The ANSI Z535 Standard for safety signs, labels, tags, and barricade tapes contains nearly 300 pages of technical information in six sections; some of which are integral to the others, and some not relevant to applications in the electrical utility industry. This can make the task of designing your safety signs, labels, and tags challenging and time consuming. And the cost of just purchasing the standard is in excess of $500. In this blog I have broken down the five key design elements in an understandable way in order to hopefully allow you to assess your existing designs, and draft new designs for conformance.

Overview of the standard

ANSI (Z535) is an American standard that sets forth a system for presenting safety and accident prevention information. It’s a voluntary standard that is revised every 4-5 years, and that becomes mandatory when it is incorporated by reference into codes and regulations your utility must stay in compliance with. Pretty much all codes and regulations in the US incorporate all or part of Z535 where safety/hazard identification markings are required. Those most relevant to the Electrical Utility Industry include OSHA and the NESC.

Essentially Z535 is a design guide that includes elements such as color, symbols, message content, layout format, and font. Z535 attempts to not only promote uniformity, but also increase the recognition effectiveness of the safety/hazard message. The effectiveness of all of the critical design elements has been established under controlled tests and/or experience and logic of industry and safety experts. I get questions from utility standards and safety engineers that they mistakenly presume are addressed by Z535. An example would be, “How many signs does ANSI specify I need on my substation fence enclosure?”  Again however, Z535 is a design guide and provides little or none in the way of decision guidance for specific physical application use. Requirement guidance in these areas is typically provided through relevant code/regulations such as OSHA or the NESC.

Key Design Elements


Z535.1 defines a measurable window of tolerance for the specific safety colors.munsell-coordinates-for-safety-red The brighter, more vivid colors such as Safety Red, Orange, Yellow, and Blue are utilized primarily in the signal word header panel at the top of the safety/hazard sign. Black is utilized primarily with the worded message lettering and safety symbol pictogram.

The word message lettering can be black on a white background or white on a black background, depending on which is considered more legible in the application. The standard doesn’t provide specific guidance towards what scheme would better suit specific applications, and so that consideration is left to the posting utility to determine. Text/background scheme is generally most relevant to making the sign outline more conspicuous against the mounting surface. In my opinion and in Electromark’s experience, black text on a white background is the most effective in outdoor environmental applications where shadow, light, and visual patterns of varied objects interact.


Colors specific to the chosen header signal word are used exclusive to other colors within the signal word panel. White lettering on a Safety Red background is used for DANGER, Black lettering on a Safety Orange background is used for WARNING, Black lettering on a Safety Yellow background is used for CAUTION, and italicized white lettering on a Safety Blue background is used for NOTICE.

! RED and YellowThe safety alert symbol (exclamation mark within an equilateral triangle) is always incorporated in the signal word panel with the hazard alert signal words DANGER, WARNING, and CAUTION. The safety alert symbol is not used with NOTICE, safety instruction, or safety equipment location signs. The signal word header panel is to contain only the signal word and safety alert symbol.

DANGER, WARNING, and CAUTION are hazard related signal words used where there is the potential for personal physical injury. NOTICE is used to indicate information considered important, but not hazard-related. It is important to understand the level of hierarchical risk priority the standard associates and assigns to these words.

4 Safety Headers with Definitions

The standard does not provide guidance towards specific physical location or equipment applications where a given hazard word may be appropriate, but only which hazard word should be used relevant to the level of hazard as determined by the user/poster of the sign.

Type style, justification, and size

Type Style

Serif - Sans SerifZ535 directs the preferred use of Sans Serif typeface. The use of mixed case is specified where only the first letter of the first word in a sentence is capitalized because it has been demonstrated to be easier to read. A single word or phrase such as “HIGH VOLTAGE” can be set in all upper case to provide emphasis.

Text Justification

Left aligned, ragged right text alignment is specified because it aids in readability, forming a vertical alignment that allows the eye to more easily jump to the next line of text. Again, a short, one line phrase can be centered for emphasis.Left Justified vs Centered

Type Size

Text size is relevant to reading distance. Safe viewing distance is that determinedLetter Height ANSI Z535.2 necessary by the posting utility for the reader of the safety sign to be far enough away from the hazard to remain safe while reading it, and be able to take appropriate evasive action in order to avoid it. Z535 provides a chart of letter heights determined necessary to achieve a given minimum safe viewing distance.

Message Content

The standard suggests providing and breaking the word message into 3 components; an avoidance action statement, a hazard description statement, and a consequence statement. Examples are as follows:

Avoidance Action: Do not dig!
Hazard Description: Buried electrical cables
Consequence: Contact by excavation equipment may result in death or serious injury

The experiential knowledge of the intended audience and physical barrier control to the hazard can be taken in to account when drafting the word message or considering whether all of the content elements are necessary. For instance, the interior components of a locked padmount equipment cabinet might only need the energized exposed components identified with the safety message; “HIGH VOLTAGE”; since only trained workers with an understanding of the hazard would have access and would be working on those components. On the other hand a hazard message on the outside of the cabinet intended to warn the general public should contain all three elements, since that audience can access that physical environment and would not be expected to be knowledgeable of the hazards it contains.

Pictogram Symbols

Man-ZapZ535 encourages the use of effective safety symbol pictograms, and provides guidelines for their development. Guidelines include elements such as standardization of the depiction of the human figure, application and design of the prohibited action circle/slash, placement, color and surround shapes, etc. Effective safety symbol pictograms employ the characteristics of legibility (viewer’s ability to visually distinguish the key elements of a symbol), simplicity (no unneeded detail or decoration), and comprehensibility (the symbol is likely to be understood as intended).

The standard specifies that the symbol pictogram be compatible with the written message. There are four types of safety-related messages that pictograms can illustrate: the existing hazard, mandatory actions, prohibited actions, and information. Safety symbol pictograms aid in quick identification of the hazard, especially among speakers whose primary language is other than that which the written message is communicated in.

Electromark Expertise

We purchase each new revision of the ANSI Z535 Standard and perform a thorough review of all changes so that Electromark can be a trusted adviser resource to our customers. In fact, I keep all the sections of the standard on the desktop of my computer and probably access and research something in it almost weekly. I also consult with industry expert safety contacts when questions with interpretations arise. Our graphic arts design staff is intimately familiar with the design elements of the standard, and serves as the front line in making sure that your signs, labels, and tags conform to the critical design elements of Z535. As a service to our customers, we encourage you to reach out to us to review your old designs and recommend and make necessary design changes. If you require a design review, contact your Electromark representative.

Example images from ANSI Z535-2011