In my experience, the project engineer of record should ultimately be responsible for ensuring the correct disconnect switch is specified, but they should work closely with the elevator vendor to determine the requirements.

Here's a breakdown of why and how this typically works: Project Engineer's Responsibility (EOR)



Overall System Coordination

The EOR is responsible for the overall electrical system design, ensuring that all components, including the elevator disconnect, meet the project's requirements, the NEC (National Electrical Code), local codes, and safety standards.

Building Load Calculations

The EOR has the overall responsibility of building load calculations and ensuring sufficient service capacity.

Integration with Building Systems

The EOR is responsible for coordinating the elevator power requirements with the building's electrical distribution system, including panelboard selection, overcurrent protection, and feeder sizing.

Code Compliance

The EOR ensures all aspects of the electrical design comply with the latest editions of the NEC and any local amendments.

Documentation and Record-Keeping

The EOR is responsible for documenting the electrical design, including the disconnect switch specifications, on the project drawings and specifications. This documentation becomes part of the permanent record for the building.

Elevator Vendor's Responsibility



Equipment Power Requirements

The elevator vendor is the expert on their specific elevator equipment. They should provide the EOR with precise information on the elevator's:

Full Load Amps (FLA)

This is the normal operating current of the elevator motor(s).

Locked Rotor Amps (LRA)

This is the inrush current the motor draws when starting. It's significantly higher than FLA.

Voltage

The operating voltage of the elevator equipment.

Number of Motors

This is for traction elevators.

Any Special Requirements

This could include harmonic filtering, power quality requirements, or specific grounding needs.

Disconnect Switch Location and Type

The vendor is responsible for informing the engineer of the type of disconnect switch needed. This is usually a fused disconnect.

Code and Standard Compliance

Elevator manufacturers are responsible for ensuring their equipment meets relevant safety codes and standards (e.g., ASME A17.1). They'll know any specific disconnect requirements related to those standards.

The Process - How It Works in Practice


Elevator Vendor Provides Information

The project engineer requests detailed power requirements from the elevator vendor early in the design process. A complete submittal package, including the equipment specifications, are given to the engineer.2.

Engineer Sizes the Disconnect

Based on the elevator vendor's data, the engineer:

Calculates the Minimum Ampacity

The engineer uses the FLA, LRA, and NEC guidelines (e.g., Article 430, Article 620) to determine the minimum required ampacity for the disconnect switch. Often, NEC dictates to use 125% of the nameplate rating of the equipment to size the conductors and overcurrent protection device.

Selects the Disconnect Switch

The engineer selects a disconnect switch with an appropriate ampacity rating, voltage rating, short-circuit current rating (SCCR), and enclosure type (NEMA rating) to suit the environment.

Specifies Fuses

The engineer specifies the appropriate fuses for the disconnect switch. This involves considering the motor's FLA and LRA to ensure proper protection against overloads and short circuits while allowing for motor starting.

Coordinates with Building Systems

The engineer ensures the disconnect switch is properly connected to the building's electrical distribution system, taking into account feeder sizing, overcurrent protection, and grounding.3.

Engineer Documents on Drawings

The engineer includes the disconnect switch specifications (manufacturer, model number, ampacity, voltage, fuse type, enclosure type) on the electrical drawings.4.

Vendor Reviews and Approves

As part of the shop drawing process, the elevator vendor reviews the electrical drawings to confirm that the specified disconnect switch meets the requirements of their equipment and any relevant elevator codes.

Why the EOR Must Be Involved



Liability

The EOR holds professional liability for the correctness and safety of the overall electrical design.

Coordination

The EOR is the only one with the full picture of how the elevator connects to the rest of the building's systems.

Code Expertise

The EOR is responsible for interpreting and applying the NEC and local codes correctly.

Key Takeaways

The elevator vendor provides the essential power requirements for their equipment. The project engineer uses that information to select and specify the appropriate disconnect switch, ensuring code compliance and integration with the building's electrical system.* Close communication and collaboration between the elevator vendor and the EOR are crucial for a successful project.

In summary, the project engineer should ultimately specify the disconnect switch, but they cannot do so effectively without the elevator vendor providing accurate and complete power requirements. Always document the communication and the basis for the selection in case questions arise later. Flag for review