This paper traces the development of Ontario’s cap lamp standard. Over the years, numerous Coroner’s Juries investigating fatal mine accidents have made recommendations with respect to underground lighting. As well, recommendations to improve mine lighting have been made by two Commissions, investigating mine safety in Ontario.

During the past few years, the performance of any cap lamp worn by miners involved in serious accidents, have been measured by the Mining Health and Safety Branch. Large variations in light output were found between and among cap lamp types. These variations have been attributed to the lack of quality control on the bulbs, design of the cap lamp head piece and in some cases, poor maintenance.

In 1986, a series of underground tests were conducted to establish the minimum light output from cap lamps required to visually identify loose ground. The results of these tests indicated that a cap lamp should produce a minimum peak illuminance of 1500 lux measured at 1.2 metres from the light source.

On May 30, 1987, Ontario became the first province in Canada to legislate the minimum amount of light required to visually assess ground conditions.