This paper proposes a Lightweight version of the Precision Time Protocol, called L-PTP, for implementation on Powerline communication systems. The aim of this novel protocol is to reduce the number of messages exchanged to achieve synchronization, without penalizing its quality. L-PTP introduces several modifications to the original PTP and can be implemented on COTS devices. The paper focuses on the protocol and on the benefits of its combination with a virtual clock computation performed by a dynamic clock synchronization algorithm.