History of the humble Automotive Blade Fuse

Although he may not have been the inventor of the fuse, the controversial inventor Thomas Edison filed one of the earliest fuse patents in 1890. Fuses (or circuit breakers) are now used in just about every man-made electrical circuit on the planet.

What is a Fuse?

A fuse consists of a metal strip or wire mounted between a pair of electrical terminals, usually enclosed by a non-combustible housing. Installed in series with the circuit on the upstream flow of electricity, the fuse assembly carries all of the charge passing through the protected circuit. Current flow causes the fuse's resistance to generate heat. The size and strength of the fusible part of the assembly is calculated so that the heat produced for a normal current is below the element's capacity. But, if the current gets too high, the element rises to a higher temperature, which causes the fuse strip or solder joint to melt, immediately interrupting the circuit.

Types of Fuses

Depending on their application and purpose, fuses are classified into many different types, including cylindrical fuses for applications that receive or distribute electricity, tube-type fuses used in residential electric appliances, surface-mount fuses for printed circuit boards and automotive fuses (our favourite type).

Exposed to extreme vibrations and a wide range of ambient temperatures, automotive fuses must work under demanding circumstances in harsh environments, while still being small, light and reliable. In the 1960s, most cars were fitted with glass tube fuses, early versions of which were handmade and not the most reliable. The big change came in the mid-1970s, when the American company, Littelfuse, patented its ATO® blade fuse.

About Littelfuse blade fuses

Formed by the American inventor and engineer, Edward V. Sundt, Littelfuse dates back to the 1920s, when Sundt sold his car to raise start up capital for fuse manufacturing. The US Patent Office refused Sundt's application for 'Little Fuse' as the words were too common, so he switched some letters around and formed Littelfuse Laboratories in 1927.

Having patented the first small but fast acting protective fuse - the type 1081-C - Sundt's first order (totalling $1.10 at the time) came from an ad placed in Radio News magazine, for some glass fuses to protect test meters. His first full year's earnings totalled $264 but the business soon took off. In ten years, turnover rose to over $100k - over $2M today. Thanks to the rapid growth of automobiles and aircraft and diversification into fuses for communications and other electronics, turnover exceeded $2m in 1943 ($33M today).

Despite the company's success in the 1940s, it would be another thirty years before the invention of the blade fuse. In 1968, with turnover exceeding $100M in today's money, Sundt retired and sold his company to the defense technologist, Tracor Inc., who took the company into the digital age, also developing fuses for the American space programme. In 2016, Littelfuse sales totalled more than $1 billion for the year.

Blade Fuse Advantages

Compared with glass tube fuses, blade fuses have a simpler structure and are lighter, more durable and more compact. They are handily colour coded to correspond with their amperage. The blade fuse subsequently evolved through a number of iterations but the standard blase fuse is still used in millions oof vehicles. We also use blade fuses in our plug-and-play replacement upgraded fuse replacement panels for classic Porsche 911 models.

Supplied with the industry standard Littelfuse ATO® blade fuses, all Classic Retrofit fuse panels feature an LED above each fuse, so there is no need to pull each fuse to find which one is blown: just look for the red LED. Hassle-free and especially easy when you're on the road, and also useful in troubleshooting electrical circuit issues: if the LED light is on and the fuse is OK, the break is somewhere else in the circuit.

Technology does not have to be big and shiny to impress. With a high breaking capacity, providing safety protection in low and medium voltage environments whilst also protecting from circuit overloads, those tiny little plastic fuses found under the bonnet in a Porsche 911 and many other classic cars can spell the difference between success and failure. When it comes to fuses, the blade fuse as used in our fuse panels is by far the best option. Do not skimp on using the best!