## 1 Introduction  
The Energy Information Administration (EIA) [1] has recently forecasted that world energy consumption will grow by 56% between 2010 and 2040. Although 80% of this energy is derived from traditional fossil fuels, renewable energy and nuclear power are the world's fastest-growing energy supplies--each with an increase of 2.5% per year. The increase in the number of different energy sources the current power grid has to accommodate and regulate leads to an unavoidable increase in the complexity of grid; despite that, this power grid still lacks an effective sensing and control platform that could help provide more intelligence to the management process. To alleviate this situation, cutting-edge sensing and control technologies are envisioned to be integrated into the current power grid. This integration will result in what is called the Smart Grid (SG), a more configurable, dynamic, reliable, flexible and effective power network. The Smart Grid can be observed as the evolution of the primitive state of the current electrical grids which in most cases consist of power transmission lines more than 50-60 years old [2] and whose conceptual design has remained unchanged for more than 100 years [3]. This out-of-date design, together with the lack of information collecting mechanisms, have been identified as the main triggers for serious power failures such as the European blackout on November 4, 2006 that affected more than 15 million European household) [4] and the North American black out in 2003, with an estimated cost of four to 10 billion dollars to the U.S. economy [5]. In light of this situation, it should be one of the priorities of every country's economy to provide their power grids with the required tools to enable intelligent asset management and successful health management. In this regard, successfully managing key power assets (substations, transformers and transmission towers among others) is considered to be as important as being able to predict their remaining useful life (RUL) or the time to the next failure. For such purposes, relevant data must flow in both directions: from power assets to central processing centers (sending acquired physical data such as temperature, voltage, vibrations, _etc._) and from there to power assets (making decisions such as for instance, triggering the ventilation system when the temperature increases in an indoor substation or balancing the incoming voltage) [6, 7]. Wireless Sensor Networks (WSNs) are considered to play an important role in this two-way communication process, which is in charge of bringing intelligence to the electrical network. This enabling technology has proven to have the ability to promote the use of automation, control and sensing techniques at a low cost and with very low-power consumption. Although other alternatives like wired communication systems could be considered as a more robust solution, they would require much more investment (very high deployment costs), an increase in maintenance costs and less network scalability, therefore leading to an inflexible communication solution for the new grid [8]--the network would not be able to accommodate to new requirements. The inherent decentralized nature of wireless systems, the decreasing evolution of prices, their easy and fast plug-and-play philosophy and a long-term durability have made WSN technology a clear winner in the field of power engineering [9]. The substantial benefit of a WSN lies in its capacity to deploy small battery-powered sensor nodes directly into critical power assets with practically no installation and maintenance work. These devices wirelessly send their processed sensed data to central nodes (also known as sink nodes) where data is converted into decisions and sent back to nodes.