Automated Lighting, 3rd Edition

Chapter 7

Overcurrent, Overvoltage, and Overtemperature Protection

It is an experience common to all men to find that, on any special occasion, such as the production of a magical effect for the first time in public, everything that can go wrong will go wrong. Whether we must attribute this to the malignity of matter or to the total depravity of inanimate things, whether the exciting cause is hurry, worry, or what not, the fact remains.—Nevil Maskelyne, magician (1863–1924)

Joseph Swan and Thomas Edison both recognized early in the development of electric lighting that things could go wrong, so both designed systems with a weak link to protect against short circuits and overloading. In 1881 Edison filed a patent for a “safety guard,” which ...