A4J45 – GOULD 45A 600V FAST ACTING FUSE

The A4J45 is a standard Class J fuse, so it fits any Class J fuse holder or fusible disconnect rated for 600V and 45A or higher. Holders from Gould/Ferraz Shawmut, Eaton, Mersen, and other major manufacturers that meet the Class J specification are generally compatible. Always verify that the holder's voltage and ampere ratings meet or exceed the fuse ratings before installation.

The Gould A4J series has been carried forward through Ferraz Shawmut and later Mersen. Common modern equivalents include the Mersen AJT45 (time-delay) — note that the A4J series is fast-acting, so confirm the response type when cross-referencing. Eaton/Bussmann's JKS-45 is a comparable fast-acting Class J option. Northern Breaker Group specializes in obsolete and hard-to-find fuses; contact us for current stock and verified cross-references.

The 200kA interrupting rating means the A4J45 can safely clear fault currents up to 200,000 amperes without rupturing — a critical requirement in industrial and commercial panels fed from large transformers where available fault current can be very high. Using a fuse with an insufficient interrupting rating in a high-fault-current system is a serious safety hazard. Always verify the available fault current at the installation point against the fuse's rated interrupting capacity.