An electrode arrangement (1) for a nut welding assembly is provided comprising an electrode holder (5), a guide pin (7), a first electrode head, a purge air supply (11), and a control unit (13). The guide pin (7) is slidably arranged in an aperture (21) of the electrode holder (5) between an upper position and a lower position, where the electrode holder (5) comprises an internal space (23) to which the purge air supply (11) is connected. The guide pin (7) is arranged such that a connection (25) between the internal space (23) and the atmosphere (27) is open when the guide pin (7) is in the lower position and closed when the guide pin (7) is in the upper position. The control unit (13) is arranged to monitor an air pressure of the purge air supply (11) and to estimate a position of the guide pin (7) on the basis of the monitored air pressure. The present invention also relates to a nut welding assembly (3) comprising such electrode arrangement (1).
