Technical information

Organisations currently recognised by OSHA as NRTL:

(the list may change; please refer to OSHA web site:

http://www.osha.gov/dfs/otpcal/nrtl/index.html

Applied Research Laboratories, Inc. (ARL)

Canadian Standards Association (CSA) (also known as CSA International)

Communication Certification Laboratory, Inc. CCCL)

Curtis-Straus LLC (CSL)

Electrical Reliability Services, Inc. (ERS) (also know as Conformity Services and

formally as Electro-Test, Inc. (ETI))

Entela, Inc. (ENT)

FM Global Technologies LLC (FM) (also know as FM Approvals and formally as

Factory Mutual Research Corporation)

Intertek Testing Services NA., Inc. (ITSNA) (formally ETL)

MET Laboratories. Inc. (MET)

NSF International (NSF)

National Technical Systems. Inc. (NTS) SGS

U.S.Testing Company, Inc. (SGSUS) (formally UST-CA)

Southwest Research Institute (SWRI)

TUV America, Inc. (TUVAM)

TUV Product Services GmbH (TUVPSG)

TUV Rheinland of North America, Inc. CTUV)

Underwriters Laboratories Inc. (UL)

Wyle Laboratories, Inc. (WL)

3. Main reference texts

The National Electrical Code, already mentioned, sets a series of manufacture and

safety requirements for the installation of components and electrical equipment.

It is defined as an "open and consensus-based code” and it ensures that every new

or revised requirement reflects the current progress of technology.

The NEC also covers installations in dangerous environments (explosive

atmosphere). Establishes a series of “rules”:

■ mandatory rules (actions specifically required or prohibited)

■ permissive rules (permitted but not required actions)

■ explanatory material (references to other standards, informative notes)

Normally the NEC rules are more restrictive than OSHA rules, but the opposite

may also be true.

INTRODUCTION TO NORTH AMERICAN STANDARDS