Zone 0 (hazardous area)
An area in which an explosive gas-air mixture is continuously present or present for long periods.
Source: Rules and Regulations for the Classification of Mobile Offshore Units, Part 7, Safety Systems, Hazardous Areas and Fire, June 2013, Lloyd’s Register, Global Standards
Place in which an explosive atmosphere consisting of a mixture with air of flammable substances in the form of gas or vapour is present continuously or for long periods or frequently.
Source: IEC 60079-14:2013, Explosive atmospheres – Part 14: Electrical installations design, selection and erection, Edition 5.0, November 2013. Global Standards