The JBOX Model JB-1-NLAC is a purpose-built Automatic Power Transfer Switch (ATS) engineered specifically for navigation light systems aboard commercial and government vessels. Its primary function is to serve as a high-reliability electrical bridge between the vessel’s normal shipboard power supply — whether fed by the main generator, shore power connection, or ship’s service bus — and a designated secondary or emergency power source, such as an emergency battery bank, dedicated emergency generator, or UPS-backed bus. In the event of a blackout, brownout, or localized power failure affecting the normal supply, the JB-1-NLAC automatically detects the loss of voltage and seamlessly transfers the navigation light load to the emergency source without crew intervention, ensuring the vessel never goes “dark.”This is a critical safety and regulatory compliance function. Under the International Regulations for Preventing Collisions at Sea (COLREGs), a vessel is required to display the appropriate navigation lights from sunset to sunrise and during periods of restricted visibility. A power interruption that extinguishes navigation lights — even momentarily — creates a serious collision risk in congested waterways, traffic separation schemes, and during night transits. The JB-1-NLAC eliminates this risk by providing automatic, continuous monitoring of both power sources and instantaneous transfer switching when the primary source degrades or fails entirely.
The panel is designed for pilot house or wheelhouse bulkhead mounting, with a clean, low-profile face that integrates into existing bridge control layouts. It features two prominent status indicator lamps — a red “EMERG” lamp and a green “NORMAL” lamp — that give the Officer of the Deck (OOD) or watch officer immediate, at-a-glance confirmation of which power source is currently feeding the navigation light circuits. When the green lamp is illuminated, the vessel’s navigation lights are being supplied by normal shipboard power and all systems are operating as expected. When the red lamp illuminates, the panel has detected a loss of normal power and has automatically transferred to the emergency source — alerting the bridge team that a power casualty has occurred and that the secondary source is now carrying the navigation light load.
The inclusion of a lamp dimmer — a rotary potentiometer — allows the bridge watch to reduce the brightness of the panel’s indicator lamps during nighttime steaming, preserving the watch team’s night vision adaptation while still maintaining visibility of the panel’s status indicators. This is a practical and important feature for vessels operating in darkened-bridge conditions during night navigation.
The push-to-test function allows the crew to manually verify the operational readiness of the transfer switch and the availability of both power sources without waiting for an actual casualty to occur. This supports routine preventive maintenance checks, pre-voyage readiness inspections, and periodic USCG or classification society survey requirements. By pressing the test button, the watch team can confirm that the emergency source is live, that the transfer mechanism functions correctly, and that the status indicators respond appropriately — all without disrupting normal navigation light operation.
| Status Indicators | EMERG (Red Indicator Lamp): Illuminates when the panel has transferred the navigation light load to the emergency/secondary power source. Provides immediate visual alert to the bridge watch team that normal power has been lost and the backup source is active. The red color is chosen for urgency and rapid recognition in both daylight and darkened-bridge conditions. NORMAL (Green Indicator Lamp): Illuminates when the navigation light system is being fed by the vessel’s normal/primary shipboard power supply. Green indicates nominal, healthy operating status. When this lamp is lit, no crew action is required. |
| Controls | Push to Test (Momentary Button): A spring-return momentary contact button that allows the crew to manually initiate a transfer test sequence. This verifies the operational readiness of the automatic transfer mechanism, confirms the availability and voltage of the emergency power source, and validates correct indicator lamp response — all without interrupting navigation light service. Essential for pre-departure checks, routine PMS (Planned Maintenance System) actions, and survey preparation. Emergency Power in Use (Toggle Switch): Provides manual indication and/or override control related to the emergency power source’s active status. Allows the watch team to acknowledge or manually engage the emergency power feed in scenarios where automatic transfer may need to be supplemented by manual intervention. Emergency Power Available (Toggle Switch): Confirms the readiness and availability of the emergency/secondary power source. This switch enables the crew to verify or arm the emergency supply, ensuring the ATS has a viable backup source to transfer to in the event of a primary power loss. If the emergency source is offline for maintenance or is otherwise unavailable, this switch provides a clear status indication. Power Input Selection (Toggle Switch): Serves as the primary source selection control, allowing the crew to manually select between the normal and emergency power inputs. While the panel is designed for automatic transfer, this manual override capability is essential for maintenance scenarios, controlled power source testing, and situations where the crew may need to force-select a specific supply — for example, during generator changeovers or when deliberately running on emergency power for testing purposes. Normal Power Available (Toggle Switch): Confirms the presence and readiness of the normal/primary shipboard power source. Provides the crew with positive indication that the main supply is live and that the ATS is monitoring it for any voltage loss or degradation. Lamp Dimmer (Rotary Potentiometer): A continuously adjustable brightness control for the panel’s indicator lamps. Allows the bridge watch team to reduce indicator brightness during nighttime steaming to preserve night vision adaptation while maintaining panel readability. This is a standard and expected feature for any bridge-mounted panel aboard vessels that operate under darkened-bridge protocols during night navigation. |
| Total | 6 controls + 2 status indicators, providing fully automatic power transfer switching with comprehensive manual override and test capability, ensuring COLREG-compliant uninterrupted navigation light operation across all vessel operating conditions — from normal steaming to full blackout casualty recovery. |
JBOX Automatic Power Transfer Switch (ATS), specifically the Model JB-1-NLAC shown in the image. This unit is a critical fail-safe component, typically utilized to ensure uninterrupted power for a vessel’s navigation light system.
