Chapter 4 Wiring Systems
73
Copyright Goodheart-Willcox Co., Inc.
utility company requires that permits be obtained
and the work be done by or under a licensed electri-
cian before they will furnish power. Contact the elec-
trical inspector or power company supervisor for
information pertaining to permits and licensing.
Equipment
Testing Agencies
There are many recognized testing agencies
throughout the U.S. and Canada. Each of these
agencies, known as a nationally recognized testing
laboratory (NRTL) tests materials and equipment
submitted to them by electrical material manufac-
turers. If the materials and equipment submitted
measure up to the testing agencies’ expectations,
the items are listed as suitable for electrical installa-
tion. In addition, the product will be labeled with a
recognized mark to identify the testing agency that
approved the product. See Figure 4-2.
Almost all reputable manufacturers of electrical
materials and equipment submit their products
for testing. Products that are not listed should be
avoided. In fact, it violates the NEC to use an unlisted
product when there are listed ones available.
The most widely known testing agencies
are Underwriters Laboratories (UL), Canadian
Standards Association (CSA), and Intertek Testing
Services NA (formerly ETL). Products listed by
these and other testing agencies are sure to be well-
constructed and safe. See Figure 4-3.
Occupational Safety and
Health Administration
(OSHA)
The Occupational Safety and Health
Administration (OSHA) is the agency with the
responsibility of creating and enforcing health
and safety standards to protect persons in all
occupations within the U.S. OSHA is an agency
within the United States Department of Labor.
The regulations can be obtained by contacting
the Offi ce of Information Services, OSHA, U.S.
Department of Labor, Washington, D.C. These safety
regulations are often more detailed than those of the
NEC and, in some instances, supercede the NEC
rulings. When in doubt, consult the AHJ.
Underwriters Laboratories
Intertek Testing Services NA (Formerly ETL)
Canadian Standards Association
Figure 4-2. These are a few of the marks that indicate
approval by an NRTL.
Learn More
Visit the Occupational Safety and Health
Administration (OSHA) website for more elec-
trical-related OSHA standards, hazards informa-
tion, and news articles.
nationally recognized testing laboratory (NRTL): A
recognized testing agency that tests materials and equip-
ment submitted to them by electrical material manufac-
turers to verify that the item is suitable for electrical instal-
lation. NRTL is an OSHA designation given to approved
testing facilities.
Occupational Safety and Health Administration (OSHA):
An agency within the United States Department of Labor
that is responsible for creating and enforcing health and
safety standards to protect persons in all occupations
within the U.S.