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Fuse Blocks - An Introduction and Overview

Fuse Blocks and Fuse Types

Fuses are safety devices used to limit the amount of current through an individual circuit branch, or to limit the amount of current delivered from a voltage source such as batteries.  They will pass current below their rating under normal circumstances and open the circuit when the current rating is exceeded.  Limiter fuses are nearly always installed with a protective cover to prevent accidental shorts, shield adjacent components in case of catastrophic failure, and to protect users from electrical shock.  The US Coast Guard requires fuse holders installed on marine vessels have a protective cover in order to comply with law.

fuse block by riedonLimiter Fuses & ANL Type Fuses

Riedon supports two of the most common limiter fuses.  The “forklift” or ANL type fuses are widely utilized n low voltage branch circuits of 10 to 800 amps and remain the same physical size regardless of the current rating.  Although not mandatory, many of these fuses carry UL248-14 certifications.  Class T fuses are specially designed to react extremely fast, protect against a minimum of 200,000 amps without violent destruction, and carry UL248-15 certification.  They are available in two different sizes depending on the rated current.

Three Models of Fuses by Riedon

Riedon offers three models of limiter style fuse holders, all with covers and including an appropriately rated fuse as standard.  The NFB series is for use with forklift or ANL style fuses and features long studs for multiple wire terminations and a cover secured with acorn nuts to prevent accidental dislodging.  The FB1 and CFB1 fuse holders are for use with class T fuses from 110 to 200 amps, while the FB2 and CFB2 are for use with class T fuses from 250 to 400 amps.   Both variants feature a transparent and secure snap on cover and heavy-duty terminals to limit contact resistance and temperature rise.  The CFB series offers a unique bare-wire termination feature that accepts #6 – 250 MCM wire gauges

Fuse Blocks

When specifying a Riedon fuse block, begin by determining which fuse style will be required, class T or an ANL “forklift” fuse.  If an ANL fuse is needed then the model NFB and the necessary fuse rating are all that is needed to complete the part number.  If a class T fuse will be utilized, then it is necessary to decide on a termination type.  The selection can be further narrowed by knowing if the fuse rating will be 200 amps or less, or 250 amps or more, with the final step being to specify the fuse rating.  An example part number for a class T fuse holder with ring or spade terminals and an included fuse with a rating of 175 amps would be FB1-175.  To order the fuse without the holder, leave the current rating blank - FB1 specifies only the fuse holder without a fuse.

Class T Fuses

The most common application for class T fuses is for the protection of off-grid battery systems, often with PV or wind power to recharge them.  These may be installed in recreational vehicles, boats, or even remote cabins.  Although common for use in forklifts, the ANL style of fuses have been readily adopted for use as safety devices for the installation of high current accessories like strobe or spot lights, driving lights, winches, service radios, lift gates, and many other high current electrical accessories. 

To summarize, Riedon fuse holders provide a heavy-duty method of protecting high current DC circuits.  There are multiple mounting and fuse configurations to fill the needs of many installations.  Riedon fuse holders are very cost competitive in comparison to competitors that sell the fuses separately.  In addition, custom design requests are always welcome.