Fuses are designed to operate when over-currents, large and small, occur within electrical equipment; they thus interrupt the flow of current, preventing damage. They are needed for various power electric systems, for stationary and automotive applications, as well as power grid components like PV systems and distribution lines. Different types of equipment and voltages require special fuses, and their behaviour must be understood to guarantee correct choice and safe operation. For the 3rd edition in 2004, Wright and Newbery's classic had been revised to include pre-arcing and arcing behaviour, retrofitting of fuses, chip and automotive fuses, and insulated gate bipolar transistor (IGBT) protection. Edition 4 includes updates on standards and new applications. Data, standards descriptions and many illustrations have been revised and updated. Chapters cover pre-arcing and arcing behaviour of cartridge fuselinks, constructions and types of low-and high-voltage fuses as well as miniature, plug and other small fuses, various applications, standards, manufacture, quality assurance and inspection. This reference is indispensable for researchers involved with power electric equipment, grids and motors, and experts engaged in fuse development, design and production.