​A4J150 – GOULD 150A 600V FAST ACTING FUSE

The A4J150 is a Class J fuse and must be installed in a Class J-rated fuse holder or fusible disconnect switch. Class J holders have a distinct blade configuration that prevents accidental substitution with lower-rated classes such as Class H or Class K. Using a non-Class-J holder is a code violation and a safety hazard.

The Gould A4J series has been transitioned through the Mersen (formerly Ferraz Shawmut) product line. Close direct equivalents include the Mersen AJT150, Littelfuse AJTR150, and Eaton/Bussmann JKS-150 — all Class J, 150A, 600V fast-acting fuses with a 200kA interrupting rating. Northern Breaker Group specialises in obsolete and hard-to-find fuses; contact us or request a quote and we'll source the right replacement for you.

The A4J150 is a fast-acting (non-time-delay) Class J fuse, which makes it well-suited for protecting capacitors, transformers, feeders, and bus systems, but it is generally not recommended as the sole branch-circuit protection for motor loads. Motors draw high inrush current on start-up, and a fast-acting fuse may open unnecessarily. For motor protection, a time-delay Class J fuse (such as the AJT series) is typically the correct choice. Always verify with the equipment manufacturer's specifications and applicable Canadian Electrical Code requirements.