Blue Sea Systems 187-Series Switchable Thermal Circuit Breaker, 48V DC, Type III, Trip-Free, Ignition Protected

Overview

The Blue Sea Systems 187-Series is a switchable thermal circuit breaker for DC marine circuits where circuit protection and a manual reset switch need to sit in the same accessible device. This 48V DC breaker family covers amperage ratings from 25A to 200A, with panel-mount and surface-mount versions for different electrical layouts on board.

Each breaker uses a thermally responsive bi-metal blade and Type III switchable manual-reset operation. The trip-free mechanism means the lever cannot be held closed against a fault, which matters on battery feeds, windlass circuits, inverter feeds, charging circuits, and other DC loads where fault current needs to be interrupted safely.

The range uses 5/16 inch-18 terminal studs, accepts #10 or M5 mounting screws, and has published interrupt ratings of 5000A at 14V DC, 3000A at 28V DC, and 1500A at 48V DC. The operating temperature range is -40 C to 85 C, giving it room for engine room heat, exposed lockers, and colder storage conditions.

Key features

• Combines DC circuit protection and manual switching in one breaker for circuits that need accessible shutoff and reset.
• 48V DC maximum voltage rating, with amperage options from 25A to 200A across the range.
• Type III switchable manual-reset operation with a trip-free mechanism that cannot be held closed during a fault.
• Panel-mount and surface-mount configurations support different helm panels, electrical lockers, battery compartments, and distribution layouts.
• 5/16 inch-18 terminal studs give high-current cable lugs a secure termination point.
• Large clearance around the terminal studs helps accommodate heavy gauge wire lugs used on higher-amperage DC circuits.
• Interrupt capacity is rated at 5000A at 14V DC, 3000A at 28V DC, and 1500A at 48V DC.
• Ignition protected to SAE J1171 for installation aboard gasoline-powered boats.
• Thermoset polyester case material supports use in demanding marine electrical spaces.

Variants

This range varies by mounting style and amperage. The available configurations include panel-mount and surface-mount versions, with ratings from 25A through 200A to match the protected circuit and the cable size selected for the installation.

The breaker family remains a 48V DC switchable thermal breaker with manual reset and trip-free operation across the range. Select the mounting format that matches the physical location of the breaker, then match the amperage to the circuit protection requirements of the equipment and wiring.

Installation and setup

Panel-mount versions suit installations where the breaker face is intended to be visible and reachable through a panel. Surface-mount versions are useful where the breaker needs to be installed directly onto a bulkhead, backing board, or electrical mounting surface without building it into a finished panel.

The breaker should be placed where the lever can be reached for reset and isolation, while keeping cable runs practical and protected. As with any high-current DC circuit, the breaker rating must be coordinated with the conductor size, expected load, voltage drop plan, and the equipment manufacturer’s requirements.

Electrical and system integration

The 187-Series is commonly used in DC distribution where a fuse alone is less convenient because the circuit also benefits from a visible lever and manual reset. The lever gives a clear indication of breaker status and allows the circuit to be opened for service without removing a fuse.

For circuits with heavy startup current, confirm the breaker rating and trip behavior against the load profile before installation. Motors, windlasses, pumps, chargers, and inverter circuits can draw inrush current that needs to be considered during circuit protection planning.

Use cases on board

This breaker family is a practical match for boat owners, technicians, and builders working on DC electrical systems that need serviceable protection in a compact mounting footprint. It fits well in battery compartments, DC distribution panels, equipment lockers, and other locations where a resettable breaker is easier to manage than replacing a fuse.

Orders are processed within 2 business days, which includes verification, packing, and dispatch. Orders of $100 or more qualify for free shipping when eligible. For orders under $100, shipping costs are calculated at checkout based on destination, package weight, and selected service. International shipping is available for eligible products, and certain items may require additional handling, warehouse transfers, or may ship directly from the manufacturer, which can affect processing time.

Deliveries are handled by preferred carriers such as USPS, UPS, FedEx, DHL, and others depending on your location and selected service. Estimated delivery times are displayed at checkout and may vary due to customs processing, carrier delays, weather, postal disruptions, or other circumstances beyond our control. Once your order ships, you'll receive a confirmation email with tracking information. Tracking may take up to 24 hours to update on the carrier's website and is also available through your account when applicable.

We ship throughout the United States and to most international destinations for products eligible for international shipping. International orders may be subject to customs duties, taxes, brokerage charges, or other import fees, which are the customer's responsibility and are not included in the product or shipping price. PO Boxes are accepted only when shipping through USPS, and not all packages qualify for this option. If your order does not arrive within the estimated delivery window, please contact us at info@apollolighting.com or +1 (954) 375-0100 so we can assist with locating your package.

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Returns may be requested within 30 days of receiving your order. Items must be unused, uninstalled, unaltered, and returned in their original packaging with all tags, packing materials, blank warranty cards, manuals, instructions, accessories, and included items. Certain products, including installed or used electronics, electrical components, lighting, consumables, custom or special-order items, cut-to-length products, safety equipment, and merchandise exposed to water or marine conditions, may not be eligible for return.

To request a return, sign in to your account and select the applicable order and items, and submit your request for review. Eligible unfulfilled items may also be submitted for cancellation within 1 hour of placing the order. Returns or cancellations are not considered approved until you receive confirmation from Apollo Lighting. Please do not ship or drop off merchandise before receiving return approval and instructions.

Customers are responsible for arranging and paying for return shipping unless the return is due to an error by Apollo Lighting or the item is verified as defective, damaged, or incorrect. Missing, damaged, defective, or incorrect items must be reported within 2 business days of delivery, and photos or other documentation may be required for review. If the issue is verified, Apollo Lighting may provide or reimburse return shipping and issue a replacement or refund depending on the circumstances. International customers are responsible for return shipping, duties, taxes, customs charges, brokerage fees, and other costs associated with an international return.

After your return is received and inspected, approved refunds are issued to the original payment method and may take 5-7 business days to appear after processing. Original shipping and handling charges are nonrefundable, and the value of any included free items that are not returned may be deducted from the refund. Apollo Lighting does not charge a standard restocking fee on eligible returns. Returns that are incomplete, damaged, installed, used, altered, improperly packaged, or otherwise do not meet the eligibility requirements may be refused. We recommend using a trackable and appropriately insured shipping service for all customer-arranged returns.

For assistance, contact info@apollolighting.com or call +1 (954) 375-0100.

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Many products sold by Apollo Lighting include a manufacturer's warranty covering defects in materials or workmanship. Warranty terms vary by brand, product category, and model, so eligibility, coverage duration, exclusions, and available remedies are determined by the applicable manufacturer. We recommend reviewing the warranty information provided with your product before installation or use, especially for marine electronics, navigation equipment, lighting, electrical systems, pumps, safety equipment, and other specialized marine products.

If you need warranty service, the claim must follow the process established by the manufacturer, authorized service center, or designated warranty provider. You may be asked for proof of purchase, a serial number, product registration, photos, maintenance or installation records, or other documentation. Apollo Lighting does not determine or modify a manufacturer's warranty coverage or final claim decision, but we are happy to help provide purchase information and direct you to the appropriate manufacturer or warranty resource.

Keep your receipt, product documentation, serial number information, and original packaging when practical. Damage caused by normal wear, misuse, improper installation, insufficient maintenance, corrosion, impact, unauthorized modifications, electrical issues, or operation outside the manufacturer's specifications may not be covered. Warranty claims are separate from standard returns, so a product that has been installed, used, or exposed to marine conditions may no longer qualify for return while still remaining eligible for evaluation under the manufacturer's applicable warranty.

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