Yes, it is perfectly acceptable and common practice to run the line and load conductors for a dedicated AC circuit (or any AC circuit for that matter) in the same conduit.Here's why and considerations: NEC Compliance

The National Electrical Code (NEC) requires all conductors of the same circuit to be in the same raceway or cable. This includes the line (hot), neutral (if present), and ground. This is to minimize impedance, improve circuit performance, and enhance safety by ensuring a low-impedance fault path.

Inductance/Impedance

Separating the line and load conductors can create inductive loops, increasing impedance in the circuit. This can lead to voltage drop, overheating, and nuisance tripping of circuit breakers. Keeping them together helps cancel out magnetic fields, reducing inductance.

Fault Current Path

In the event of a fault, having all conductors in the same conduit ensures a low-impedance fault current path back to the source. This is crucial for quickly tripping the overcurrent protection device (OCPD) and minimizing damage and shock hazards.

Installation Simplicity

Using a single conduit is generally easier and cleaner than running multiple conduits.

Therefore, you should absolutely run the line and load conductors for your AC circuit in the same conduit between the junction box and the disconnect.Regarding your specific situation



Junction Box and Disconnect Relocation

Your plan to use a short nipple of conduit (under 24") between the junction box and the disconnect is fine. Make sure the junction box is properly sized for the number of conductors and connections it will contain, and that all connections are made securely.

Non-Fused Disconnect

The fact that the disconnect is non-fused is irrelevant to whether the conductors can be in the same conduit. The NEC rule applies regardless.

Wire Sizing

Ensure that the wire size and insulation type are appropriate for the load and the environment (e.g., temperature rating).

Grounding

Don't forget to include the grounding conductor in the conduit as well. The grounding conductor is essential for safety.

Conduit Fill

Make sure the conduit fill is within the limits specified by the NEC.

Type of Conduit

Ensure you are using an appropriate type of conduit for the application (e.g., EMT, PVC, etc.).

In summary: Your plan to use a single conduit for the line and load conductors of your AC circuit is correct and is in compliance with electrical codes. Ensure proper wire sizing, grounding, conduit type, and conduit fill. Flag for review