Cabling and wiring are critical to the safety. reliability and operability of chemical process facilities, especially in Hazardous (Classified) locations. The National Electrical Code (NEC), Article 500, provides the basic rules for electrical installations in locations where flammable gases or vapors may be present. There have been revolutionary changes in Article 500 in recent NEC Code Cycles. The European (or zone system) offers the option of meeting international standards, and offers significant advantages in chemical plants. Some chemical (and petroleum) companies have been using open wiring, drip loops, cabling systems instead of conduit. Cable systems are also very flexible and offer significant maintenance advantages.