An energy harvesting device is configured to surround a portion of an electrical cable (4), and includes a plurality of electrically separated and electrically conducting patch members (22, 22′, 24, 24′, 26, 26′) configured to be arranged in such a manner that an electric potential difference (V) is provided between a first outlet point (B) and a second outlet point (A). The patch members (22, 22′, 24, 24′, 26, 26′) are electrically connected to the first outlet point (B) and to the second outlet point (A). The patch members (22, 22′, 24, 24′, 26, 26′) are configured to be attached non-invasively direct onto the electrical cable (4).