The continuous monitoring systems developed for health and safety provisions in underground mines have always been a deep concern in mining activity, since this is one of the most dangerous work activities in the world. All mining activities must follow strict regulations that pose an increased responsibility for the design and implementation of novel technologies aiming to enhance both the workers’ and equipment’s safety in underground mines. Coal mines are some of the most dangerous, with high risk of explosion due to pit gas; therefore, we propose the use of visible light communication for local wireless transmission and optical fiber for remote-cabled transmission. We address, in this article, a complete system comprising real-time personnel tracking and environmental methane measurement, as well as the transmission of data, with a detailed explanation of the complete system and technical description with practical solutions applicable for industrial use.

The main topic of this paper is to analyse the approach to fault – finding, tests and maintenance regarding on what shall and shall not be done in an installation in hazardous area from the point of view of the explosion – protection safety. For a fault it is usual to be investigated by following a logical routine. This is one possible ways of proceeding developed from good engineering practice and experience in general terms. The test equipment for use in hazardous area will be either certified or uncertified. The maintenance is regarding in this paper from the point of view of SR EN 60079 – 17 starting from general requirements.

SR EN 60079 is a series of standards for the use of equipment in explosive atmosphere that covers a wide range of considerations for them, as well as the definition of various classifications of hazardous areas. An important section of the series specifically covers the repair, overhaul and modification of equipment. This is different from the maintenance of equipment, unless the repair and overhaul cannot be separated from the maintenance. SR EN 60079-19 edition 2020 establishes the general principles of repair, revision, and modification, which are common to all explosion-proof equipment, with additional clauses to provide instructions relevant to certain types of protection. Assuming that repairs and revisions are carried out using good engineering practices and details of the certificate, then the final equipment is considered to comply with the original standard and the manufacturer's specifications. Where these specific data are not available, the equipment can be simply described as having been repaired in accordance with SR EN 60079-19 and the relevant standards for which the equipment was designed.