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50 Amp 600 Volt Fast Acting Class J Fuse · Ferraz Shawmut Mersen A4J-50
SKU: MER-A4J-50
Fast-acting Class J ferrule fuse rated 50A at 600VAC and 300VDC for current-limiting branch circuit protection in industrial and commercial equipment. Commonly used where fast response is needed to protect sensitive components and reduce let-through energy.
What this product is for
This Class J fast-acting fuse is used for overcurrent protection in industrial and commercial electrical equipment where rapid fault clearing is required. It is suited to branch circuit protection for equipment that benefits from current-limiting performance.
Use for
Use for control panels, disconnects, motor and transformer circuits where the design calls for a 50A Class J fuse with a 600VAC rating. It is also used where compact ferrule-style Class J fuses are specified.
Avoid for
Avoid using this fuse where a time-delay fuse is required for high inrush loads, or where the equipment nameplate calls for a different fuse class, amp rating, voltage rating, or interrupting rating.
Best for
Best for electricians and maintenance teams replacing an existing A4J series fuse or specifying fast-acting Class J protection for sensitive equipment. The Class J rejection feature helps prevent substitution with the wrong fuse class.
Installed in
Typically installed in Class J fuse blocks, safety switches, and industrial distribution equipment in commercial buildings, manufacturing facilities, and OEM panels.
Why this product exists
This fuse exists to clear overcurrent and short-circuit faults quickly while limiting let-through current and energy to downstream equipment. Fast-acting Class J fuses are commonly selected where equipment protection is prioritised over temporary inrush tolerance.
Compared with similar products
Compared with time-delay Class J fuses, this fast-acting model responds more quickly to fault conditions but is less suitable for circuits with frequent startup surges. Compared with lower interrupting rating fuses, this model is intended for higher available fault current applications when used within its listed ratings.
Specifications
- Manufacturer part number: A4J-50
- Brand: Mersen
- Series: Amp-Trap A4J
- Product type: Fast-acting Class J fuse
- Current rating: 50A
- Voltage rating: 600VAC, 300VDC
- Body style: Ferrule
- Interrupting rating: 200 kA AC, 100 kA DC
- Frequency: 50/60 Hz
- Typical application: Current-limiting branch circuit protection
- Trade note: Class J fuses use rejection-style dimensions and must match the fuse holder class.
- ApplicationCurrent-limiting branch circuit protection
- Voltage600VAC, 300VDC
- SeriesAmp-Trap A4J
- Frequency50/60 Hz
- Body StyleFerrule
- Interrupting Rating200 kA AC, 100 kA DC
- Current Rating50A
- Trade NoteClass J fuses use rejection-style dimensions and must match the fuse holder
- BrandsFerraz Shawmut Mersen
Aptico Supply Delivery
Fast Electrical Supply Delivery Across Ontario
Local delivery routes, pickup options, and contractor-focused service from our Elmira and Flesherton locations.
Delivery Built Around Electrical Contractors
Aptico Supply helps electricians, contractors, and commercial buyers get the electrical materials they need without unnecessary delays. Whether you are ordering for a jobsite, restocking service inventory, or arranging pickup, our delivery options are designed to keep work moving.
Free Daily Delivery
Free daily delivery is available for larger contractor accounts.
- Order by 9:00 AM for morning delivery
- Order by 2:00 PM for afternoon delivery
- Available in qualifying local delivery areas
Free Weekly Delivery
Free weekly delivery is available for smaller accounts in select service areas.
- Elmira area delivery: Tuesday
- Flesherton area delivery: Thursday
- Order by 11:00 AM on the route day
Pickup Options
Pickup is available from our Ontario locations for customers who prefer to collect their order directly.
- Elmira pickup available
- Flesherton pickup available
- Call ahead for large or special-order items
Local Delivery Areas
See our local delivery coverage below. Delivery charges may apply outside regular route areas or for oversized items.
Delivery Questions
Do you offer free delivery?
Yes, free delivery is available for qualifying contractor accounts and selected local delivery routes.
Can I pick up my order?
Yes, pickup is available from our Elmira and Flesherton locations.
Do delivery charges apply?
Delivery charges may apply outside regular local routes, for smaller orders, or for oversized and heavy items.
Can you deliver to jobsites?
Yes, jobsite delivery may be available depending on the order size, location, and delivery schedule.
Need Electrical Supplies Delivered?
Contact Aptico Supply to confirm your delivery options, pickup availability, or contractor account eligibility.
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