Smart Grid is one of the increasingly used critical infrastruc- ture that is essential for the functioning of a country. This coupled with Internet of Things (IoT) has huge potentials in several areas such as re- mote monitoring and managing of electricity distribution, traffic signs, traffic congestion, parking spaces, road warnings and even early detection of power influxes as a result of natural disasters, safety failures, equip- ment failures or carelessness. Despite the advantages of Smart Grids, there are security threats, privacy concerns and still open challenges re- lated to these issues in Smart Grids. This chapter seeks to provide a review of the security and privacy perspectives inherent in IoT enabled Smart Grids. Firstly the chapter explores the functionalities of Smart Grids as opposed to a traditional grid. Next the chapter provides an overview of Smart Grid architectures followed by positioning IoT con- cept into Smart Grid with a focus on architectures. Then, the proposed approach for identifying threats and attacks in IoT enabled Smart Grid, namely the security pyramid is presented. Lastly, we work on identifying the possible threats and attacks in the digital substation use case.