Blue Sea Systems ST-Blade Water-Resistant Fuse Block, 4 Circuit, 80A, 32V DC, IP66, ATO/ATC

Overview

The Blue Sea Systems ST-Blade Water-Resistant Fuse Block is a compact 4-circuit fuse block for protected DC branch circuits on boats, built for ATO and ATC blade fuses as well as ATO/ATC-style low-profile circuit breakers.

It is rated for 32V DC systems, with 80A maximum per block and 25A maximum per circuit. The tin-plated copper C11000 bus and fuse clips help keep electrical connections organized in damp marine spaces where corrosion control and clean wiring matter.

The block uses #8-32 screw terminals with captive star lock washers, accepts one 8 AWG to 4 AWG input wire and four 16 AWG to 10 AWG load wires, and has mounting holes with clearance for 1/4 in. or 6 mm screws. It works well for small DC distribution runs feeding electronics, pumps, lighting, accessories, and other fused loads where a covered, water-resistant installation is needed.

Key features

• Four fused branch circuits in a compact block for organized DC distribution on boats.
• 32V DC maximum rating with 80A total block capacity and 25A maximum per circuit.
• Accepts ATO and ATC fast-acting blade fuses, plus ATO/ATC-style low-profile circuit breakers.
• Water-resistant layout with three wire plugs included to help maintain the rating when fewer than four loads are installed.
• Tin-plated copper C11000 bus and fuse clips for electrical contact surfaces suited to marine wiring environments.
• #8-32 screw terminals with captive star lock washers for ring or spade terminals using standard tools.
• Single-side nesting layout lets wiring enter from one side, which helps reduce clutter in tight helm, console, locker, and service-panel spaces.
• Cover includes spare fuse and fastener storage, with four write-on circuit labels for quick circuit identification.

Variants

This fuse block is offered in two cover configurations. The electrical layout, circuit count, voltage rating, amperage rating, terminal type, bus material, and accepted fuse and breaker styles remain consistent across the variants.

The main difference is the cover style. Both versions keep the circuits covered, while the manual-cover version adds wing screws for tool-free cover access and is listed as meeting ABYC/USCG insulation requirements.

• 5056: Cover type standard. This version uses the standard cover configuration for installations where cover removal with normal service access is acceptable.
• 5056100: Cover type manual cover. This version uses a manual cover with wing screws, so the cover can be secured and removed without tools during inspection or fuse service.

Installation and setup

Mount the fuse block where the cover can be opened and the circuit labels can be read during service. The compact footprint and one-side wire entry are useful behind dashboards, inside consoles, under protected lockers, or near small accessory distribution points where wiring space is limited.

Use properly sized marine wire, crimped terminals, and circuit protection matched to each load. The block accepts one main input conductor from 8 AWG to 4 AWG and four load conductors from 16 AWG to 10 AWG, so it is best suited to grouped low-voltage branch circuits rather than large main distribution loads.

Compatibility and fit

This fuse block is for DC systems up to 32V and is suitable for both 12V and 24V boat electrical systems when the connected loads, wiring, and fuses are sized correctly. It accepts common ATO and ATC blade fuses, which makes replacement straightforward during routine maintenance or troubleshooting.

Fuses and circuit breakers are sold separately, so each circuit can be matched to the actual load on the boat. The included write-on labels help keep bilge pumps, electronics, lighting, washdown pumps, and accessory feeds easy to identify later.

Use cases on board

This fuse block is a good match for boat owners and installers adding a small group of protected circuits in an area exposed to spray, humidity, or routine washdown. It is especially useful where a standard uncovered fuse holder would leave wiring less organized or harder to service.

For refits, electronics additions, fishing accessories, cabin upgrades, or helm wiring cleanup, it gives each branch circuit a clear location, visible label, and covered fuse position without taking up much panel space.