When choosing between a two and three prong power connector, one must know whether the device needs to be grounded or not. Grounded devices are considered Class I appliances. These appliances will often be framed in, or have open parts made out of a conductive material like metal that may come in contact with the internal circuitry. These exposed conductive parts represent a high risk of electric shock in instances of internal electrical failures. When an electrical failure happens, it is necessary to have a backup safety measure or “ground wire” to direct the flow of electricity back to the breaker and trip the circuit rather than risking electric shock to the user. Class II appliances are double insulated. In these appliances, no single internal electrical failure can cause an exposed, live wire, resulting in electric shock to the user. These devices will be encased in a non conductive material like PVC. An example of a class II appliance could be a power drill that has two prongs and is encased in plastic to protect the user from a short circuit. The easiest way to identify between a class I or class II appliance is to look for a double square symbol located somewhere on the casing or power supply. If no double square symbol is present, or the device plug has 3 prongs, it most likely falls under class I appliances.