Blue Sea Systems offers a comprehensive range of high-quality marine electrical products. Their products include fuse panels, terminal fuses, distribution blocks, battery management systems, switches, circuit protection, and more. These products are designed to enhance the safety, reliability, and efficiency of electrical systems on boats and yachts. Blue Sea Systems' fuse panels and distribution blocks help organize and protect wiring, while their battery management solutions ensure proper power distribution and control. Their switches, voltmeters, and other components provide easy monitoring and control of onboard electrical systems. Overall, Blue Sea Systems' products contribute to the smooth operation and safety of marine electrical systems.
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1-2 weeks delivery time The Blue Sea 5001 is a MEGA® / AMG® fuse block for 32V DC systems, designed to accept 100–300A fuses (sold separately). It uses 5/16" (M8) stainless steel studs and includes an insulating cover that meets ABYC and USCG requirements, with multi-directional wire access and high-torque terminals for secure electrical connections.
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$ 42.12
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1-2 weeks delivery time The Blue Sea 5006100 MAXI Fuse Block is rated up to 80A and 32V DC and supports 14–4 AWG wiring with screw terminals torqued to 25 in-lb (2.82 Nm). It features a snap-on insulating cover, ignition protection, side or bottom wire entry breakouts, and terminal screws that compress fuse blades for low-resistance connections. Mounting uses #10 screws. Weight: 0.25 lb (0.11 kg).
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$ 49.84
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1-2 weeks delivery time The Blue Sea 5015 is a 6-circuit ST glass fuse block for 12–32V DC systems with an integrated negative bus and insulating cover. It supports AGC and MDL (3AG) glass fuses with a rating of 30A per circuit and 100A per block. The clear cover insulates all conductive parts to meet ABYC and USCG requirements and provides label recesses and spare fuse storage.
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$ 89.70
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1-2 weeks delivery time The Blue Sea 5021 is a water resistant panel-mount fuse holder designed for AGC and MDL fuses, rated up to 20A (depending on fuse and wire sizing). It is easy to open and built to withstand typical above-deck water exposure including salt spray, rain, hose washdowns, and momentary immersions. The holder installs in a 0.50in (12.7 mm) mounting hole and has a compact weight of 0.02 lb (0.01 kg), making it a practical replacement for fuse holders used in Contura Waterproof Fuse Panels.
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$ 7.63
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1-2 weeks delivery time The Blue Sea 5023 ST Blade Battery Terminal Mount Fuse Block is a 4-circuit ATO®/ATC® fuse block designed to mount directly on a battery terminal stud (clearance for 3/8" [M10]). Rated for up to 32V DC, it supports 100A per block and 30A per circuit (depending on fuse and wire sizing). It includes an insulating cover, four nylon insulated ring terminals, and one 15A ATO/ATC fuse (PN 5242).
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$ 44.39
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1-2 weeks delivery time The Blue Sea 5024 ST Blade Battery Terminal Mount Fuse Block Kit adds 4 fused ATO®/ATC® circuits directly at a battery terminal using a 3/8" (M10) stud mount. Rated up to 32V DC, it supports 100A per block and 30A per circuit (depending on fuse and wire sizing) and includes an insulating cover, 4-circuit negative busbar, write-on labels, and nylon insulated ring terminals (four 16–14 AWG and four 12–10 AWG). It is Ignition Protected and meets ISO 8846 and SAE J1171.
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$ 63.34
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1-2 weeks delivery time The Blue Sea 5025 ST Blade Fuse Block provides 6 ATO®/ATC® fused circuits with a built-in negative bus and insulating cover for organized branch circuit protection up to 32V DC. It supports 100A per block and 30A per circuit (depending on fuse and wire sizing) and uses #10-32 studs for both positive and negative distribution. The cover meets ABYC/USCG insulation requirements, includes an easy-open latch, storage for two spare fuses, and label recesses for Small Format Labels (with 20 write-on circuit labels included).
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$ 82.68
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1-2 weeks delivery time The Blue Sea 5028 ST Blade Fuse Block provides 6 ATO®/ATC® fused circuits with an insulating ABYC/USCG-compliant cover for clean branch circuit protection up to 32V DC. It supports 100A per block and 30A per circuit (depending on fuse and wire sizing) and uses a #10-32 positive bus stud with #8 screw (M4) mounting. The cover includes a push-button latch, storage for two spare fuses, and label recesses for Small Format Labels, with 20 write-on circuit labels included.
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$ 72.47
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Blue Sea 5029 - ST Blade Fuse Block, 12 Circuits with Cover, 32V DC, 100A per Block, 30A per Circuit
1-2 weeks delivery time The Blue Sea 5029 ST Blade Fuse Block provides 12 ATO®/ATC® fused circuits with an insulating ABYC/USCG-compliant cover for organized DC branch circuit protection up to 32V DC. It supports 100A per block and 30A per circuit (depending on fuse and wire sizing) and uses a #10-32 positive bus stud with #8 screw (M4) mounting. The cover features a push-button latch, storage for two spare fuses, and label recesses for Small Format Labels, with 20 write-on circuit labels included.
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$ 93.14
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1-2 weeks delivery time The Blue Sea 5032 ST Blade Split Bus Fuse Block provides 12 ATO®/ATC® fuse circuits in two isolated 6-circuit groups, designed for systems needing a mix of switched and 24-hour circuits or two isolated batteries. Rated up to 32V DC, it supports 30A per circuit with 100A total (not to exceed 80A per load group). It includes a negative bus with #10-32 stud, a clear ABYC/USCG-compliant insulating cover with fuse storage and label recesses, and #8-32 screw terminals (fuses sold separately).
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$ 150.39
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1-2 weeks delivery time The Blue Sea 5037 ST Blade Fuse Block provides 6 independent ATO®/ATC® fused circuits for DC systems up to 32V DC, rated 30A per circuit and up to 40A per jumped circuit group. It features tin-plated copper fuse clips for corrosion resistance, reduced heat, and improved electrical efficiency, and mounts with #8 screws (M4). The block accepts ring or snap fork terminals and includes two terminal block jumpers (fuses sold separately).
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$ 66.59
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1-2 weeks delivery time The Blue Sea 5045 ST Blade Compact Fuse Block provides 4 ATO®/ATC® fused circuits in a compact surface-mount design with single-side wire entry to minimize footprint. Rated up to 32V DC, it supports 100A per block and 30A per circuit (depending on fuse and wire sizing), includes an ABYC/USCG-compliant insulating cover, and is Ignition Protected when the cover is secured (ISO 8846 / SAE J1171). Built with tin-plated copper buses and fuse clips, it accepts ring or snap fork terminals and includes 4 write-on circuit labels (fuses sold separately).
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$ 60.21
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1-2 weeks delivery time The Blue Sea 5046 ST Blade Compact Fuse Block provides 8 ATO®/ATC® fused circuits in a compact surface-mount design with single-side wire entry to reduce installation footprint. Rated up to 32V DC, it supports 100A per block and 30A per circuit (depending on fuse and wire sizing), includes an ABYC/USCG-compliant insulating cover, and is Ignition Protected when the cover is secured (ISO 8846 / SAE J1171). It uses tin-plated copper buses and fuse clips, accepts ring or snap fork terminals, and includes 8 write-on circuit labels (fuses sold separately).
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$ 96.02
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1-2 weeks delivery time The Blue Sea 5052 ST CLB Circuit Breaker Block provides 6 resettable CLB circuit breaker positions with integrated positive and negative bus using #10-32 studs, rated up to 32V DC. It supports 100A per block and 32A per circuit (depending on wire sizing) and uses snap-in quick connect clips for easy breaker installation. The block mounts using #8 screw (M4) or #8 nut, has 5.63in (143 mm) mounting centers, a height of 6.69in (169.93 mm), and operates from -10°C to 60°C.
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$ 105.61
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1-2 weeks delivery time The Blue Sea 5056 ST-Blade Water-Resistant Fuse Block provides compact water-resistant circuit protection for ATO/ATC fuses and ATO/ATC-style low profile circuit breakers, rated up to 32V DC with 80A per block and 25A per circuit. It uses tin-plated copper C11000 bus material, supports (1) 8–4 AWG input and (4) 16–10 AWG load wiring, and mounts with clearance for 1/4" (6 mm) screws. The cover includes spare fuse/fastener storage and comes with four write-on circuit labels and 3 wire plugs to maintain the water-resistant rating when fewer than 4 loads are used (fuses and breakers sold separately).
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$ 68.10
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1-2 weeks delivery time The Blue Sea 5060 Crimpable In-Line AGC/MDL Fuse Holder is designed for 12–18 AWG wire and supports a maximum 30A fuse (fuse sold separately). It provides a compact inline fuse holder solution for AGC or MDL fuses and weighs 0.03 lb (0.01 kg).
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$ 5.42
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1-2 weeks delivery time The Blue Sea 5061 Waterproof In-Line AGC/MDL Fuse Holder is designed for 12–16 AWG wire and supports a maximum 30A fuse (fuse sold separately). This inline fuse holder accepts AGC and MDL fuses and is listed with a weight of 0.1 lb (0.05 kg) and 0.03 lb (0.01 kg).
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$ 10.68
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1-2 weeks delivery time The Blue Sea 5064 In-Line ATO/ATC Fuse Holder is designed for use with ATO or ATC blade fuses and is supplied with 12 AWG pigtails for straightforward installation. It supports a maximum 30A fuse amperage (fuse sold separately) and has a weight of 0.03 lb (0.01 kg).
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$ 6.84
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1-2 weeks delivery time The Blue Sea 5065 Waterproof In-Line ATO/ATC Fuse Holder is designed for ATO or ATC blade fuses and is supplied with 12 AWG pigtails for fast installation. It supports a maximum 30A fuse amperage (fuse sold separately) and weighs 0.03 lb (0.01 kg).
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$ 17.23
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1-2 weeks delivery time The Blue Sea 5101 MEGA® / AMG® Fuse (100A) is an economical solution for 100–300A circuit protection applications when used with AMG® fuse blocks. It is rated 100A, 70V DC, and is Ignition Protected (Yes), with an interrupt capacity of 2000A @ 32V DC. The fuse weighs 0.06 lb (0.03 kg) and is compatible with all AMG fuse blocks, including the 7721 AMG® Safety Fuse Block.
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$ 18.49
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What are the key components and features of a Blue Sea Systems add-a-battery dual circuit system, and how does it contribute to effective battery management on boats?
A Blue Sea Systems add-a-battery dual circuit system is a comprehensive solution designed for efficient battery management on boats and yachts. It includes key components such as an Automatic Charging Relay (ACR), distribution blocks, switches, fuses, and terminal blocks. The system allows seamless switching between battery banks, prioritizing charging and isolating them when necessary. This setup optimizes power distribution, prevents battery drain, and ensures reliable starting power. The dual circuit system is a fundamental tool in maintaining electrical integrity and uninterrupted power supply on marine vessels.
By integrating a Blue Sea Battery Switch, users gain a reliable and safe method to manually control power flow between battery banks. This switch is built to marine-grade standards, ensuring long-term durability in harsh environments.
How does a Blue Sea Systems SI-ACR (Automatic Charging Relay) function, and what benefits does it offer for maintaining optimal battery charging and isolation?
The Blue Sea Systems SI-ACR (Automatic Charging Relay) is a key component in advanced Marine Wiring systems, designed to simplify and optimize the management of multiple battery banks on boats and yachts. It functions by automatically connecting battery banks during charging—when voltage exceeds a preset threshold—and isolating them when charging stops or voltage drops.
For a complete power distribution and protection solution, pair the SI-ACR with a robust Blue Sea Fuse Block.
What is the purpose of a Blue Sea Systems MRBF (Terminal Fuse) and how is it utilized in marine electrical systems to ensure safety and protection?
The Blue Sea Systems MRBF (Terminal Fuse) is a crucial component in marine electrical systems designed to provide protection against overcurrent situations. It safeguards electrical circuits and equipment by interrupting the flow of current in the event of a fault or excessive current draw. These fuses are engineered to handle high current loads and are typically installed in close proximity to batteries, making them a critical element in systems that require high reliability and safety.
Often used alongside Blue Sea Add a Battery systems, MRBF fuses ensure consistent protection and help maintain the integrity of the overall electrical setup. Their compact design and high interrupt capacity make them ideal for marine environments, where space is limited and safety is paramount.
To further enhance electrical safety and efficiency, integrating a Blue Sea Terminal Block provides organized and secure connections, optimizing the performance and reliability of marine electrical installations.