It is possible to ignite combustible gases or vapors either directly from an arc or spark at the electrical equipment or from the heat generated by the electrical equipment, so extraordinary care must be taken when installing electrical equipment in these areas.
Jim Dollard has an extensive background in codes and standards. If you have a query about the National Electrical Code (NEC), Jim will help you solve it. Questions can be sent to email@example.com. Answers are based on the 2014 NEC. Previous use of gray conductors