The size of a fuel break in a top of the ridge with several different configurations of slope is studied on this work.
Laboratorial tests were performed to simulate the same geometric conditions of a fire occurred in centre of Portugal and that was extinguished by itself due to the special configurations of slope and geometric barrier to fire spread that correspond to a fire break. Based on this fire other configurations were tested to measured their impact on the probability of the fire crossing the geometric barrier of a gap.