This is a complex question with no simple yes or no answer. The requirements of Article 708, Critical Operations Power Systems (COPS), in the National Electrical Code (NEC) can be demanding and costly to retrofit into an existing building. Here's a breakdown of the considerations

Key Considerations:
Extent of the Requirements

Article 708 dictates the installation, operation, and testing of a dedicated power source and distribution system (COPS) intended to supply power to loads that are critical to the operation of essential services for public safety, emergency management, national security, or economic security.

The NEC is not retroactive

Generally, the NEC applies to new installations and substantial modifications/renovations. However, the authority having jurisdiction (AHJ) has the final say. They may require some level of compliance if the discovery of the vital infrastructure status triggers a requirement for enhanced reliability.

708.4 Performance of Essential Electrical Systems

The COPS system is required to automatically supply power to the essential electrical system loads (as per 708.4(A)) within the time specified in Article 700 or 701 depending on the loads being supplied. This performance criteria would require the system to have the ability to automatically start, transition, and supply power within seconds of a loss of power.

708.10 Physical Separation

This is a major hurdle in existing buildings. The COPS must be physically separated from other electrical systems. This typically involves dedicated raceways, wiring, and distribution equipment. This is often the most expensive and disruptive part of a retrofit.

708.12 Survivability

Wiring methods used in COPS must be rated for the physical environment. This could involve fire-rated raceways and wiring, protection against water, etc.

708.14 Surge Protection

COPS must be protected against surges.

708.16 Grounding

The system grounding is critical and must adhere to Article 250, including dedicated grounding electrodes.

708.20 Overcurrent Protection

Requirements for selective coordination are crucial to ensure only the faulted circuit trips, not upstream breakers.

708.22 Automatic Transfer Equipment

COPS often requires automatic transfer switches (ATS) that are specifically rated and tested for COPS applications.

708.30 Testing and Maintenance

Regular testing and maintenance are mandatory to ensure reliability.

AHJ Interpretation

The local AHJ's interpretation of how strictly Article 708 must be applied in this specific retrofit situation is paramount.

Possible Scenarios and Solutions


Full Rewire (Less Likely but Most Compliant)

If the AHJ insists on full compliance, a complete rewire of the critical circuits as a dedicated COPS according to Article 708 may be required. This is expensive and disruptive.2.

Generator Plus Selective Upgrades (Most Likely and Practical)

A generator set that meets the performance and reliability requirements of Article 708 (start time, fuel supply, etc.) can be installed. The existing critical circuits are connected to the generator through new automatic transfer switches (ATSs) rated for COPS. Selective upgrades are performed:

Physical Separation

This is likely the most challenging. The AHJ might allow exceptions if the existing wiring is already in conduit and in a relatively protected environment. They may accept a compromise of improved fire-stopping and physical barriers instead of completely separate raceways.

Survivability

Improve fire protection around the critical circuits.

Surge Protection

Install COPS-rated surge protection devices (SPDs).

Grounding

Improve the grounding system, ensuring proper grounding electrode connections.

Selective Coordination

Replace overcurrent devices (circuit breakers) to achieve selective coordination on the critical circuits.

Monitoring and Annunciation

Install monitoring systems to provide alarms and status information about the COPS system.3.

Risk Assessment and Engineering Judgement (Possible but Requires AHJ Approval)

Conduct a thorough risk assessment to identify the specific vulnerabilities of the existing system. Develop an engineered solution that mitigates the most critical risks, focusing on reliability and performance. Present this solution to the AHJ for approval, demonstrating that it provides an acceptable level of safety and reliability even if it doesn't strictly adhere to every requirement of Article 708. This could involve a combination of upgraded components, enhanced monitoring, and improved maintenance procedures.

Steps to Take


Engage a Qualified Electrical Engineer

This is crucial. An engineer with experience in critical power systems and Article 708 can assess the existing system, develop solutions, and work with the AHJ.2.

Consult with the AHJ Early

Discuss the situation with the local electrical inspector before making any changes. Get their input on what level of compliance they expect. This will save time and money in the long run.3.

Comprehensive Assessment

A thorough electrical system assessment is necessary. This includes reviewing existing drawings, conducting load studies, and inspecting the condition of the wiring and equipment.4.

Develop a Plan

Based on the assessment and discussions with the AHJ, develop a detailed plan that outlines the proposed upgrades and modifications.

In conclusion, a full rewire is unlikely. The more probable path is to install a code-compliant generator set coupled with strategic upgrades to the existing electrical system that prioritizes enhanced reliability and performance. The key lies in a collaborative approach with the AHJ and a qualified electrical engineer to arrive at a solution that balances compliance, budget, and the specific needs of the vital infrastructure facility. Flag for review