can better help.2.

Dedicated Run

Ideally, run the low-voltage dimming control cable in its own run, separate from the power wiring. This is the simplest and most code-compliant solution.3.

Proper Separation

If you absolutely must run the dimming cable alongside power conductors, use a cable assembly that provides a permanent barrier between the power and low-voltage conductors, or install a physical barrier within the enclosure.4.

Support

Secure the cable at appropriate intervals using cable ties, straps, or other listed supports.

Example Scenario (Assuming Appropriate Cable)

Let's say you are using CL3 or CM rated cable (after confirming it's suitable for your application). You can run that cable in free air, properly supported, from the device box containing the Lutron DVSTV dimmer to the lighting fixture, as long as it is kept separate from any line-voltage power conductors.

Important Warning



Never assume! Always verify the suitability of the cable and the installation method with the manufacturer's specifications and the NEC. If you're unsure, consult with a qualified electrical inspector or licensed electrician. Electrical work can be dangerous, and improper installations can lead to fire or shock hazards.

To give you the best advice, please provide



The exact type of cable you plan to use (manufacturer and part number would be ideal). A detailed description of the installation environment (indoor/outdoor, dry/damp/wet location, temperature extremes, etc.). A sketch of the proposed cable run (showing the route and how it will be supported).

I hope this is helpful! Let me know if you have any more questions. Flag for review