Hi. In theory it will jump between the protection section and the short circuit. For example, in a line between the main and secondary or sectional board. If there is a short circuit here will jump upstream or the protection of the main beam. If it were after the secondary board or, for example, inside a house would jump the secondary board or sectional. This is not always the case because many times because of the intensity of the short circuit jumps that of the main board and the interior does not. To avoid this, selectivity must be applied. This is to condition the protections depending on the section of the conductors. Generally speaking, in a home there has to be a thermal in the main board of 25 amps as the cable should be 4 mm². In a line of tapes 2.5 mm² cables are used, which corresponds to a thermal of 16 amperes, then there is selectivity for current in the thermals. regards