The ignition probability of circuits is a decisive criterion for the testing and the assessment of the intrinsic safety. This is why it is planned to perform in this program, a corresponding number of ignition tests with different circuits. The ignition probabilities are determined and compared. As the description of the spark test apparatuses in IEC 60079-11, Annex B, allows an "interpretation margin", this comparison also generates information about possible systematic and random error sources of the procedure provided in the standard.

In the program, the ignition probability of twelve different circuits is compared by ignition tests with the aid of a spark test apparatus in accordance with IEC 60079-11. The simple circuits are designed in accordance with the above-mentioned standard. In addition to what is required by the standard, circuits which show a dynamic behaviour will be included in the comparison.

To guarantee the objective performance and homogeneity of the tests, and to eliminate any subjective expectations with regard to the test results, the circuits as well as the power supply will be pre-determined and specified by the coordinator. The twelve circuits, including the power supply, are permanently installed in a "black box" (Test Box "SI") and cannot be changed during the complete program.

For each one of the twelve circuits, the ignition probability is determined with a gas mixture in accordance with IEC 60079-11. It is planned to provide so many contactings per circuit until 20 ignitions have been reached. The overall effort for the performance of program thus results from the achievement of a total of 240 ignitions for all tested circuits of Test Box "SI".