Connection device as per DIN EN 62561-1 for using the reinforcing bars (longitudinal bars) of reinforced concrete supports or walls as down conductors. By using a reinforcing bar contained in the reinforced concrete supports, the additional installation of round conductors (HDG steel) for lightning protection / earthing / equipotential bonding can be omitted. The electrically relevant connection is established across the entire length of the reinforced concrete support by a vertical reinforcing bar.