EU Member States were obliged by regulation (EU No 994/2010 of the European Parliament and of the Council of 20th October 2010 concerning measures to safeguard security of gas supply) to analyze their gas system and to carry out a stress test: every member state must analyze the consequences of a disruption of the single largest gas infrastructure (e.g. the largest gas feed-in point).

Member states only passed the test if the capacity of the remaining infrastructure proved to be able to satisfy the total gas demand during a day of exceptionally high gas consumption.

The test is also referred as the N – 1 test, in which N is the number of feed points and ‘1’ is the failure of the largest feed in point. If member states did not pass the test, they were obliged to improve their gas infrastructure or take other measures, like appropriate market-based demand-side measures