After the deregulation of the German electricity markets, network access charges are based on contractual arrangements between energy producers and industrial consumers. As the electricity networks are incontestable natural monopolies, the operators are able to set (monopolistic) charges at their own discretion, restricted only by possible cartel office interferences. Estimations show a relation between network access charges and operator's economic independence as well as level of vertical integration: on the low voltage level for an annual consumption of 1700 kW/h, vertically integrated firms set significantly lower access charges than vertically separated suppliers, whereas incorporated network operators charge significantly higher charges.