ETL SEMKO is part of Intertek Testing Services, Inc., the world's largest product and commodity inspection organization with 240 laboratories and 469 offices in 93 countries in North America, Europe and Asia. ETL SEMKO provides product safety testing and certification, EMC testing, product performance testing, and registration of quality management systems for a variety of industries such as medicine, HVAC, appliances, telecommunications, aviation, automation, semiconductors, building materials, energy generation systems, etc.

Any electrical, mechanical or electromechanical product with the ETL inspection mark indicates that it has been tested and meets the relevant industry standards. Each industry has different testing standards, so be sure to consult professionals for specific product requirements. The ETL inspection mark is widely used in cable products, indicating that the relevant tests have been passed.

In most parts of the United States, electrical product approval is mandatory. ETL refers to ETL Testing Laboratories Inc. ETL's listed products are recognized by "Authorities Having Jurisdiction" and can be considered "approved."