Bussmann FRN-R Series Class RK...
IN STOCK (leaves warehouse same day if ordered before 3pm ET)
$17.71
Bussmann FRN-R Series Class RK5 Dual-Element Time-Delay Fuse

Bussmann FRN-R Series Class RK5 Dual-Element Time-Delay Fuse

(No reviews yet) Write a Review

Model: FRN-R-5

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

$17.71
Adding to cart… The item has been added
Free Shipping on orders over $199
We price match and offer bulk discounts! Click Add to Quote. It's quick and easy.
✨
Earn points with this purchase! You can redeem points for giftcards, iPads, XBox's and more. View Rewards
Free Keying on all locks
You may also like

Bussmann FRN-R Series Class RK5 Dual-Element Time-Delay Fuse

The Bussmann FRN-R Series is a Class RK5 dual-element time-delay fuse built for motor circuits, transformers, and other high-inrush electrical loads. Rated 250VAC/125VDC with a 200 kAIC interrupt rating at 250VAC, this series is available in amp ratings from 1A to 400A across the FRN-R family, giving electrical contractors and industrial facilities a single trusted platform for overcurrent protection across a wide range of circuit sizes. The blade end x blade end connection and non-indicating design fit standard fuse holders in panels, motor control centers, and distribution equipment.

Key Features

  • Dual-Element Design: combines time delay on overloads with fast clearing on short circuits for reliable motor circuit protection.
  • 10 Second Time Delay at 500%: rated current allows normal motor starting inrush and temporary overloads to pass without nuisance tripping.
  • Current Limiting Technology: reduces let-through energy and peak current to protect downstream equipment during fault conditions.
  • Class RK5 Classification: meets NEC requirements for motor circuit and transformer overcurrent protection.
  • 200 kAIC Interrupt Rating at 250VAC: delivers exceptional fault current clearing capability for industrial and commercial systems.
  • Voltage Rating: 250VAC/125VDC suits both AC and DC circuit protection applications.
  • Blade End Connection: blade end x blade end configuration for compatibility with standard fuse holders.
  • Amp Rating Range: FRN-R Series is offered from 1A to 400A, allowing the correct rating to be matched to motor full load current or transformer protection requirements.

Certifications & Compliance

  • CE Marked for international electrical safety compliance
  • Class RK5 rated to meet NEC motor and transformer circuit protection requirements

Technical Specifications

  • Voltage Rating: 250 Vac, 125 Vdc

Typical Applications

  • Motor Protection Circuits — HVAC, pump, compressor, and industrial machinery motors
  • Transformer Primary Protection for distribution and control transformers
  • Industrial Control Panels, Motor Control Centers, and Variable Frequency Drives
  • Commercial Lighting Circuits, including HID lighting and LED driver protection
  • Power Distribution Systems, Switchgear, and Electrical Service Panels
  • HVAC Equipment Protection for air handling units, chillers, and boilers

Why Bussmann?

Bussmann builds the FRN-R Series on rigorous testing, NEC compliance, and proven dual-element current limiting technology. The combination of time delay overload protection, fast short circuit clearing, and a 200 kAIC interrupt rating at 250VAC gives electrical professionals dependable, code-compliant overcurrent protection across the full 1A to 400A range, backed by decades of electrical protection innovation and industry-leading quality standards.

Manufacturer Resources

Product Specs

Class:
Class RK5
Fuse Indicator:
Non-indicating
Voltage Rating:
250VAC/125VDC
Compliances:
CE Marked
Number Of Elements:
Dual
Packaging Type:
Standard
Department:
Electrical
Product Type:
Fuse
Series:
FRN-R
Connection Type:
Blade End
Standards:
CE Marked
Product Group:
Fuses
Product Subgroup:
Other Fuses

Bussmann FRN-R-5 – Frequently Asked Questions

1) Will a Bussmann FRN-R fuse hold on motor starting inrush without nuisance blowing?
That is what the dual-element construction is for. The FRN-R is a dual-element time-delay fuse: one element rides through overloads long enough for a motor to start, the other clears short circuits fast. Bussmann rates it at 10 seconds of time delay at 500 percent of rated current, which covers normal locked-rotor inrush on HVAC compressors, pumps, and machinery motors. A non-time-delay fuse of the same amp rating would open on the same start.
2) What voltage circuits can the FRN-R fuse be used on?
250 volts AC or 125 volts DC, and that is a ceiling, not a target. The FRN-R will protect a 120V or 208V circuit fine, but it must never go on a 480V system. For 600V service you need the 600V Class RK5 companion, the Bussmann FRS-R, which is the same dual-element time-delay design at the higher voltage rating.
3) Can I put an FRN-R in a fuse block that currently has Class RK1 or Class H fuses?
Physically yes, with one direction of caution. Class RK5 shares the same dimensions and blade or ferrule mounting as Class RK1 and Class H/K of the same amp rating and 250V class, so an FRN-R drops into a standard R-class or H-class block. Going the other way is the problem: RK5 has a higher let-through energy than RK1, so if a panel schedule or an equipment label calls out Class RK1 for the short-circuit current rating of the assembly, substituting RK5 can void that SCCR. Match what the label specifies.
4) What amp ratings does the Bussmann FRN-R come in?
The FRN-R runs from 1A up to 600A, and the ladder is dense in the small sizes where motor full-load currents actually land: 1, 2, 5, 8, 9, 10, 12, 15, 20, 25, 30, 35, 40, 45, 50, 60, 70, 80, 90, 100, 110, 125, 150, 175, 200, 225, 250, 300, 350, 400, 450, 500, and 600 amps. Ordering is by amp rating appended to the series, so a 30 amp is FRN-R-30 and a 200 amp is FRN-R-200.
5) Do FRN-R fuses have blades or ferrule ends?
Blade end on both ends, per Bussmann's connection spec for the series. Blade construction is what the larger R-class ratings use, and it seats in standard R-rated fuse blocks and clips found in disconnects, motor control centers, and distribution panels. No adapter or special holder is required.
6) Is there a way to tell at a glance if an FRN-R fuse has blown?
No. The FRN-R is a non-indicating fuse, so there is no pop-up pin or window to read. Checking one means pulling it and testing continuity, or metering across the holder. If a maintenance crew needs visual blown-fuse identification on a panel, that has to come from an indicating fuse or a blown-fuse indicator light in the assembly, not from this series.
7) Can I use an FRN-R for transformer primary protection, not just motors?
Yes, and the time delay is the reason. Control and distribution transformers draw a heavy magnetizing inrush at energization, often many times full-load current for a few cycles. The dual-element time delay lets that pass while still protecting the primary against sustained overload and short circuit. Class RK5 is accepted under NEC rules for transformer and motor branch circuit overcurrent protection. The same behavior is why it suits HID lighting circuits and LED driver loads that inrush on switch-on.
8) Should I use a time-delay fuse or a fast-acting fuse on a motor circuit?
For any motor, transformer, or inrush load, time delay is the right choice, and that is what the FRN-R is. Fast-acting fuses are for resistive and electronic loads with no starting surge, where you want the quickest possible clearing. Put a fast-acting fuse on a motor sized to its full load current and it will blow on the first start; size it up to survive the start and it no longer protects the motor against a running overload. The dual-element design avoids that trade by handling the two conditions with two separate elements.
9) I need to replace a blown fuse marked FRN-R 60. What do I order?
FRN-R-60, the 60 amp member of the Bussmann FRN-R series. The number after the series designation is simply the amp rating, so any FRN-R marking on an old fuse translates directly to the part number. Replace it with the same amp rating rather than sizing up, since the existing rating was set to the motor nameplate or conductor ampacity. The whole series shares the 250VAC/125VDC rating and blade end construction, so nothing else about the holder changes.
10) Are Bussmann FRN-R fuses CE marked for a machine going to Europe?
Yes, the FRN-R carries the CE mark, so it can be listed on the compliance documentation for an OEM panel or machine build. Note the 250VAC rating when applying it there, since much of the European supply is 400/230V and the phase-to-phase voltage on those systems exceeds what this fuse is rated for.
How fast can I get the Bussmann FRN-R-5 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-5 come with a warranty?
Absolutely. The Bussmann FRN-R-5 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-5?
You can call, text, or email our expert support team for fast answers. We’re here to help with product selection, installation tips, and troubleshooting. Contact Us
Why buy the Bussmann FRN-R-5 from ZenSupply?
ZenSupply makes it easy to get the commercial door hardware you need—fast shipping, expert support, and rewards on every order. Our team is always ready to help you choose the right product for your project.
!