In this paper we study the network impacts of power based distribution tariff which has been widely discussed in Finland as a future electricity distribution tariff also for small customers. The abundance of smart meters in Finland has enabled new forms of electricity pricing schemes, most notably hourly based energy pricing utilized by many Finnish retailers presently. However, the distribution pricing schemes are currently virtually same as during pre-deregulation and before the automatic meter reading (AMR) infrastructure. The paper presents the network impacts (voltage and current violations) of proposed tariff scheme based on load flow simulation of large-scale real-life distribution network from Finland. Simulations include the impact of both the retail and the distribution tariffs. Customers having large enough energy consumption (electric heating customers) are simulated to have a home automation for energy management. The results show that customer energy optimization can cause significant investment needs to the network and that power based distribution tariff can mitigate these issues.