The 04511.25NRL comes in a 2-SMD square end block package measuring 0.240" x 0.106" x 0.106" (6.10 mm x 2.69 mm x 2.69 mm). Surface-mount footprint means the fuse sits flush on the board — no through-hole leads to route, but the pad geometry must match the end-block terminations for reliable solder wetting and to keep the DC cold resistance at the listed 0.078 Ohms. This is a Tape & Reel (TR) delivery format, so it feeds directly into a pick-and-place line. The NANO² 451 series is the identity here — a compact SMD fuse family designed for dense PCB layouts where a cartridge-style fuse won't fit.
What the ratings mean for your BOM
Rated 1.25 A continuous with a fast-blow response — this fuse opens quickly on overcurrents above the threshold, protecting downstream components from short-circuit energy. The 125 V AC and 125 V DC rating is the same on both sides, so it works in single-supply DC rails or AC line-side circuits up to that voltage. Breaking capacity is 50 A at the rated voltage. That means it can safely interrupt a fault current up to 50 A without rupturing or arcing across the package — critical for clearing hard shorts on a 125 V rail where the available fault current from a bulk capacitor bank or power supply could exceed the fuse's interrupt rating. Melting I²t is 0.664 — this is the energy needed to melt the fuse element. Use it to coordinate with downstream semiconductors: the I²t of the fuse should be below the I²t withstand of the protected device (like a diode or FET) to ensure the fuse clears before the component fails short.
Compliance and approvals
Approved by CSA, PSE, and UL — these are the primary safety certifications for North American and Japanese markets. UL recognition means the fuse is tested to UL 248-14 for supplemental overcurrent protection; CSA and PSE cover Canadian and Japanese electrical safety standards respectively.