Fencing system for protecting a site of a given perimeter against intrusion, comprising: • an electric generator, • a first bar capable of being arranged along the perimeter in an at least partially vertical direction, • a first upper guide which is mechanically coupled to the first bar, • a first lower guide which is mechanically coupled to the first bar and offset from the first upper guide along the first bar, • a second bar capable of being arranged along the perimeter in an at least partially vertical direction and spaced from the first bar along the perimeter, • a second upper guide which is mechanically coupled to the second bar, • a second lower guide which is mechanically coupled to the second bar and offset from the second upper guide along the second bar, • a first section of electric fence wire which is electrically connected to the electric generator and arranged so as to be guided by the first upper guide and the second upper guide, • a second section of electric fence wire which is arranged so as to be guided by the first lower guide and the second lower guide, characterised in that • the first and the second bar are made of an electrically insulating material, • the system is arranged such that the second section is at an electrical potential which is different from that of the first section, • the first upper guide is arranged in a first direction relative to the first bar, • the first lower guide is arranged in a second direction relative to the first bar, the second direction being substantially opposite the first direction, • the second upper guide is arranged in the second direction relative to the second bar, • the second lower guide is arranged in the first direction relative to the second bar, and • it further comprises a detection device arranged to detect an electrical contact between the first section and the second section, wherein the guides (21, 22, 31, 32) are made of an electrically conductive material, the system further comprising a conductive element in electrical contact with the first lower guide and extending along the first bar from the first lower guide to the first upper guide without being in electrical contact with the first upper guide, and a conductive element which is in electrical contact with the second lower guide and extending along the second bar from the second lower guide to the second upper guide without being in electrical contact with the second upper guide, each conductive element (41, 42) comprising a plurality of rings surrounding the respective bar (11, 12). • an electric generator, • a first bar capable of being arranged along the perimeter in an at least partially vertical direction, • a first upper guide which is mechanically coupled to the first bar, • a first lower guide which is mechanically coupled to the first bar and offset from the first upper guide along the first bar, • a second bar capable of being arranged along the perimeter in an at least partially vertical direction and spaced from the first bar along the perimeter, • a second upper guide which is mechanically coupled to the second bar, • a second lower guide which is mechanically coupled to the second bar and offset from the second upper guide along the second bar, • a first section of electric fence wire which is electrically connected to the electric generator and arranged so as to be guided by the first upper guide and the second upper guide, • a second section of electric fence wire which is arranged so as to be guided by the first lower guide and the second lower guide, characterised in that • the first and the second bar are made of an electrically insulating material, • the system is arranged such that the second section is at an electrical potential which is different from that of the first section, • the first upper guide is arranged in a first direction relative to the first bar, • the first lower guide is arranged in a second direction relative to the first bar, the second direction being substantially opposite the first direction, • the second upper guide is arranged in the second direction relative to the second bar, • the second lower guide is arranged in the first direction relative to the second bar, and • it further comprises a detection device arranged to detect an electrical contact between the first section and the second section,