The National Electrical Safety Code® (NESC®) occasionally references other standards. For example, ANSI Z535.1-1991 through ANSI Z535.5-1991 inclusive are referenced many times within the NESC. Most of these references are made in a NOTE: following a rule. Rule 015D explains that a NOTE: indicates material provided for information or illustrative purposes only. When a standard is referenced in a NOTE:, compliance with the standard is not mandatory.
One of the references to ANSI® Z535.1-1991 through ANSI Z535.5-1991 inclusive is within a rule. Rule 411D states that “all warning signs and tags required by Part 4 shall comply with the provisions of ANSI Z535.1-1991 through ANSI Z535.5-l991 inclusive.” In the very next sentence, Rule 411D requires “permanent warning signs shall be displayed in conspicuous places at all entrances to electric supply stations, substations, and other enclosed walk-in areas containing exposed current-carrying parts.” In this case, where a reference is made within a rule, compliance with the standard is mandatory.
So, What is ANSI Z535?
ANSI Z535 is the American National Standard for Safety Signs, Labels and Tags. It is the standard “for the design, application, and use of signs, colors, and symbols intended to identify and warn against specific hazards and other accident prevention purposes.” The standard consists of five publications labeled ANSI Z535.1-1991 through ANSI Z535.5-1991.
ANSI Z535.2-1991 is the standard for environmental and facility safety signs. The warning signs spoken of in Rule 4llD would be considered “facility safety signs.” For a safety sign to be effective in alerting people of a hazard, the message must be easily recognizable and highly conspicuous. To achieve this, ANSI Z535.2-1991 recommends that safety signs be designed with three elements.
The first element is a signal word to get the person’s attention, i.e., DANGER, WARNING, CAUTION or NOTICE. The signal word designates the degree or level of safety alerting.
The word DANGER should only be used in an imminently hazardous situation which, if not avoided, will result in death or serious injury. This signal word is the one to use on a sign located inside an enclosure containing exposed line parts as recommended by Rule 381G2 for pad-mounted equipment. The hazard is life threatening and immediate.
The word WARNING should only be used in a potentially hazardous situation which, if not avoided, could result in death or serious injury. This signal word is the one to use on a sign located on the outside of the entrance to an enclosed walk-in area containing exposed line parts as required in Rule 411D. The hazard is life threatening but is not immediate. There is a door between the person and the hazard.
The word CAUTION should only be used in a potentially hazardous situation which, if not avoided, may result in minor or moderate injury or property damage. This is not a life-threatening situation. This signal word is the one to use on a sign alerting people that a passageway does not have 7 foot head room as required by Rule 112B or a low ceiling in a parking garage.
The word NOTICE should only be used to indicate a company policy directly or indirectly related to safety of personnel or protection of property. This signal word is the one to use on the sign that informs personnel that “Hard hats are required in this area” or “Check oil when refueling your vehicle.”
The colors used to display the signal word must comply with ANSI Z535.1-1991, i.e., white letters on red for DANGER, black letters on orange for WARNING, black letters on yellow for CAUTION, and white letters on blue for NOTICE.
The second element is a symbol or pictorial to promote greater or more rapid understanding. The use of symbols and pictorials is very important in getting the message across since the general population’s reading and comprehension skills vary. ANSI Z535.3-1991 covers the requirements for safety symbols. Symbols should be tested to insure that the people to whom the sign is directed understand what the symbol means. Symbol comprehension varies with location. A symbol that passes the test in New York may not pass the test in Florida. A suggested procedure for evaluation of symbols is included in the standard.
The third element is the message text. The message should identify the hazard, i.e., High Voltage, the location of the hazard, i.e., Inside, how to avoid the hazard, i.e., Keep Out! and the probable consequences of not avoiding the hazard, i.e., Can shock, burn or cause death. This example is the message you might use on an electrical hazard WARNING sign. ANSI Z535.2-1991 also gets into letter style, letter size, viewing distance, sign placement, illumination and the use of bilingual signs.
ANSI Z535.4-1991 covers product safety signs and labels. These are the kind of labels you would expect to see on your new chain saw. ANSI Z535.5-1991 covers accident prevention tags for temporary hazards. The blocking tags required by Rule 442E and 444C must comply with ANSI Z535.5-1991 because they are in Part 4.
ANSI Z535 has just recently been revised (1998). The significant change in the new edition is the addition of a safety alert symbol, an exclamation point inside a triangle, to the left of the DANGER, WARNING and CAUTION signal words involving personal injury. The safety alert symbol should not be used on a CAUTION sign intended to prevent property damage.