Blue Sea Marine Fuse Blocks: ATO/ATC, Inline & MRBF Guide

Fuse blocks organize and protect marine and RV DC circuits, but not every fuse holder performs the same job. Blue Sea's ST Blade models distribute several ATO/ATC fused circuits; the 5062 holds an in-line AGC/MDL fuse, and the 5191 mounts a marine-rated battery fuse near a power connection. Use this exact-MPN comparison to choose the appropriate format.

Choose the right type of circuit protection

ATO/ATC blade blocks

Distribute several fused accessory circuits from a common supply. Available in this selection with or without negative buses.

AGC/MDL in-line

A single glass-fuse holder that is installed along a suitable protected conductor, not a multi-circuit panel.

MRBF terminal holder

Mounts a marine-rated high-current fuse near an appropriate battery or distribution connection.

Blue Sea ST Blade fuse block comparison

The ST Blade models listed below use ATO/ATC fast-acting blade fuses. Manufacturer block ratings are up to 100 A total, 30 A per circuit and 32 V DC; the fuse and wire must be correctly sized for the actual installation.

Blue Sea model Design Circuits Fuse style Negative bus Cover
5024 Battery-terminal ST Blade kit 4 ATO/ATC blade Negative bus included Yes
5025 ST Blade with negative bus 6 ATO/ATC blade Yes Yes
5026 ST Blade with negative bus 12 ATO/ATC blade Yes Yes
5028 ST Blade, positive distribution 6 ATO/ATC blade No Yes
5029 ST Blade, positive distribution 12 ATO/ATC blade No Yes
5030 ST Blade with negative bus 6 ATO/ATC blade Yes No

5024 is a special battery-stud-mounted four-circuit kit, not the same mounting format as a screw-mounted fuse block. The base manufacturer part numbers appear with a -BSS suffix in these store listings.

In-line glass and battery-terminal MRBF holders

Blue Sea model Design Fuses held Fuse type Return bus Protection
5062 Waterproof in-line fuse holder 1 AGC / MDL glass N/A Enclosed holder
5191 Battery-terminal MRBF holder 1 MRBF terminal fuse N/A Insulating cap

The 5062 in-line AGC/MDL holder is rated for a maximum 20 A fuse and accepts 12–16 AWG wire. The 5191 MRBF holder is rated up to 58 V DC and 300 A, with an M8 terminal connection; the MRBF fuse is separate.

Important selection and installation checks

Calculate branch loads and size each fuse and conductor to protect the wiring, not merely to match the fuse holder's maximum rating. Follow the manufacturer's instructions for mounting, bus feed protection, connector torque and enclosure requirements. A negative bus does not replace an appropriately designed grounding system.

Fuse block rating is not the correct fuse size for every circuit

Choose the actual ATO/ATC, AGC/MDL or MRBF fuse separately to match the equipment and conductor-protection requirements. The 5191 holder's 300 A rating does not mean a 300 A fuse is suitable for every installation.

Blue Sea marine fuse blocks and holders

Open the exact part number for product details and availability.

More electrical installation guides

Marine battery disconnect switches and covers · Ancor ring terminals by stud size

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