Power April 2022 Intl - 14

O&M
Get in the Zone for Safety in
Hazardous Areas
Hazardous area solutions from foreign
suppliers may not be tested to the same
standards as those in general use across
the U.S. It's essential to understand
there is tremendous liability to use those
technologies at a power plant or other industrial
facility.
Knowing the rules and regulations
when using foreign-manufactured equipment
in hazardous locations is critical.
So, what are the rules, what certifications
are necessary, and how do you tell
if equipment is safe for your application?
Hazardous location classified areas
contain flammable gas, liquids, or vapors;
combustible dusts; or easily ignitable fiber
and flyings. When any one of these is combined
with an oxidizer and ignition source,
the result may be an explosion or fire.
In North America, equipment meeting
relevant hazardous area location certifications
first must meet ordinary location
requirements. These " ordinary " standards
include but are not limited to:
■ UL 94-VO standard for flammability.
■ UL 489 for molded case circuit breakers.
■ UL 50 and NEMA 250 standards for
electrical enclosures.
■ UL 1581 standard for electrical wires,
cables, and flexible cords.
Hazardous areas solutions from overseas
may not be tested to ensure they
meet the general ordinary location standards
in America. When organizations
decide to use technology from outside
North America, there are the National
Electrical Code (NEC) and Occupational
Safety and Health Administration (OSHA)
exceptions to consider, and liability exists
if equipment is not certified to North
American standards.
Primer on Zone Equipment
Certification
The Zone method has become a worldwide
accepted practice for classifying
hazardous location classified areas. The
International Electrotechnical Commission
System for certification to standards
relating to equipment for use in
explosive atmospheres (IECEx System)
lists 62 countries that are full members,
and an additional 26 as associate
members. Many countries have
their own directives and certification
14
What if an AEx-Zone or Division certified
technology isn't available? The NEC
Article 500.8(A) addresses this possibility
and indicates that the suitability of
equipment is determined by one of the
following:
■ Equipment listing.
■ Evidence of equipment evaluation
from a qualified testing lab or AHJ.
1. The Zone method of equipment marking
enables operators, including power plant
workers, to better understand hazardous location
classified areas. Courtesy: Eaton
requirements for equipment approvals
within their borders.
The Zone method (Figure 1) dates to
1996. It was first introduced by the National
Fire Protection Association (NFPA)
with NEC Article 505. It allows for parallel
classification in the traditional NEC
Article 500 Division system.
In this division system, Zone terminology
was used as the international
system for classification of hazardous
locations containing flammable gases,
liquids, or vapors; combustible dust; or
ignitable flyings, which divided classified
areas into three segments: Zone 0, Zone
1, or Zone 2 for gases/vapors, and Zone
20, Zone 21, or Zone 22 for combustible
dust and ignitable flyings.
Today, Zone-rated equipment still requires
certification of ordinary location
requirements in the U.S. The AEx marking,
developed by the American National
Standards Institute (ANSI) and International
Society of Automation (ISA), ensures
that Zone equipment conforms
with hazardous location requirements
and the general ordinary location American
safety standards. As such, the AEx
symbol is a critical marking requirement
within the Zone material nomenclature.
The AEx marking per NEC article 505.9
and Article 506.9 certifies the equipment
has been produced to American standards-conforming
with both general
standards for ordinary locations and hazardous
area requirements.
The Authority Having Jurisdiction (AHJ)
and qualified testing labs have an essential
role. The AHJ can approve equipment
when there is sufficient safety data. Further,
if equipment is listed by a qualified
lab, then the internals of the equipment
do not need to be inspected, except to
look for problems, changes, or damage.
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■ Evidence acceptable to the AHJ like a
manufacturer's self-evaluation or owner's
engineering judgment.
A manufacturer's self-certification and
owner's engineering judgement must
be carefully reviewed and only be considered
when the decision-maker is fully
confident that ordinary safety standards
have been achieved. This evidence must
also be accepted by the AHJ.
Further, OSHA provides
additional
guidance and requirements for product
allowance. OSHA 29 CFR 1910.399 defines
equipment acceptable for hazardous
environments if it is:
■ Determined safe by a nationally recognized
testing lab.
■ Inspected by another federal agency,
or by a state, municipal, or other local
authority responsible for enforcing
occupational safety provisions of the
NEC and found in compliance with the
NEC.
■ Determined to be safe (for its intended
use) by the manufacturer, based on
test data that the employer keeps and
can provide for inspection purposes.
Zone Method Rated Equipment
The OSHA and NEC allowances permit
a product to be approved for installation
without third-party testing by a nationally
recognized testing lab (NRTL). OSHA
lists 19 NRTLs on its website, including
UL, CSA, ETL-Intertek, and FM.However,
and importantly, both the OSHA and NEC
language indicate the general rule is that
equipment should be tested and listed
by an NRTL-unless these avenues have
been exhausted.
When thinking about electrical equipment
without testing by an NRTL, it's
important to consider:
■ Does the state or municipality where
equipment is being installed have
requirements only allowing for the
POWER | April 2022
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Power April 2022 Intl

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