Fuse where to buy

By , Underwriters Laboratories had established size and rating specifications to meet safety standards. The renewable type fuses and automotive fuses appeared in , and in Littelfuse started making very low amperage fuses for the budding electronics industry. Other non-glass fuse sizes and constructions were determined by functional requirements, but they still retained the length or diameter dimensions of the glass fuses. Their designation was modified to AB in place of AG, indicating that the outer tube was constructed from Bakelite, fibre, ceramic, or a similar material other than glass.

An important part of developing quality overcurrent protection is an understanding of system needs and overcurrent protective device fundamentals. This section discusses these topics with special attention to the application of fuses. All electrical systems eventually experience overcurrents. Unless removed in time, even moderate overcurrents quickly overheat system components, damaging insulation, conductors, and equipment. Large overcurrents may melt conductors and vaporize insulation.

Very high currents produce magnetic forces that bend and twist bus bars. These high currents can pull cables from their terminals and crack insulators and spacers. Too frequently, fires, explosions, poisonous fumes and panic accompany uncontrolled overcurrents. This not only damages electrical systems and equipment, but may cause injury or death to personnel nearby.

Industry and governmental organizations have developed performance standards for overcurrent devices and testing procedures that show compliance with the standards and with the NEC. Electrical systems must meet applicable code requirements including those for overcurrent protection before electric utilities are allowed to provide electric power to a facility.

An overcurrent is any current that exceeds the ampere rating of conductors, equipment, or devices under conditions of use. The term "overcurrent" includes both overloads and short-circuits. An overload is an overcurrent confined to normal current paths in which there is no insulation breakdown. Sustained overloads are commonly caused by installing excessive equipment such as additional lighting fixtures or too many motors.

Sustained overloads are also caused by overloading mechanical equipment and by equipment breakdown such as failed bearings. If not disconnected within established time limits, sustained overloads eventually overheat circuit components causing thermal damage to insulation and other system components.

Overcurrent protective devices must disconnect circuits and equipment experiencing continuous or sustained overloads before overheating occurs. Temporary overloads occur frequently.

Common causes include temporary equipment overloads such as a machine tool taking too deep of a cut, or simply the starting of an inductive load such as a motor.

Since temporary overloads are by definition harmless, overcurrent protective devices should not open or clear the circuit. It is important to realize that fuses selected must have sufficient time-delay to allow motors to start and temporary overloads to subside. However, should the overcurrent continue, fuses must then open before system components are damaged. A short-circuit is an overcurrent flowing outside of its normal path.

Types of short-circuits are generally divided into three categories: bolted faults, arcing faults, and ground faults. Each type of short-circuit is defined in the Terms and Definitions section. A short-circuit is caused by an insulation breakdown or faulty connection. During a circuit's normal operation, the connected load determines current. Since there is no load impedance, the only factor limiting current flow is the total distribution system's impedance from the utility's generators to the point of fault.

A typical electrical system might have a normal load impedance of 10 ohms. But in a single-phase situation, the same system might have a load impedance of 0.

If the same circuit has a 0. As stated, short-circuits are currents that flow outside of their normal path. Regardless of the magnitude of overcurrent, the excessive current must be removed quickly. If not removed promptly, the large currents associated with short-circuits may have three profound effects on an electrical system: heating, magnetic stress, and arcing. Heating occurs in every part of an electrical system when current passes through the system.

When overcurrents are large enough, heating is practically instantaneous. The energy in such overcurrents is measured in ampere-squared seconds I2t. An overcurrent of 10, amperes that lasts for 0.

If the current could be reduced from 10, amperes to 1, amperes for the same period of time, the corresponding I2t would be reduced to 10, A2s, or just one percent of the original value. If the current in a conductor increases 10 times, the I2t increases times.

A current of only 7, amperes can melt a 8 AWG copper wire in 0. Within eight milliseconds 0. Any currents larger than this may immediately vaporize organic insulations. Arcs at the point of fault or from mechanical switching such as automatic transfer switches or circuit breakers may ignite the vapors causing violent explosions and electrical flash. Magnetic stress or force is a function of the peak current squared.

Fault currents of , amperes can exert forces of more than 7, lb. Stresses of this magnitude may damage insulation, pull conductors from terminals, and stress equipment terminals sufficiently such that significant damage occurs.

Arcing at the point of fault melts and vaporizes all of the conductors and components involved in the fault. Additional short-circuits are often created when vaporized material is deposited on insulators and other surfaces.

Sustained arcing-faults vaporize organic insulation, and the vapors may explode or burn. Since overcurrent protection is crucial to reliable electrical system operation and safety, overcurrent device selection and application should be carefully considered. When selecting fuses, the following parameters or considerations need to be evaluated:.

The Class L fuses are the only time-delay fuse series available in these higher ampere ratings. To select the proper overcurrent protective device for an electrical system, circuit and system designers should ask themselves the following questions before a system is designed:.

Answers to these questions and other criteria will help to determine the type overcurrent protection device to use for optimum safety, reliability and performance. Littelfuse, Inc. We use cookies to collect information about how you interact with our website and to remember you. We use this information to improve and customize your browsing experience and for analytics about our visitors on this website and other media.

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Products Automotive Sensors Automotive Sensors Littelfuse Automotive Sensor Products offer a wide range of sensors for use in monitoring various vehicular functions in the areas of passenger safety, comfort and convenience plus vehicle powertrain, chassis and emission applications.

Chassis Comfort and Convenience. Emissions Passenger Safety. Powertrain xEV Sensors. Littelfuse battery management devices provide methods of conserving battery power, protecting against over-discharge, combining and protecting auxiliary equipment such as liftgate motors. Littelfuse battery mini-Breakers provide battery cell protection for high-capacity Lithium Polymer and prismatic cells. Metal Hybrid Protection. Electrical sockets, plugs and coils used for connection of a truck and trailer on commercial vehicles or caravans for 12 and 24V systems.

Connector Accessories Greycon Connectors. Common Mode Noise Filters CMF attenuate common mode noise in differential and balanced transmission, and power supply and audio lines. Littelfuse offers a comprehensive line of fuse blocks, fuse holders, and fuse accessories for automotive, electronic, and electrical markets. Fusible Switches and Panels Fusible Switches and Panels Provide a complete, one-piece solution for easy procurement and code compliance.

Dissipate high voltage transients through a contained plasma gas with high surge capability, low capacitance and small size. Magnetic sensing products utilizing Reed and Hall Effect technologies, with custom solutions available. Low capacitance polymer base product for protecting high speed data circuit from ESD damage and maintaining data integrity.

Polymer-enhanced, precision Zener diodes that offer resettable protection against multi-Watt fault events without the need for multi-Watt heat sinks. Power Semiconductors Power Semiconductors High reliability power semiconductors utilize the latest technology. Stacks, Subsystems, and Assemblies Bare Die. TD and Chip Telecom. Our surge protection devices SPDs and modules are designed to provide protection from transient overvoltage.

They are thermally-protected and built with high-quality, dependable materials. Features manually-operated, foot-operated, and mechanically-operated switches; and switches operated by temperature or pressure. Orders on stock items received by GMT are sent out by recorded First Class post at the close of business most first class mail arrives next day though we cannot guarantee this , or for a small additional charge we can arrange guaranteed delivery by courier.

Rep of Ireland. If you are based outside the UK, Europe or America, please contact us anyway - in most cases we can arrange shipping at reasonable rates. To find the fuse you require browse the categories to the left - if you know the name or product code of your fuse you can also use the Search facility to go straight to your item.

You may also find our conversion chart useful for finding equivalent fuses from different manufacturers. Remember - if you can't immediately find what you need through this website simply call our highly trained sales staff who will be able to quickly locate the fuse you need and complete your order by telephone. Quick Find.