Role of Testing and Certification Bodies

The electrical safety system in North America depends on an interplay of different organizations and publications. All of them have to be carefully coordinated for the system to work.

Publications include laws, regulations, codes, standards, and recommended practices. Organizations that are essential to electrical safety include standards-developing organizations, electrical installation companies, electric utilities, code enforcement groups (electrical inspectors), and testing and certification bodies. This article discusses the role of testing and certification bodies, particularly Intertek Testing Services’ ETL SEMKO division, and how they relate to other essential players in the electrical safety system.

Intertek Testing Services is a global independent testing organization. The author is an employee of Intertek Testing Services N A, Inc., ETL SEMKO, frequently called simply ETL SEMKO. In this article, ETL SEMKO will be used for the company name.

Codes and Standards

Legislature enacts laws intended to protect public safety; then regulatory bodies promulgate regulations that translate the legislature’s general intent into specific rules that can be followed

Private-sector standards-developing organizations (SDOs) create codes and standards for electrical products and installations, in response to regulations and other indications of public needs for standards.

The most widely used publication relating to electrical safety is the National Electrical Code (NEC), sponsored by the National Fire Protection Association (NFPA). The NEC is an installation guide, which has been adopted into law in many jurisdictions. The committee that writes the NEC has members representing a broad range of interests, including certification bodies. Several certification bodies send representatives to the National Electrical Code Committee, including ETL SEMKO, which presently has 10 members on the committee.

The NEC covers only electrical installations. It is essential that materials used for these installations, such as conduit and cable, and products connected to the wiring system, such as electric machines, meet certain minimum criteria for safety; thus there are also product standards. Products that connect to a building’s wiring system need to be compatible with the electric system, so product standards have to be compatible with requirements of the Code.

To ensure that compatibility, SDOs that sponsor product standards, such as IEEE, ISA and particularly UL, maintain membership on the National Electrical Code Committees.

The product standards that are sponsored by these SDOs are also written by technical committees representing varied interests. A large majority of electrical product safety standards are UL standards. The technical committees responsible for UL standards are called Standards Technical Panels (STPs). ETL SEMKO has about 25 employees on one or more UL STPs.


Just as the NEC is enforced by authorities having jurisdiction, such as electrical inspectors, product standards are enforced by testing and certification bodies, such as ETL SEMKO. When a product is listed (as defined in NEC Article 100), authorities have reasonable assurance that it conforms to an appropriate product standard, and that standard is compatible with the NEC and other applicable installation codes. This is the fundamental reason that Section 90.7 of the Code indicates that internal wiring and the details of construction of listed equipment does not need to be examined for conformity to code requirements at installation.

Another significant point in 90.7 is that the laboratory, i.e., the certification body, should be properly qualified. There are many organizations that qualify or accredit testing laboratories and certification bodies. The main qualifying body, and the one with enforcement powers in the workplace, is the U. S. Occupational Safety and Health Administration (OSHA). OSHA has qualified 19 nationally recognized testing laboratories (NRTL) as of this writing. Some NRTLs are OSHA-accepted for hundreds of product standards; others, for just a few. The NRTLs’ scopes of acceptance may be found on OSHA’s website,

ETL SEMKO Services in Product Safety

ETL SEMKO offers a number of services that relate to safety of electrical products and systems. Most NRTLs offer similar, but not identical, services. Some of the services that may be of interest to readers are described here.

ETL Listing
This is the basic conformity assessment service and mark offered by ETL SEMKO. ETL Listed products have been evaluated and found in conformance to appropriate identified standards. Following the initial product evaluation, ETL SEMKO conducts periodic unannounced examinations of listed products, commonly referred to as follow-up inspections. A product that is ETL Listed will bear an ETL Listed Mark, the word “Listed,” a control number, and a clear indication — the number, full name, or shortened name — of the basic standard used to evaluate the product. ETL Listed products are identified in the Directory of Listed Products, which may be viewed on line

ETL Classification Service
This is essentially the same as listing service, except that classification is used where there are clear limitations to the range of risks covered by the applicable standard. For example, the Electrical Standard for Industrial Machinery, ANSI/NFPA 79-1997 addresses electrical risks associated with industrial machines, but does not address physical injury risks of moving machines. Obviously, the physical injury risks can be considerable. That is the main reason ETL SEMKO makes the distinction. The certification mark for classified products hears the words, “ETL Classified,” but is otherwise identical to the listing mark.

ETL Recognized Component
Recognized components are only suitable for use as component parts of products that are covered by other standards. A recognized component needs the surroundings of an end-use product, and frequently needs particular testing in the end product. Recognized components are not suitable as electrical construction material, nor as utilization equipment, by themselves. The ETL Mark on a component bears the words, “Recognized Component,” so that authorities having jurisdiction will know the labeled item does not fully conform to a recognized standard. Other elements of the recognized component mark are as previously described for a listed product.

ETL Field Evaluation and Labeling
This service, normally performed to satisfy the needs of authorities having jurisdiction, applies only to apparatus that is already installed and operable. ETL field evaluation is conducted using applicable product standards and installation codes. The evaluation follows the standard as closely as practical, given the limits of testing on-site, where conditions are largely uncontrolled.

ETL SEMKO will always make a good-faith effort to notify the authority having jurisdiction in advance of a field evaluation, although successful contact is not guaranteed.

Where the apparatus is found to effectively conform to the applicable requirements, ETL SEMKO will apply a “Field Evaluated” label, which identifies ETL, but does not bear the word, “Listed,” nor does it identify a standard. Field evaluation labels are serialized, and ETL SEMKO maintains records that connect each label with the item to which it was originally applied.

Limited Production Certification
This program is used where small numbers of products will be produced in a short time period. The product evaluation process is the same as for ETL Listing; however, there is no ongoing follow-up service, due to the limited time and production quantity. LPC-based products do not appear in the ITS Directory of Listed Products, but the certification mark is identical to the ETL Listed Mark.

CB Test Certificate
ETL SEMKO, along with a few other certification bodies in the US, is a member of the IEC’s scheme for mutual acceptance of test results, known as the CB Scheme. Participants in the CB Scheme evaluate products against international (IEC) standards, and issue certificates to attest to their conformance. Other CB Scheme member organizations agree to accept the certificates, with minimal review of the actual products, and grant product certification based on the CB Test Certificates. A CB Test Certificate itself is not a certification, but evidence that the tested product conforms to the standard.

Field Examination
On request, ETL SEMKO will inspect a product’s construction in the field, against construction requirements of a standard. In this case, ETL SEMKO issues a findings report to its client. There is no label, certificate, or similar instrument left at the site.

Impact of World Trade

World trade has affected SDOs and certification bodies in ways large and small, including the CB Scheme previously mentioned. Standards organizations, including UL, are adopting international standards, with “national differences,” such as those driven by the NEC.

ETL SEMKO and a few other certifiers in the U.S. have joined not only the CB Scheme, but also a companion program for apparatus used in hazardous (classified) locations, known as the IEC Ex Scheme.

There is another international program known as the Full Certification Scheme (FCS). CB Scheme depends on mutual acceptance of test results, while FCS depends on a certification body in one member country accepting another’s certification (listing) in its entirety. The Full Certification Scheme is comparatively new, and worldwide participation is rather limited, as of this writing, but is expected to grow.


Intertek Testing Services’ ETL SEMKO division is an active participant in the electrical safety system, as a certification body, as a testing laboratory, and as a contributor to standards development. ETL SEMKO may be contacted on line

William Fiske
William T. Fiske is director of engineering for Intertek Testing Services, ETL SEMKO Americas, a post he has held since 1997. Mr. Fiske has been employed by ITS since 1977. He is a member of ASQ, CSA, IEEE, ISA, and NFPA. He serves on NFPA's National Electrical Code Committee as principal member of CMP-1 and alternate member of CMP-14, as well as the Committee on Electrical Equipment in Chemical Atmospheres. Mr. Fiske serves on the ISA committee SP12 (Instrumentation in Classified Locations) and 5 of its subcommittees, and on 14 UL Standards Technical Panels (STP). Fiske is a licensed professional engineer, registered in Louisiana, New York and Texas.