Fuses are an important protective device for electrical components. Fuses work by blowing out, or melting, and interrupting electrical current when the circuit becomes overloaded for a specific amount of time. The overload tolerance varies depending on the application and the fuse, because some applications, such as vehicle components, experience frequent, temporary overloads. Other applications can potentially become damaged beyond repair as the result of a brief over-current.

Fuse specifications include voltage rating, interrupt rating, current rating and rated braking capacity. These specifications indicate the conditions at which a fuse will blow. Fuses are mounted in a couple of ways. They can be mounted on a surface by soldering or temporary clipping. Fuses are also made from a variety of materials, and hazardous materials typically should be avoided. Fuses made from non-hazardous materials are labeled with "RoHS compliant." When buying fuses, consider the following:

1. Buy time-delay fuses if your application experiences temporary over-currents.

2. Use fast-acting fuses with applications that can't tolerate any kind of extended overload.

3. Purchase automotive fuses when installing fuses in vehicles.

Action Steps
The best contacts and resources to help you get it done

Buy a fuse with a time delay

Time-delay fuses are used in applications where brief overloads occasionally occur without damaging the equipment. Time-delay fuses are also called 'slow-blow fuses' and generally take longer than 10 seconds to blow out. With continuous overload, the fuse heats up and melts solder contained within the fuse, which then releases a spring causing the blowout.

I recommend: Find time-delay fuses at Industrial Equipment Recovery. The fuse distributor keeps several manufacturers' products in stock. Buy fuses online from Automation Direct. The company has a large inventory of industrial fuses, including time-delay fuses.

Purchase an industrial fuse that's fast acting

Fast-acting fuses are necessary when even a momentary overload would be detrimental to the application's electrical circuit. Fast-acting fuses vary in how quickly they blow out, and some manufacturers offer models called 'very fast-acting' fuses. A properly functioning fast-acting fuse will blow before an over-current can cause damage.

I recommend: Purchase fast-acting, surface-mount fuses from Bel Fuse. The manufacturer's fast-acting fuses have received the approval of several safety agencies and are compliant with the Restriction of Hazardous Substances Directive. Browse a large inventory of fuses, many of which are fast acting, at online distributor Tedss.com.

Order automotive fuses

Automotive fuses are designed to function under the unique conditions within a vehicle. Automotive fuses are designed to blow out with a continuous overload, as vehicles often experience momentary overloads, such as when the motor starts.

I recommend: Littelfuse designs and manufacturers fuses for many industries, including automotive. The company offers an environmentally friendly line of lead-free, RoHS-compliant fuses. Steven Engineering offers electric fuses manufactured specifically for automotive and aircraft applications. Find specialty forklift truck fuses at Fastenal. Fuses are available in voltages ranging from 32 to 130 Vdc, current ratings ranging from 1 to 800 amps and lengths ranging from 2.810 to 4.710 inches.

Use a general-purpose electric fuse

Many electric fuses have versatile uses. When purchasing a general-purpose electric fuse, check the fuse's specifications to make sure it's compatible with the application and will blow out before an over-current can cause damage.

I recommend: Purchase fuses from Ferraz Shawmut. The fuse manufacturer offers a line of current-limiting, general-purpose fuses. Find the products of several fuse companies at Monster Fuses. The distributor tests every fuse before shipment and labels the fuse with the test result.

Tips & Tactics

Helpful advice for making the most of this Guide

• •  When checking fuse prices, look for discounts when buying in bulk. Fuse blowouts are commonplace and you'll need to keep a stock of fuses to prevent equipment downtime.