What is Warnock Hersey?

Warnock Hersey is a mark used in North America to indicate compliance with building codes and safety standards on construction sites. The symbol is commonly found on wood fire-rated doors.

The mark is also commonly referred to as WH-ETL. Previously the ETL mark had been a separate indicator of electrical safety, but the two marks were merged into one in 2013. The mark is owned by Intertek and indicates that this company has tested and certified the equipment in question. Intertek is an OSHA-recognized national testing laboratory in the United States and is also accredited in Canada and by the International Accreditation Service.