Recently, the multi phase transmission systems are being considered as a viable transmission alternative to achieve efficient utilization of rights of way and increased transmission capability to meet growing power supply demands. However, detailed modelling and analysis of multi phase systems and associated transformers have not been carried out to substantiate the preliminary findinge. This paper is an attempt in this direction by presenting the various representations of multi phase components; transmission lines, transformers and loads suitable for balanced as well as unbalanced network analysis. Employing one of the proposed modelling schemes, the impact of addition of multi phase lines in existing three phase network is investigated for the load flow analysis. The results of a sample system are presented and discussed.