Power Line Communications (PLC) are commonly used in the indoor environment to set up a broadband network while using the existing electrical infrastructure. However, asymmetries in the electrical network are responsible for the conversion of the differential mode injected current into common mode current, which in turn generates undesired electromagnetic (EM) radiation. This paper presents a parametric study of the EM emissions due to indoor PLC, on the basis of Finite Difference Time Domain (FDTD) simulations and using a realistic coupler model. Results show the influence of the different parts of the electrical network and of the building structure on the radiated field.