Generally, mounting a condenser disconnect directly on the condenser is permissible, but there are several factors to consider to ensure compliance with the National Electrical Code (NEC) and local amendments. Here's a breakdown

Potential Issues and Considerations (and corresponding NEC sections):
Accessibility (NEC 440.14)

The disconnect must be readily accessible. This means that it should be located within sight from the air-conditioning or refrigeration equipment, or be capable of being locked in the open (off) position. If the disconnect is mounted on top of the condenser and requires a ladder to reach it, it's not readily accessible. The intent is that the service technician should be able to turn the power off right at the equipment. Readily accessible means being capable of being reached quickly for operation, renewal, or inspections without requiring those to whom ready access is requisite to climb over or remove obstacles or to resort to portable ladders, and so forth.

Working Clearance (NEC 110.26)

You must maintain adequate working clearance around the disconnect. This includes sufficient space in front of the disconnect for a qualified person to safely operate and maintain it. The specific dimensions depend on the voltage and condition of the area. If the condenser is close to a wall, the space in front of the disconnect might be restricted.

Listing and Labeling (NEC 110.3(B))

The disconnect must be listed and labeled for its intended use and installed according to its listing. This means it has to be rated for the environment (e.g., outdoor use, weather-resistant). The mounting hardware must also be appropriate for the application.

Secure Mounting

The disconnect must be securely mounted to the condenser. The mounting method should be able to withstand vibration and weather conditions. Simply screwing it into thin sheet metal might not be sufficient. Consider using vibration-dampening mounts.

Conduit Entry/Strain Relief (NEC 314.17)

Proper strain relief is required for the wiring entering the disconnect. Conduit must be securely attached, and any flexible conduit should be adequately supported.

Protection from Physical Damage (NEC 110.27)

The disconnect must be protected from physical damage. If the condenser is in a location where it could be bumped or damaged, additional protection might be required.

Disconnect Type (NEC 440.12)

The disconnect must be rated for the application (e.g., horsepower rating for a motor). Typically, a non-fused disconnect is used, but some situations might require a fused disconnect.

Local Codes and Amendments

Local jurisdictions may have additional requirements or restrictions. Always check with the local electrical inspector or building department. They have the final say.

Good Practices



Use a NEMA 3R or 4X Enclosure

If the disconnect is outdoors, use a weather-resistant enclosure rated for the environment.

Mount on a Solid Part of the Condenser

Attach the disconnect to a structurally sound part of the condenser to minimize vibration and ensure a secure mount.

Use Vibration-Dampening Mounts

These will help prolong the life of the disconnect and reduce noise.

Properly Seal Conduit Entries

Use appropriate fittings to seal conduit entries and prevent moisture from entering the disconnect.

Labeling

Clearly label the disconnect to indicate which unit it serves.

In summary

Mounting the disconnect on the condenser can* be done correctly, but it requires careful consideration of the NEC and local codes. Accessibility, working clearance, secure mounting, and environmental protection are the key factors.

Recommendation:

Before installing a disconnect in this manner, consult with a qualified electrician and the local electrical inspector to ensure compliance with all applicable codes. They can assess the specific site conditions and advise on the best mounting method. Always err on the side of caution and prioritize safety. Flag for review