Mersen A2K20R Class RK1 Fast-Acting Fuse, 20A 250VAC/250VDC
The Mersen A2K20R is a Class RK1 Fast-Acting Amp-Trap fuse rated 20A at 250VAC/250VDC, built for reliable overcurrent protection in demanding electrical systems. This professional-grade fuse features ferrule terminals in tin-plated copper and a GMG body insulating material, with a 2-inch overall length designed for clip mounting. Backed by a 200 kA breaking capacity and RoHS compliant construction, it delivers fast-acting response and superior current-limiting performance for both AC and DC circuit applications.
Key Features
- Ampere Rating: 20A rating provides precise overcurrent protection for medium-load circuits with reliable trip characteristics.
- Class RK1 Design: Delivers superior current-limiting performance and enhanced safety under fault conditions.
- Fast-Acting Speed Characteristic: Ensures immediate response to overcurrent conditions for optimal circuit and equipment protection.
- 250VAC/250VDC Dual Rating: Versatile voltage compatibility supports both AC and DC applications, rated at 50/60 Hz.
- 200 kA Breaking Capacity: Exceptional fault current interruption capability for high-demand industrial and commercial installations.
- Ferrule Terminal Construction: Tin-plated copper terminals provide secure connections and excellent conductivity with corrosion resistance.
- GMG Body Insulating Material: Durable body construction supports dependable performance in demanding electrical environments.
- Compact Clip-Mount Design: 2-inch product length with clip mounting method for straightforward installation.
Certifications & Compliance
- RoHS Compliant
Technical Specifications
- Body Insulating Material: GMG
- Rohs Compliant: Yes
Typical Applications
- Industrial Control Panels and Motor Control Centers
- Commercial HVAC and Lighting Systems
- Power Distribution Equipment and Switchgear
- Process Control and Automation Systems
- Renewable Energy and Battery Storage Systems
- Emergency Power and UPS Applications
Why Mersen?
Mersen Class RK1 fuses deliver proven reliability with RoHS compliant construction and professional-grade materials, including GMG body insulation and tin-plated copper ferrule terminals. The 200 kA breaking capacity and fast-acting response of the A2K20R provide superior, code-compliant overcurrent protection for critical electrical systems in industrial and commercial installations.
Manufacturer Resources
Mersen Product Catalog
Product Specs
- Product Type:
- Fast-Acting Fuse
- Amperage Rating:
- 20A
- Voltage Rating:
- 250VAC/250VDC
- Grade:
- Class RK1
- Product Finish:
- Tin-Plated Copper
- Product Material:
- GMG
- Standards:
- RoHS Compliant
- Department:
- Electrical
- Product Group:
- Circuit Protection
- Product Subgroup:
- Fuses
- Product Length:
- 2 in
- Product Weight:
- 0.038 lb
Mersen A2K20R – Frequently Asked Questions
1) Will a Mersen A2K20R fit a standard Class R fuse block, and can I use it on a 480V circuit?
The A2K20R is a Class RK1 ferrule fuse with a 2 inch overall length that clips into a Class R block sized for 250V, 20A ferrule fuses. Voltage is where people get caught: it is rated 250VAC/250VDC only, so it cannot be used on a 480V system. For a 480V panel you need a 600V class fuse instead.
2) Can I use the A2K20R on a DC circuit like a battery bank or solar array?
Yes. The A2K20R carries a 250VDC rating alongside its 250VAC rating, so it can protect DC circuits up to 250V, including battery storage and renewable energy applications. Many fuses of this size are AC-only, so the dual rating is the reason to pick this one for DC work.
3) Is a fast-acting RK1 fuse the right choice for a motor circuit, or do I need time-delay?
The A2K20R is fast-acting, which means it responds immediately to overcurrent. That suits transformer secondaries, control circuits, switchgear and non-motor loads, but a motor's inrush will usually blow a fast-acting fuse on startup. For motor branch circuits you want a time-delay fuse, such as the Littelfuse CCMR Series Class CC time-delay fuse (CCMR040 is the 40A version). Match the class to your fuse block: RK1 and Class CC are not interchangeable in the holder.
4) Can an RK1 fuse replace an RK5 fuse of the same amp rating?
RK1 and RK5 share the same Class R dimensions and rejection feature, so a 250V 20A RK1 like the A2K20R drops into the same block as a 250V 20A RK5. RK1 is the more current-limiting of the two, so it lets through less energy on a fault. Going the other way, RK5 in place of RK1, can undercut the equipment's short circuit rating, so check the panel label before substituting down.
5) Is a Littelfuse AGU or AGA glass tube fuse an equivalent to the Mersen A2K20R?
No. The Littelfuse AGA5 is a 5A glass fuse in the AGA series and the AGU is an AG-series glass tube fuse, both small glass-body automotive and electronics style cartridges. The Mersen A2K20R is a Class RK1 branch-circuit fuse with a GMG body, tin-plated copper ferrules and a 200 kA breaking capacity at 250VAC/250VDC. Glass tube fuses do not carry the interrupting rating or the class listing required where an RK1 is specified, so they are not a substitute in a control panel or distribution application.
6) What is the difference between the Mersen A2K20R and a Littelfuse CCMR Class CC fuse?
They differ in both fuse class and speed characteristic. The Mersen A2K20R is a Class RK1 fast-acting fuse rated 20A at 250VAC/250VDC, so it clears overcurrents without an intentional delay. The Littelfuse CCMR040 is a Class CC time-delay fuse rated 40A, which is built to ride through motor inrush. Class CC and Class RK1 use different rejection features and mounting hardware, so choose based on what the fuse block in the panel is prepped to accept and on whether the load needs a delay.
7) What interrupting rating does the Mersen A2K20R have for a high fault current panel?
200 kA interrupting (breaking) capacity, which covers service entrance and industrial switchgear locations where available fault current is high. That rating combined with the Class RK1 current-limiting action is what lets it protect downstream gear with lower withstand ratings.
8) My motor keeps blowing the A2K20R on startup. What should I look at instead?
The Mersen A2K20R is a fast-acting Class RK1 fuse, which responds immediately to overcurrent and is not built to tolerate motor inrush. For a motor branch circuit, a time-delay fuse is the usual answer; the Littelfuse CCMR040 is a Class CC time-delay fuse rated 40A and is one such type. Confirm the required class, amperage and holder prep against the equipment nameplate and panel schedule before changing fuse types, since Class CC and Class RK1 mount differently.
9) Does the Mersen A2K20R meet RoHS for a facility spec?
Yes, the A2K20R is RoHS compliant. That is the compliance statement carried on the product, and it is usually what institutional and government procurement specs are checking for on fuses.
10) What part number do I order to standardize 20A 250V fuses across my control panels?
Order Mersen A2K20R. It is a single catalog number, 20A at 250VAC/250VDC, Class RK1 fast-acting, with no handing or finish options to specify. Stocking one number covers control panels, MCCs, lighting and HVAC distribution at that rating.
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Does the Mersen A2K20R come with a warranty?
Absolutely. The Mersen A2K20R is backed by a manufacturer’s warranty.
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