Mark C. Ode, was the lead engineering instructor at the Underwriters Laboratories Inc. in the Research Triangle Park, North Carolina UL University and Knowledge Services for five years, was a member of UL’s Regulatory Services Department for ten years, and was Lead Engineering Instructor for UL. He has written monthly NEC articles for Electrical Contractor Magazine since 2000. He was co-author of the Stallcup 2008 NEC Changes Book, co-author of the Stallcup 2008 Journeyman Electrician’s Study Guide, co-author of the Stallcup’ 2008 Master Electrician’s Study Guide, and co-author of Cengage-Delmar’s Electrical Raceways and Other Wiring Methods—Sixth Edition. He was a Senior Electrical Specialist for the National Fire Protection Association and staff liaison and secretary to the NFPA Electrical Equipment in Chemical Atmospheres Committee. He was the Executive Secretary for the NFPA Electrical Section and editor of the Electrical Section news bulletin, Current Flashes. Prior to joining NFPA, Mr. Ode worked for over 27 years as a licensed electrician and a licensed electrical contractor.