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NFPA 70B Single-Line Diagrams and System Studies

NFPA 70B Chapter 6 Introduction

Ensuring the safety and reliability of electrical systems is a fundamental requirement in industrial and commercial facilities. NFPA 70B outlines best practices for electrical maintenance, including single-line diagrams and system studies, to mitigate risks, maintain compliance, and optimize system performance.The Gimba software is tightly integrated with NFPA 70B requirements and not only integrates an interactive and dynamic one-line / single-line diagram, but also allows you to track the status, frequency, and last completed system studies. 

NFPA 70B System Studies and Single-Line Diagrams / 1-line diagrams

According to NFPA 70B, “System studies shall be completed in accordance with this chapter” (NFPA 70B 6.1.1). These studies are crucial for understanding electrical system performance and ensuring compliance with safety standards. Additionally, “Single-line diagrams shall be maintained in accordance with this chapter” (NFPA 70B 6.1.2), emphasizing the importance of accurate documentation for system analysis.

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    NFPA 70B Single-Line Diagrams

    Single-line diagrams serve as the primary reference for system studies. They must be kept legible, accurate, and up to date:

    • “Single-line diagrams shall be maintained in a legible condition” (NFPA 70B 6.2.1).
    • “Single-line diagrams shall be kept accurate” (NFPA 70B 6.2.2).
    • “Single-line diagram shall indicate the date of the last revision” (NFPA 70B 6.2.3).
    • In cases where these diagrams are unavailable, “the facility or equipment owner shall be responsible for providing an equally effective means of obtaining the necessary information” (NFPA 70B 6.2.4).

    See how the Gimba NFPA 70B Software platform makes handling your system studies and one-line requirements as easy as clicking a button.

    Gimba Dynamic Single-Line Diagrams One-line Diagrams

    The Gimba advanced NFPA 70B Software platform dynamically creates a hierarchical view of your current feeds from and and feeds to information. This view can be clicked on and traversed through. This allows the user to go from one device to another and be able to see on a table/phone/computer the relationship between all devices. Also, you can use this to see what devices would be affected if a given line needed to be shut down for maintenance. 

    NFPA 70B Short-Circuit Studies

    Frequency: Every 5 Years

    Short-circuit studies identify potential system vulnerabilities and ensure proper protective device coordination:

    • “Where a short-circuit study does not exist, one shall be created, as necessary to support the arc-flash risk assessment and equipment evaluations” (NFPA 70B 6.3.1).
    • These studies must be updated whenever system changes impact results (NFPA 70B 6.3.2).
    • “The short-circuit study shall be reviewed for accuracy at intervals not to exceed 5 years” (NFPA 70B 6.3.3).
    • “The most recent study shall be made available to the EMP coordinator” (NFPA 70B 6.3.4).
    • If updates are made, “an electrical equipment rating evaluation shall be completed for the equipment within the scope of the study” (NFPA 70B 6.3.5).

    NFPA 70B Coordination Studies

    Frequency: Every 5 Years

    Coordination studies ensure the effectiveness of protective devices in minimizing system disruptions:

    • “A coordination study shall be created as necessary to support risk assessments and the intended system design goals” (NFPA 70B 6.4.1).
    • “The coordination study shall be updated when changes occur in the electrical distribution system that could affect the results of the study” (NFPA 70B 6.4.2).
    • “The coordination study shall be reviewed for accuracy at intervals not to exceed 5 years” (NFPA 70B 6.4.3).
    • “The most recent study shall be made available to the EMP coordinator” (NFPA 70B 6.4.4).
    • Updates must include “review and verification of overcurrent protective devices and equipment ratings” (NFPA 70B 6.4.5).

    NFPA 70B Load-Flow Studies

    Frequency: Every 5 Years

    Load-flow studies ensure power distribution efficiency and identify potential voltage drop concerns:

    • “If a load-flow study is needed to allow maintenance to be performed, the load-flow study shall be updated when changes occur that could affect the results of the study” (NFPA 70B 6.5.1).
    • “The load-flow study shall be reviewed for accuracy at intervals not to exceed 5 years” (NFPA 70B 6.5.2).
    • “The most recent study shall be made available to the EMP coordinator” (NFPA 70B 6.5.3).

    NFPA 70B Reliability Studies

    Frequency: Every 5 Years

    Reliability studies help minimize unplanned outages by identifying potential weak points in the electrical system:

    • “A reliability study shall be conducted as necessary on critical or important facility electrical systems to identify equipment and circuit configurations that can lead to unplanned outages” (NFPA 70B 6.6.1).
    • “Spare parts shall be monitored and inspected periodically to ensure that they will be available when needed” (NFPA 70B 6.6.2).
    • “The reliability study shall be reviewed for accuracy at intervals not to exceed 5 years” (NFPA 70B 6.6.3).
    • “The study shall be kept current and revised whenever a significant change to the electrical system has been made” (NFPA 70B 6.6.4).

    NFPA 70B Arc-Flash Study (Incident Energy Analysis)

    Frequency: Every 5 Years

    Incident energy analysis evaluates the potential hazards associated with arc-flash events:

    • “The incident energy analysis shall be updated when changes occur in the electrical distribution system that could affect the results of the analysis” (NFPA 70B 6.7.1).
    • “The analysis shall be reviewed for accuracy at intervals not to exceed 5 years” (NFPA 70B 6.7.2).
    • “The most recent study shall be made available to the EMP coordinator” (NFPA 70B 6.7.3).

    NFPA 70B Electrical Maintenance-Related Design

    Electrical maintenance-related design studies aim to mitigate risks during maintenance activities:

    • “Where a recognized hazard presents an increased risk during maintenance, a study shall be conducted to develop design options that could be implemented to reduce risk” (NFPA 70B 6.8).

    References

    National Fire Protection Association (NFPA). (2023). NFPA 70B: Recommended Practice for Electrical Equipment Maintenance. NFPA.

      Gimba and NFPA 70B