Strategies for electrical labeling and documentation

Electrical equipment must be correctly labeled and documented. Follow these strategies to achieve enhanced safety and documentation.


This article has been peer-reviewed.Learning objectives

  •  Understand codes, standards, and requirements for labeling and signage.
  • Learn best practices for documenting and labeling electrical equipment.
  • Offer solutions and tips for electrical distribution system documentation.

Figure 1: This flowchart can help the designer or facility personnel determine which signal word to choose and the color codes assigned to each hazard condition. Courtesy: IMEGConsistent documentation is an important safety strategy for electrical engineers and facility operators. Operating procedures for electrical gear should be readily understood by facility staff, and methods to implement labeling should be considered by the engineers during design. Methods of documentation of arc flash data and overcurrent protection device (OCPD) settings affect the speed at which facility operators can respond to fault conditions. Additionally, electrical distribution configuration and fault data should be part of a living document that facility personnel and designers maintain as a cooperative effort.

Why electrical equipment must be labeled

Strategies for labeling and documentation are partially driven by applicable code requirements. An obvious location to look for requirements is NFPA 70E-2015: Standard for Electrical Safety in the Workplace, Article 130.5(C)(2)(D). This section specifies the type of labeling information required and includes available incident energy and personal protective equipment (PPE) categories. These requirements are echoed in NFPA 70-2017: National Electrical Code (NEC), Article 110.16. Both of these sections address the first reason to provide descriptive equipment labels: for personnel safety. Additional labeling requirements are listed in 2017 NEC Article 110.21. These requirements apply to field-applied markings and signage. ANSI Z535.4-2011: Product Safety Signs and Labels is referenced in NEC Article 110.21 and provides specific guidelines for signage. Engineers should ensure that the labeling requirements listed in the design specifications are not in conflict with those specified by the ANSI standard. ANSI distinguishes the meaning behind several common words and when it is appropriate to use them.

Figure 2: Example of a permanent equipment label. Courtesy: IMEGAn example of a required “DANGER” label is in 2017 NFPA 70, Section 110.34(C), which requires rooms containing equipment with a nominal voltage greater than 1,000 V to include a sign at the entrance labeled “DANGER—HIGH VOLTAGE—KEEP OUT.” The details of this signage can be referenced in ANSI. The flow chart depicted in Figure 1 is derived from ANSI Z535.4-2011, Figure E2. This flow chart can help the designer or facility personnel to determine which signal word to choose and the color codes assigned to each hazard condition.

OSHA Standard 29 CFR 1910.144-2007, Safety color code for marking physical hazards, defines safety color codes for marking hazards. Red is specified for fire protection equipment, danger, or “stop.” Yellow is specified for caution and marking physical hazards associated with falling or tripping. OSHA Standard 29 CFR 1910.145-2013, Specifications for accident prevention signs and tags, includes specifications for signs and tags to prevent accidents and directs the facility to inform personnel about the intent of color codes and verbiage. OSHA references ANSI for color codes and adds the definition of a biohazard.

Additional signage guidelines in ANSI Z535.4-2011 include text justification and text arrangement, order of information, grammar, text font and size, letter spacing and line spacing, and multilingual arrangement. Commercial software is available for development of signage that complies with OSHA, ANSI, and ISO regulations. Table 1 references ANSI Z535.4-2011 and illustrates recommended font sizes based on viewing distance.

Figure 3: Example of an automatic transfer switch (ATS) label. Courtesy: IMEGThe guidelines for font sizing are directly related to the distance at which the message is to be considered legible. If the message is describing a hazardous condition, it should be legible from outside the hazardous area. An unfavorable reading condition may be caused by poor lighting or poor viewing angles. These are important aspects for designers and facility personnel to apply. Designers should specify lighting levels sufficient for identifying hazards and reading signage.

The second reason for labeling is informational. While the safety labels are intended to identify hazards, informational labels assist facilities in understanding how the equipment is connected and provide instructions for proper operation. Informational labels may be code-required, at the request of the facility, or as specified by the designer for enhanced understanding. A common application for informational signage is to identify the panel name and circuit number on a receptacle faceplate as required by NEC 2017 Article 517.19. The receptacle faceplate color is required to identify a connection to an emergency branch per NFPA 99-2015: Health Care Facilities Code, Article Details of receptacle cover-plate labels are specified by the design engineer and should be coordinated with the naming configuration and label type desired by the facility. Additionally, the type of material used for the label should be suitable for the environment, as noted in 2017 NEC Article 110.21(B)(3). Engraved cover plates are an option when environmental conditions can cause failure of label adhesives.

Labels for panel/circuit information are not limited to receptacles. Any panel or piece of equipment should have a label to identify where power can be disconnected (see Figure 2). Lockout-tagout procedures should be considered when deciding labeling details. Equipment labeling may include voltage, source-panel name, and source-panel location (if elsewhere in the facility). Mechanical equipment labeling also should include type and location of control. Transfer switch labels should identify both sources of power (see Figure 3). Transformer labels should include panel names for both primary and secondary connections. Panelboards with feedthrough conductors should include labels identifying what other panels or loads are affected by outages. Junction boxes should include panel and circuit numbers. Labels such as these will increase safety for shutdowns and allow facility staff to quickly react to outages. Compliance with UL 969-2017: Standard for Marking and Labeling Systems should be specified for adhesive labels.

Figure 4: Photo of a laminated emergency power riser diagram located in a main emergency power supply system (EPSS) electrical room. Courtesy: IMEG

In some cases, color coding is a requirement. For instance, NEC-2017 Article 760.41 requires circuit breaker handles to be red in color when serving fire alarm panels and power supplies. The informational color codes used may conflict with the ANSI color codes to indicate hazards. OSHA 29 CFR 1910.145 supports the concept of using red color coding for fire alarm conduit and junction box covers. When used, raceway and junction box identification should combine both color and text to match a campus or facility standard. Colored conduit is an affordable way to provide quick identification of the associated system in the field. If a color-coding standard does not yet exist for a facility, designers can discuss implementing a new standard with the current projects. These discussions help build relationships between designers and facility personnel, an effort that benefits both parties.

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