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.
National Electrical Safety Code and NESC are the
registered trademarks of the Institute of Electrical and
Electronics Engineers. ANSI is a registered trademark of the
American National Standards Institute. ANSI Z535 is a
publication of the National Electrical Manufacturers
Association (NEMA).
David C. Young is a Senior Engineer with
Conectiv of Wilmington, Delaware, where he has been working
with and teaching the NESC for over 27 years. He is a member
of the NESC Interpretations Subcommittee and an alternate on
the NESC Overhead Lines Clearances Subcommittee. He is also a
member of the ANSI Z535 committee.
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