Blue Sea Systems ST Blade Compact Fuse Block, 100A, 32V DC, ATO/ATC

Overview

The Blue Sea Systems ST Blade Compact Fuse Block is a surface-mount fuse block for consolidating ATO and ATC blade-fuse branch circuits in a compact boat electrical panel. It is rated for up to 100A per block and 30A per circuit, with a maximum voltage of 32V DC, making it appropriate for common 12V and 24V DC marine distribution work.

This fuse block is useful when electronics, pumps, lighting, accessories, or other low-voltage DC loads need organized protection without a row of separate in-line fuse holders. The single-side wiring layout lets conductors enter from one side, which helps in tight helm consoles, lockers, cabin panels, and engine-room electrical spaces where clean service access matters.

With the cover secured, the block is ignition protected for gasoline engine compartments under ISO 8846 and SAE J1171. The insulating cover also supports ABYC and USCG insulation requirements, while tin-plated copper buses and fuse clips help maintain good conductivity in damp marine environments.

Key features

• Accepts ATO and ATC fast-acting blade fuses for common marine DC branch circuits.
• Available in 4-circuit and 8-circuit configurations for different panel sizes and accessory counts.
• Rated to 100A per block, 30A per circuit, and 32V DC for 12V and 24V boat systems.
• Single-side wire entry helps reduce the footprint inside small consoles, lockers, and distribution panels.
• Ignition protected when the cover is secure, with ISO 8846 and SAE J1171 compliance for gasoline engine compartment use.
• Insulating cover meets ABYC and USCG insulation requirements for safer exposed-terminal protection.
• Tin-plated copper buses and fuse clips support clean current flow and help resist corrosion.
• Accepts ring terminals or snap fork terminals for flexible wiring during new installations or refits.
• Uses #8 screw mounting, #8-32 screw terminals with captive star lock washers, and a #10-32 terminal stud.
• Fuses are sold separately, allowing each circuit to be fused to the load and wire size used on board.

Variants

This ST Blade Compact Fuse Block is offered in two circuit-count configurations. Both versions use the same compact common-source fuse block concept for ATO and ATC blade fuses.

The main difference between the variants is the number of protected branch circuits. The current ratings, 32V DC maximum voltage, ignition-protected construction with the cover secured, terminal style, and single-side wiring layout remain consistent across the two configurations.

• 5045: 4-circuit configuration. This version keeps four fused branch circuits grouped in a small footprint, which works well for focused accessory panels, compact helm upgrades, or limited DC distribution additions.
• 5046: 8-circuit configuration. This version doubles the number of available fused circuits while keeping the same compact wiring approach, which helps when several electronics, lighting, pump, or accessory circuits need to be organized in one location.

Installation and fit

The block mounts with #8 screws or M4 hardware on a flat surface. The single-side entry layout is helpful when the fuse block is placed along the edge of a panel or bulkhead, since the wiring can be dressed from one direction rather than crossing around the block.

Terminals should be matched to the conductor size and circuit load, using ring or snap fork terminals as appropriate. The terminal stud torque is 24 in-lb, and the screw terminal torque is 18 in-lb, so installation should be tightened carefully without overloading the hardware.

Electrical and system integration

This is a common-source fuse block, so it is used for positive DC branch-circuit distribution rather than for combined positive and negative bus organization. Each branch circuit should use an ATO or ATC fuse sized for the connected load and the installed wire gauge.

For serviceability, the write-on circuit labels help identify each protected circuit at a glance. That matters on boats where quick troubleshooting at the dock or underway can save time, especially around navigation electronics, pumps, lighting, communications gear, and accessory loads.

Use cases on board

The 4-circuit version is a good match for smaller accessory additions or a focused sub-panel, while the 8-circuit version suits a larger group of fused DC loads in one place. Both versions fit well in refits where older in-line fuse holders need to be replaced with a cleaner and easier-to-service layout.

Because the unit is ignition protected when the cover is secured, it can be used in gasoline engine compartment applications where the installation otherwise follows the vessel’s electrical layout and applicable marine wiring practices.