Electrical process seal requirements in North American Electrical Codes

Both the National Electrical Code (NEC) [1] and the Canadian Electrical Code (CEC) [2] contain sealing requirements to prevent the migration of flammable fluids from travelling through wiring systems to non-hazardous locations. This paper will review the need for, the intent and the application of these code requirements. Case studies of incidents will be discussed to demonstrate that significant hazards exist, and how they are effectively mitigated by the code requirements. In addition, product standards can be used to meet the intent of the sealing requirements. CSA C22.2 No. 30 Explosion Proof Enclosures for use in Class I Hazardous Locations [3], and ANSI/ISA 12.27.01 Requirements for Process Sealing Between Electrical Systems and Flammable or Combustible Process Fluids [4] currently exist and IEEE PAR 1673 Requirements for Conduit and Cable Seals for Field Connected Wiring to Equipment in Petroleum and Chemical Industry Exposed to Pressures Above 1.5 kilopascals (0.22 psi) [5] is under development.