NEC 645.10: One of the Most Ignored Electrical Code Sections

[jar546]

The National Electrical Code (NEC) Section 645.10, which focuses on disconnecting means for information technology (IT) rooms, is often overlooked despite its critical importance for safety and compliance. This section mandates that an approved method must be in place to disconnect power to all electronic equipment within an IT equipment room or designated zones within the room. Additionally, a similar disconnect method must be available for all dedicated HVAC systems serving the room or designated zones, ensuring that required fire/smoke dampers close during an emergency. The disconnecting means must adhere to either 645.10(A) or 645.10(B).

One of the primary reasons this section is frequently ignored is due to the complexity and perceived inconvenience of implementing these safety measures. However, adherence to 645.10 is crucial for ensuring the safety of personnel and the protection of equipment in the event of a fire or other emergency. The section is clear in its requirements but often underestimated in its necessity.

645.10(A) Remote Disconnect Controls

Under this subsection, several specific requirements must be met:

1. Emergency Access: Remote disconnect controls must be located in approved, easily accessible locations to authorized personnel and emergency responders in case of fire. This ensures that power can be swiftly cut off in an emergency, reducing the risk of electrical fires and enabling safer evacuation.
2. Disconnect Identification: The remote disconnect means for controlling the power to electronic equipment and HVAC systems must be grouped and clearly identified. This grouping and identification streamline emergency procedures, allowing quick and accurate response. A single control means for both systems is permissible, simplifying the process further.
3. Fire/Smoke Zone Isolation: When multiple zones are created within an IT room, each zone must have an approved means to contain fire or smoke within that zone. This zoning helps to prevent the spread of fire and smoke, protecting other areas and minimizing damage.
4. System Operation Continuity: Additional means to prevent the unintentional operation of remote disconnect controls are allowed. This provision ensures that disconnect controls are not accidentally triggered, which could disrupt operations and cause unnecessary downtime.

Typically, the circuits supplying IT equipment and HVAC systems are controlled through separate disconnecting means. However, these can be operated via a single remote control, such as a push button. The disconnecting means must sever each circuit's connection from its power source and close all required fire/smoke dampers. This setup ensures a comprehensive response to emergencies, shutting down systems and containing potential hazards efficiently.

The Exception:
It is important to note that these requirements do not apply to installations complying with Article 685, which pertains to Integrated Electrical Systems.

 

[wwhitney]

The National Electrical Code (NEC) Section 645.10, which focuses on disconnecting means for information technology (IT) rooms,

To clarify, Article 645 is an optional article; you are never required to comply with 645.10 on its own and can just ignore Article 645 if you like. What Article 645 does is to provide you with additional allowances for wiring methods beyond the usual Chapter 3 methods (see 645.4) if you provide certain additional safety features. If you're happy to hook up everything with Chapter 3 wiring methods, you don't need to provide a 645.10 disconnecting means.

Cheers, Wayne

 

[jar546]

To clarify, Article 645 is an optional article; you are never required to comply with 645.10 on its own and can just ignore Article 645 if you like. What Article 645 does is to provide you with additional allowances for wiring methods beyond the usual Chapter 3 methods (see 645.4) if you provide certain additional safety features. If you're happy to hook up everything with Chapter 3 wiring methods, you don't need to provide a 645.10 disconnecting means.

Cheers, Wayne

The use of wiring methods allowed by Article 645 depends on the ITE room being constructed according to the requirements specified in NFPA 75. Article 645 includes specific wiring method installation requirements for ITE rooms, such as those for wiring methods in the space beneath the raised floor used for environmental air, which are less strict than the requirements in Chapter 3 for similar spaces.

However, these modified requirements can only be applied if the ITE room construction and equipment meet all six conditions outlined in 645.4. If any of these six conditions are not met, the wiring methods in the ITE room must comply with the relevant requirements of Chapter 3, Parts I and II of Article 725 for signal wiring, and Parts I and V of Article 770 for optical fiber cabling.