Both SIMTARS and Londonderry are currently participating in the international certification scheme for hazardous location equipment, known as the International Electrotechnical Commission IECEx Scheme which will give the labs the right to test and certify equipment, at an international level. The timing, therefore, of any negative press about any one of the two agencies would not be opportune.

There are differing views on where responsibility for IS equipment starts and ends. The Coal Mines Regulation (Electrical - Underground Mines) 1984, places sole responsibility on the shoulders of the mine electrical engineer. Under duty of care, if he thought his mine had a problem with safety, he would have to do something about it. But any decision by the electrical engineer is likely to be based on paperwork which says whether or not a system is safe. And certification documentation for IS power supplies does not say whether or not they have been subjected to spark-gap testing.

“What I am worried about,” said one source, “is equipment out there that has been approved using, what would appear to be, flawed testing procedures. It really begs the question, how long has that methodology been used and what equipment is out there, even above ground or in other underground mines, that might be prone to failure?”

Londonderry said measures were being taken to address the issue, including re-examination of all power supply units it has certified and investigation of international testing procedures. It is also engaging the services of a world-renowned IS expert.

Meanwhile, local coal mines are left with many unanswered questions.