What is the difference between rk1 and rk5 fuses

How should I select the proper fuse amperage when I know the circuit amperage? Always follow NEC guidelines for applying low-voltage fuses. Time-delay fuses should be used for inductive loads and fast-acting fuses used to protect non-inductive loads. What is the difference between interrupting rating and the fuse's ampere rating? The interrupting rating is the maximum amount of energy the device can safely withstand.

The fuse's ampere rating is the amount of current that the fuse will allow through before beginning to operate. Both ratings are determined through testing. The interrupting rating is important because it is a safety rating. If a device with a low interrupting rating is used in circuit that has a higher available fault current the amount of energy that is potentially available if a fault were to occur , the device could potentially fail rupture or explode as it attempts to clear the fault, causing a safety hazard.

Are fuse reducers required for downsizing ampere ratings of Class L fuses? No, fuse reducers are not required or available. The bolt hole patterns of Class L fuses are designed to allow you use smaller ampere ratings.

Yes, fuseholders do require derating. Often times derating for a fuseholder is overlooked by an engineer because it does not specified on the datasheet. Please review the attached document for derating of fuseholders. No - No fuse manufacturer offers Class L fuse blocks. Class L fuses are bolted directly on buss bars or used with bolted-pressure contact switches.

A rejection feature is used to prevent fuses with a lower voltage or interrupting rating such as Class H and Midget fuses from being used in a circuit that needs a higher rating. Class R and CC fuseblocks incorporate a built-in rejection feature while Class J and T blocks reject based on physical size. How can I find out which fuse block or holder I can use with any of your fuse series? The attached file is a cross reference of the appropriate fuseholder or fuse block that can be used with any Littelfuse brand fuse series.

Does Littelfuse have any legal disclaimers or notices about information on www. Please read these disclaimers and notices carefully:. This web site is owned by and under the control of Littelfuse, Inc. Access to and use of this web site and all of Littelfuse's content, services, materials, information, databases and systems are subject to these Disclaimers and Notices, any Agreements and applicable laws and regulations including all export and import laws, regulations and restrictions , all of which are subject to change and revision from time to time without prior notice.

From time to time, Littelfuse may a supplement or make changes to these Disclaimers and Notices and other rules or access and use procedures, documentation, security procedures and standards for equipment, b change the type and location of Littelfuse's system equipment, facilities or software, or c modify or withdraw any particular service or product referred to in this web site or any Littelfuse database, material, service or system.

Littelfuse reserves the right to terminate access to this web site or take other actions it reasonably believes necessary to comply with the law or to protect its rights or customers.

Any access or attempt to access or use this web site for any unauthorized or illegal purpose is strictly prohibited. This web site is provided without charge as a convenience to users to be used for the purposes of information, education and communication.

While Littelfuse's information and advice contained in this web site have been prepared and compiled from sources believed to be reliable, Littelfuse makes no guarantee as to, and assumes no responsibility for, the correctness, sufficiency or completeness of such information, material or recommendations. Littelfuse does not represent or endorse the accuracy or reliability of any of the information, content or advertisements contained on, distributed through, or linked, downloaded or accessed from this web site, nor the quality of any products, information or other materials or services displayed, obtained or purchased by you as a result of your use of this web site or any Littelfuse service, database, materials or system.

You hereby acknowledge that any reliance upon any information or materials shall be at your sole risk. Littelfuse reserves the right, in its sole discretion and without any obligation, to correct any error or omissions in any portion of this web site or any Littelfuse service, database, materials or system at any time, with or without notice to you. Without Littelfuse's prior written consent, which consent may be given or withheld in Littelfuse's sole discretion, you may not: a resell, sublicense, rent, lease or otherwise publicly distribute any Littelfuse information, services or database, or any part or parts thereof or information contained therein, or any access thereto; b use your access to this web site or Littelfuse's information, services, database or system to export or re-export technical data in violation of U.

Any information, including but not limited to remarks, suggestions, ideas, graphics or other submissions, communicated to Littelfuse through this web site is deemed non-confidential and is the exclusive property of Littelfuse.

Littelfuse is entitled to use any information or ideas submitted for any purpose without restriction and without compensation or acknowledgement of its source. Except as otherwise identified, the trademarks including names, logos, slogans and service marks appearing at this web site, whether registered or unregistered, are the property of Littelfuse or Littelfuse's affiliates. Such marks are not to be copied, reproduced, published or in any way used without the written permission of Littelfuse or the identified owner of the trademark.

Except as otherwise identified, the copyright in the content of this web site is owned by Littelfuse. No part of this web site may be published, stored or transmitted in any form or means without the express written permission of Littelfuse.

You may download content displayed on this web site for non-commercial, personal use only and must retain all copyright and other proprietary notices contained in the content. No person may establish Hyperlinks either to this web site or away from this web site without the prior written consent of an appropriate Littelfuse officer, which consent may be given or withheld in Littelfuse's sole discretion.

In its sole discretion, Littelfuse reserves the right to remove a Hyperlink to this web site or away from this web site at any time and for any reason. Contact Littelfuse at legal littelfuse. All Hyperlinks approved shall be to the home page of this web site.

Framing at this web site is expressly prohibited. Littelfuse advises you to exercise discretion while browsing this web site and the Internet.

In addition, Hyperlinks on this web site may direct you to sites containing information that some people may find offensive or inappropriate. Such linked web sites may not be under the control of Littelfuse and Littelfuse does not make any representations concerning any such web sites which you may access via a Hyperlink from this web site, and accordingly Littelfuse is not responsible for the accuracy, copyright compliance, legality, legitimacy or decency of material contained in web sites which may be accessible via a Hyperlink to or from this web site or for the Hyperlink itself.

Littelfuse is providing these Hyperlinks to you only as a convenience and the inclusion of any Hyperlink on this web site is not and should not imply any endorsement by Littelfuse of such linked web sites. If any part or parts of these Disclaimers and Notices are held to be invalid, the remaining parts will continue to be valid and enforceable.

Nothing in these Disclaimers and Notices affects any statutory rights of consumers that cannot be waived or limited by contract. The use by you of this web site, the Littelfuse information, content, services or other materials, and any and all other matters between Littelfuse and you related hereto, shall be governed by applicable United States federal law and the laws of the State of Illinois, excluding its conflict-of-laws rules.

You hereby agree to waive any right to a jury trial in any suit arising out of or relating to this web site or any Littelfuse information, content, service or other product. Any suit or proceeding arising out of or relating hereto must be commenced within one year from the date the right, claim, demand or cause of action being asserted first came into being. Venue for all disputes arising out of or relating to this Agreement shall be in the state and federal courts situated in Chicago, Illinois.

You agree to comply with all applicable export laws, regulations and restrictions. Information Littelfuse places on or makes available through this web site may contain references or cross references to Littelfuse or third party products, programs and services that are not announced or available in your country. Such references do not imply that either Littelfuse or such third party intends to announce or make available such products, programs or services in your country. Consult Littelfuse or the applicable third party for information regarding any such products, programs or services.

This web site may contain other proprietary notices and copyright information, the terms of which must be observed and followed. Any rights not expressly granted herein are reserved. Government" , is provided with Restricted Rights. Use, duplication or disclosure by the U. If the user has any questions regarding this web site or its contents, or these Disclaimers and Notices, contact Littelfuse at legal littelfuse.

Can a time delay fuse be used to replace a fast acting fuse? Fast-acting fuses are generally used to protect sensitive components from damage so replacing fast-acting fuses with a time-delay fuse could result in damage to your equipment.

NEC guidelines are also different for applying fast-acting and time delay fuses. Fuse sizing may vary. It is best to thoroughly understand the circuit before making a decision to switch from a fast-acting fuse to one with time delay. The attached datasheet explains the color coding system. Do you have an explanation for your part number nomenclature? Littelfuse Part Number Explanation.

Customers call for a 3AG size solution and we have nothing to offer. For customers requiring a 3AG solution Littelfuse does not offer a fuseholder to fit your needs. Electrically, the series In-Line fuseholder can handle the voltage but they are all rated at 32 Volts because of the risk of shock to the user when the holder is opened.

RK1 fuses can provide better protection because they allow less damaging energy to pass through them while opening blowing. These non-renewable fuses are current-limiting and intended for the protection of components sensitive to short-time overloads, non-inductive loads, and short-circuit protection of motor circuits.

Class CC fuses are available with DC ratings. The interrupting rating is kA rms symmetrical. Class G fuses. These fuses were specifically created for use in lighting and appliance panel boards that are equipped with a special fusible-switch unit.

These are non-renewable cartridge fuses that are for use only in AC circuits where interrupting ratings to kA rms symmetrical are required. These can also be available with DC ratings. The innovative design of this class of fuse was selected so as to prevent the interchangeability with any other fuse class.

Class G fuses are current-limiting and are able to be so labeled per UL , which prescribes the maximum peak let-through and I2t let-through values permitted for this class of fuse. The time delay test feature is optional. Class H fuses. This is a cartridge fuse and is intended for general purpose branch circuit, lighting circuit, and the protection of non-inductive equipment like electric ovens and resistance heaters.

You can select from renewable and non-renewable Class H fuses. The renewable fuses allow the user to replace the internal fusible link after the fuse operates. All Class H units are tested for short-circuit requirements and are available with DC ratings. The short-circuit power factors are relatively high: 0. The actual short-circuit power factors encountered in typical installations are on the order of the above test values, when the available short-circuit current is 10kA rms symmetrical or less.

With respect to the time delay feature of fuses, the renewable types cannot perform the time delay but the non-renewable can. Class H fuses, both non-renewable and renewable, are often misapplied in the electrical industry for a couple reasons. First, their minimal 10kA interrupting rating is easy to exceed in an industrial plant or commercial building.

Second, workers unfamiliar with the differences between devices might be tempted to install more than one link in a renewable fuse. Class J fuses.

These non-renewable fuses are current-limiting and conform to Class J fuses are available with DC ratings. Power fuse safety and test procedures have been established by the U. S, Europe and Asia as performance standards. Power fuses standards of low-voltage volts or less have evolved into distinct classes. Not only when you first specify them, but also when you replace them. To aid in selection, manufacturers produce fuses designated by class.

Many are dual rated and can be used in dc applications. All are current limiting and carry a kA interrupting rating. Some are self-certified up to kA IR. Most RK fuses are time-delay dual element design. Fast acting RK fuses are also available for sensitive or critical component protection applications. Class RK fuses are commonly used in mains, feeder and branch circuits, motors, transformers, solenoids and general purpose circuits.

This means Class RK1 allow less damaging energy to pass through them while opening blowing. Recommended applications for RK1 fuses are the same as RK5 in most cases and as mentioned above, they offer greater current limitation.