Manual bypass systems are typically very reliable and can handle a wide range of conditions. In the event of an auto mains failure & manual bypass system can help you to maintain power to critical areas of your building. If you're like most people, you're probably familiar with the term "auto mains failure." This is when the electricity to a building or home is interrupted, usually due to a fault with the electric grid. In the event of an auto mains failure, the best course of action is usually to wait for the power to be restored by the grid. However, in some cases, it may be necessary to manually bypass the failed auto mains in order to maintain power to specific areas of the building.