Broadband Power Line Communication (PLC) technologies represent a main factor of the development of the digital convergence voice-data-video in the home environment. Such technologies use the power line network as a propagation and a communication medium whose quality depends mainly on the power grid topology, but also on the connected household electrical appliances which impedance and noise levels have a great impact on the PLC systems. In this paper, we propose a new approach for modeling temporal variations of noise and channel in indoor power line. Three-conductor power cable (phase, neutral and ground) is modeled by a RLCG circuit. RLCG parameters are deduced from the impedance measurement seen by the generator in open circuit and in short circuit. Cable model is validated in both time and frequency domains. Then, the temporal variation of periodic noise is investigated. The global model combining the channel model and the noise variations is validated by comparing simulated results with measurements.