Bussmann Fusetron FRN-R Series...
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Bussmann Fusetron FRN-R Series Class RK5 Time-Delay Fuse

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Model: FRN-R-17-1/2

In Stock (leaves warehouse same day if ordered before 3pm ET)

$27.16
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Bussmann Fusetron FRN-R Series Class RK5 Time-Delay Fuse, 250V

The Bussmann Fusetron FRN-R series is a family of Class RK5 time-delay (TD) fuses rated for 250V circuits, engineered to deliver dependable overcurrent protection across a wide range of low- and mid-current electrical applications. This product page covers the FRN-R fuse family, available in amperage ratings from 1/4 Amp up to 17-1/2 Amp, giving electricians and facility teams a single, consistent Class RK5 time-delay platform to standardize on across control circuits, instrumentation, motor circuits, and branch-circuit protection points. Every fuse in the FRN-R family shares the same 250V voltage rating, Class RK5 construction, and dual-element Fusetron design, with the amperage rating selected to match the specific circuit being protected. The time-delay characteristic common to the entire series allows these fuses to ride through brief current surges, such as motor or transformer inrush, without unnecessary opening, while still providing fast response to genuine short-circuit and sustained overload conditions.

Key Features

  • Voltage Rating: 250V rating supports standard low-voltage circuit protection applications across the entire FRN-R family.
  • Fuse Class: Class RK5 construction for compatibility with RK5-rated fuse blocks, holders, and disconnect switches.
  • Time-Delay (TD) Design: Time-delay characteristic allows the fuse to ride through brief current surges, such as motor or transformer inrush, without unnecessary opening.
  • Amp Rating Range: Available from 1/4 Amp through 17-1/2 Amp, allowing a single family to cover both low-current control circuits and higher-current branch circuits.
  • Fusetron FRN-R Series: Part of the Bussmann Fusetron FRN-R fuse family, a recognized dual-element time-delay fuse line used across commercial and industrial electrical systems.
  • Dual-Element Construction: As a Fusetron-series fuse, each FRN-R fuse uses a dual-element design that separates overload sensing from short-circuit response for well-rounded circuit protection.
  • RK5 Rejection Fit: Class RK5 sizing allows the fuse to seat properly in RK5 rejection-style fuse blocks and holders, supporting correct fuse coordination.
  • Compact Fuse Format: Every rating in the FRN-R family fits standard Class RK5 fuse holders, simplifying fuse selection and stocking for maintenance teams standardized on the RK5 class.

Technical Specifications

  • Amperage Rating: 1/4A
  • Product Subgroup: Shop by Brand

Typical Applications

  • Control Circuit and Instrumentation Protection
  • Motor Starter and Control Transformer Circuits
  • Low-Current Branch Circuit Protection
  • Panelboard and Equipment Overcurrent Protection
  • Replacement Fuse for Class RK5 Fuse Holders and Reducers
  • Commercial and Industrial Electrical Maintenance

Why Bussmann?

Bussmann is a trusted name in circuit protection, and the Fusetron FRN-R series of Class RK5 time-delay fuses reflects that reputation with a shared 250V rating and time-delay performance designed for dependable, code-compliant operation across the full amperage range. For electricians and facility teams who need overcurrent protection that stands up to real-world motor and control-circuit demands, the Bussmann FRN-R family delivers consistent performance backed by Class RK5 construction and dual-element Fusetron design at every amp rating from 1/4 Amp to 17-1/2 Amp. With Bussmann fuses in place, facilities gain a recognized level of manufacturing quality and consistent fit within Class RK5-rated equipment, whatever amperage the circuit calls for. Choose Bussmann for electrical protection components built to keep circuits, equipment, and personnel safe.

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Manufacturer Resources

Product Specs

Product Type:
Time-Delay Fuse
Voltage Rating:
250V
Series:
Fusetron FRN-R
Standards:
Class RK5
Department:
Electrical
Product Subgroup:
Fuses
list_batch:
BUSS-20260919
Product Group:
Circuit Protection

Bussmann FRN-R-17-1/2 – Frequently Asked Questions

1) Will a Bussmann FRN-R fuse fit my existing RK5 rejection fuse block?
Yes. The Fusetron FRN-R is built to Class RK5 dimensions, so it seats in RK5 rejection-style blocks, holders and fused disconnects. That rejection sizing is the point of the class: it keeps a lower interrupting-rating fuse out of a holder specified for RK5. If your holder is Class R rejection prepped, the FRN-R drops in at any amp rating in the family.
2) Can I use a 250V FRN-R fuse on a 480V circuit?
No. Every FRN-R in the Fusetron family is rated 250V, so it is limited to circuits at or below 250 volts. For a 480V system you need the 600V Class RK5 equivalent, the Bussmann FRS-R, which is the same dual-element time-delay design at the higher voltage rating. Putting a 250V fuse on a 480V circuit is a safety problem, not a derating choice.
3) My fuse keeps blowing when the motor starts. Will a time-delay fuse like the FRN-R fix that?
That is exactly what the dual-element Fusetron design is for. The FRN-R rides through brief inrush from motor starting or transformer magnetizing current without opening, because overload sensing and short-circuit response are handled by separate elements. It still clears fast on a genuine short circuit or a sustained overload. If you are currently using a fast-acting (non-time-delay) fuse sized to the running load, swapping to the time-delay FRN-R at the correct rating is the normal fix for nuisance opening.
4) Is the FRN-R a Class RK1 fuse, and does it matter?
No, it is Class RK5. RK1 and RK5 share the same Class R rejection body dimensions, so an RK5 fuse physically fits an RK1 holder, but the two classes have different current-limiting performance. If an equipment nameplate or panel schedule calls specifically for Class RK1, use an RK1 fuse rather than substituting the FRN-R. Where the spec says RK5, or you are replacing an existing FRN-R, this is the right fuse.
5) What amp ratings does the Bussmann FRN-R come in?
The FRN-R ratings run from 1/4 Amp up through 17-1/2 Amp, including the fractional and half-amp sizes electricians need for control and instrumentation circuits. Order by the amp rating stamped on the fuse you are replacing: part numbers follow the pattern FRN-R-1/4 at the low end and FRN-R-17-1/2 at the top of the range.
6) Can I standardize all our control-circuit and motor fuses on one family?
That is the practical case for the FRN-R. Across the whole 1/4 to 17-1/2 Amp range the voltage rating (250V), the Class RK5 construction, and the dual-element time-delay characteristic are identical, so a maintenance crew stocks one family and changes only the amp rating. It covers control circuits, instrumentation, motor starter and control transformer circuits, and low-current branch circuit protection out of the same bin.
7) What is the difference between Bussmann FRN-R and the Low-Peak LPN-RK series?
Both are Class R, 250V, dual-element time-delay fuses that fit the same rejection holders. The Fusetron FRN-R is the Class RK5 version. Bussmann's Low-Peak LPN-RK is the Class RK1 version, which is more current-limiting and is what gets specified where equipment short-circuit current ratings depend on a Class RK1 fuse. For general motor, control and branch-circuit protection where RK5 is accepted, the FRN-R is the straightforward choice.
8) Will an FRN-R fit a fuse reducer in a larger disconnect?
Yes. The FRN-R family is listed for use as a replacement fuse in Class RK5 fuse holders and reducers, so if you have a reducer installed in an oversized switch to take a smaller Class R fuse, the matching FRN-R amp rating seats in it. Match the reducer's Class R size to the fuse you are ordering.
How fast can I get the Bussmann FRN-R-17-1/2 delivered?
Most orders ship the same day from our distribution partners, with quick delivery throughout the continental U.S. Need it urgently? Contact Us for expedited shipping options.
Can I return it if it doesn’t work for me?
Yes—ZenSupply offers a hassle-free return policy. If the product isn’t the right fit, reach out to our support team for a return authorization or setup a return by following our return instructions.
Does the Bussmann FRN-R-17-1/2 come with a warranty?
Absolutely. The Bussmann FRN-R-17-1/2 is backed by a manufacturer’s warranty. For full warranty terms, check the product documentation or Contact Us.
How do I get technical support or installation help for the Bussmann FRN-R-17-1/2?
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