A4BY500

The A4BY500 is a Class L, dual‑element, time‑delay current‑limiting fuse engineered for high‑performance overcurrent protection in low‑voltage power distribution systems. It is rated at 500 A and designed for use on circuits operating up to 600 VAC and 300 VDC, making it suitable for applications such as service entrance equipment, feeder circuits, load centers, panelboards, switchboards, and metering centers. The A4BY series is part of Mersen’s broader Amp‑Trap product family, known for combining robust current‑limiting capability with time‑delay characteristics that help accommodate normal inrush currents without nuisance opening.

Electrically, the A4BY500 fuse features a dual‑element design with a minimum time delay of approximately 4 seconds at 500 % of rated current, which allows harmless startup surges from motors and transformers to pass without opening, while still responding quickly to sustained overloads and short circuits. Its current‑limiting nature significantly reduces let‑through energy during fault events, protecting downstream equipment and coordinating with upstream protective devices. The fuse’s interrupting capacity is high—typically 200 kA at 600 VAC and 100 kA at 300 VDC—ensuring it can safely clear severe fault conditions in industrial and commercial environments.

Mechanically, the A4BY500 uses a blade‑type terminal and bolt‑on mounting for secure connection in compatible fuse blocks or holders. Its cylindrical body is made from a fiber/glass melamine material with silver‑plated copper terminals for durability and reliable electrical performance in harsh conditions. The unique dimensional profile of the A4BY series helps prevent incorrect replacements by other fuse classes, and stamped blade markings ensure clear identification during installation and maintenance. These design features, coupled with broad UL and CSA compliance, make the A4BY500 a dependable choice for utility, industrial, and commercial power protection applications.

Purchase the A4BY500 at Electrical.com, your reliable partner for industrial and commercial electrical products including fuses and accessories. Our selection includes manufacturers like Mersen, Ferraz Shawmut and Gould, backed by a dedicated sales team ready to assist with technical questions, product selection, and support.