National Electrical Code – A basic guide to equipment marking

NFPA 70®: National Electrical Code®

Basic guide to equipment marking

The white paper serves as a detailed guide to understanding how equipment intended for hazardous (classified) locations are marked according to the NEC 500 series and other relevant standards. It emphasises:

• The critical nature of accurate marking for safe installation and operation.
• The distinction between U.S. and international systems, particularly around Class/Division vs. Zone models.
• The importance of using certified equipment with proper markings to comply with NFPA 70, OSHA, and NRTL requirements.

The paper covers the following topics:

1. Regulatory Framework and Context
2. Labelling and Marking
3. Class/Division/Group/Temperature Classification
4. Class/Zone (AEx)
5. Testing and Certification Bodies
6. Example Label Analysis
7. Intrinsic Safety and Entity Parameters