You're right to be concerned about running medium voltage cable through a drop ceiling in a parking garage. It's a potentially hazardous situation that requires careful consideration of the NEC. Here's a breakdown of why it's problematic and the relevant code sections

Why It's Problematic
Accessibility

Drop ceilings are generally considered easily accessible. This means unauthorized personnel could potentially come into contact with the medium voltage cable, even if it's in rigid conduit.

Safety

Medium voltage cable poses a significant shock hazard. A failure or damage to the cable within the drop ceiling could have catastrophic consequences.

Fire Hazard

If a fault occurs in the cable, it could ignite combustible materials in the drop ceiling.

Maintenance/Inspection

The location of medium-voltage cables in a drop ceiling would make visual inspection and maintenance very difficult.

Relevant NEC Code Sections & Considerations 300.37 Above Ground

This section addresses installation requirements for MV cables installed above ground, and would apply. It defers to other applicable articles.

399.11 Equipment Location. Section 399.11(A) states: Equipment shall be installed in suitable dedicated equipment rooms, vaults, or outdoor fenced or walled in enclosures, and shall be marked with a sign in accordance with 110.21 NEC 314.29 Junction Boxes and Pull Boxes to Be Accessible

While the cable might not have a junction box in the ceiling, this section highlights the general principle that electrical equipment should be accessible for maintenance and inspection. Running the cable above a drop ceiling makes it much less accessible than other alternatives.

NEC 110.26 Spaces About Electrical Equipment

While this might primarily apply to the termination points, the general concept of providing adequate working space around electrical equipment is relevant. Accessing and working on a medium voltage cable above a drop ceiling would be difficult and potentially unsafe.

Why It's Likely Not Permitted (or at least highly discouraged)

Based on the NEC and general safety principles, running medium voltage cable through a drop ceiling in a parking garage is highly unlikely to be permitted by an electrical inspector. Here's why: Not a Suitable Environment

Parking garages are not designed or intended for medium voltage equipment. They are considered areas with potential for physical damage, moisture, and other hazards.

Lack of Dedicated Space

Medium voltage equipment should be in a dedicated space that is not accessible to the general public. A drop ceiling is not considered a dedicated space.

Enforcement Authority

The local electrical inspector or Authority Having Jurisdiction (AHJ) has the final say. They are likely to reject this installation based on safety concerns and the intent of the NEC.

Alternatives and Recommendations1. Direct Burial

If the situation allows, direct burial of the cable is a much safer and more compliant option. Ensure you meet the burial depth requirements in the NEC.2.

Dedicated Conduit Bank

Encasing the medium voltage cable in a concrete-encased conduit bank that runs along the floor or ceiling of the parking garage would be a better option. This provides physical protection and containment.3.

Cable Tray System

A cable tray system, properly grounded and protected, could be used. But ensure it's a robust system designed for medium voltage cable and installed in a secure location away from potential damage.4.

Dedicated Shaft or Enclosure

The best option might be to create a dedicated shaft or enclosure for the medium voltage cable, separating it entirely from the public access areas of the parking garage.5.

Consult with the AHJ

Before proceeding with any installation, consult with the local electrical inspector (AHJ). They can provide guidance on acceptable methods and any local code requirements.

Important Considerations Engineering Review

A qualified electrical engineer should review the entire medium voltage installation to ensure it meets all applicable codes and safety standards.*

Safety Procedures

Strict safety procedures must be followed during installation and maintenance of medium voltage cables.

In summary, while your contractor may be looking for a quick solution, running medium voltage cable through a drop ceiling in a parking garage is a safety hazard and is unlikely to be compliant with the NEC. Explore alternative methods and consult with the AHJ to ensure a safe and code-compliant installation. Flag for review