Recent results of low-frequency (<6 kHz) magnetic field noise measurements at underground coal mines are presented. A comparison of these results to measurements made 35--40 years ago suggests that the magnetic field noise has increased substantially since this period of time. The ambient noise level is an important factor in the operation of through-the-earth (TTE) communications systems, and the data presented herein are a consideration in the design of future TTE systems. IEEE

The Mine Improvement and New Emergency Response Act (MINER Act) of 2006 (PL 109-236, 2006) established the Office of Mine Safety and Health, functioning as the Office of Mine Safety and Health Research (OMSHR) within the National Institute for Occupational Safety and Health (NIOSH) and provided authority for awarding contracts related to the development and implementation of new mine technology and equipment. The OMSHR external contracts program was formed in accordance with the MINER Act and has since issued more than 150 contracts focused on worker health and safety. Initial funding for this program was provided by the United States Congress through two emergency supplemental appropriations and was focused on emergency oxygen supply, communications and tracking, and refuge chambers (also referred to as refuge alternatives). Since the MINER Act, Congress has continued to fund the program through the annual NIOSH mining appropriation.

This paper provides a suitability determination of international standards for evaluating electrical and electronic systems and line powered apparatus as an alternative to the Mine Safety and Health Administration (MSHA) criteria for two-fault intrinsic safety (IS) approval. The primary issue is to demonstrate that international equipment evaluation standards will provide at least the same level of protection for miners as the MSHA requirements. The secondary issue is to identify additional benefits that may be derived from the use of the "entity concept" in the approval process, such as potential cost savings and an easier and quicker path for the introduction of new technology.

The Mine Improvement and New Emergency Response Act of 2006 (MINER Act Public Law 109-236) was passed by Congress in response to three major underground coal mine accidents in the United States that claimed the lives of 19 miners. The Act resulted in substantial changes in the underground coal industry relative to the use of technology for mine escape, rescue, disaster response and other areas where the lack of these technologies contributed to the fatalities caused by these tragedies. This year marks the 10th anniversary of the MINER Act, which makes it an opportune time to reflect on the events that led to its passage, the changes that have been made since then, and the work that remains to be done.

Recent mine disasters in the U. S. exposed various inadequacies and gaps in mine-safety technology. Congress responded to these tragedies by enacting the Mine Improvement and New Emergency Response Act of 2006 (MINER Act), which resulted in the most significant change to mine-safety laws in 30 years. To help meet the requirements of the MINER Act and to help eliminate future tragedies, the National Institute for Occupational Safety and Health initiated aggressive research programs for developing new, and enhancing existing, mine-safety technologies. A major research emphasis addressed the lack of postaccident communications, which surfaced as a critical deficiency in some disasters. As a result, three communications approaches emerged as viable technologies-enhanced leaky-feeder, wireless-mesh, and medium-frequency systems. This paper describes the operation, application, advantages, and disadvantages of each system, as well as the challenges associated with underground wireless communications.