2-ALL-1-OFF Marine Isolator Switch 250A Continuous Rating Waterproof Battery Disconnect Switch

The MT334-B is a four-stage rotary isolator designed for dual-battery installations. Finished in black and built around a copper conductor path, it gives the operator four clear settings — battery 1, battery 2, both batteries combined, or everything off — from a single dial mounted on the dashboard or battery panel.

The copper internal contacts are the reason this unit is chosen for heavier marine and vehicle loads: copper carries current with lower resistance than plated steel, so terminals stay cooler during long charging sessions and the switch holds up better under repeated cycling. A 250A continuous rating with a 360A intermittent allowance covers engine cranking on most recreational craft and light commercial vehicles.

The sealed housing handles spray, rain and washdown, which matters on an open cockpit where the panel is routinely soaked. A 14 x 5 x 5 cm body keeps the footprint compact enough for tight helm consoles and battery lockers, and the black finish keeps it visually unobtrusive on a dark dashboard.

• Copper conductor path — lower resistance and less heat build-up than plated steel contacts.
• Black sealed housing — resistant to spray, rain and hose-down cleaning while staying visually discreet.
• Four-stage rotary dial — 2-ALL-1-OFF gives independent bank selection or combined output as needed.
• 250A continuous / 360A intermittent — sized for cranking duty plus accessory load on 12V and 24V systems.
• Reinforced stud terminals — accept ring lugs and stay tight under engine vibration.
• Compact 14 x 5 x 5 cm body — fits helm consoles and battery boxes without a redesign.

• 1 — battery 1 connected, battery 2 isolated. The usual setting for using the start bank alone.
• 2 — battery 2 connected, battery 1 isolated. Useful when running from the house bank at anchor.
• ALL — both banks joined, ideal for a combined cranking boost or to let one charging source top up both batteries.
• OFF — everything isolated, the setting to use before storage, service work or leaving the craft unattended.

• Isolate both batteries and disconnect negatives before starting any wiring.
• Mount the body on a flat, dry surface with enough clearance for the dial to rotate through all four positions.
• Run battery 1 positive to terminal 1 and battery 2 positive to terminal 2; connect the load or starter feed to the common terminal.
• Fit ring lugs to every cable and torque the stud nuts firmly — loose terminals are the main cause of heat at the switch.
• After wiring, test each dial position with a meter before reconnecting any loads.

• Boats and yachts — start and house bank selection, master isolation before mooring.
• RVs and campers — leisure and vehicle battery management with a combined-boost option when needed.
• Cars, 4x4s and light commercial — dual-battery set-ups for fridges, winches and work equipment.
• Industrial and marine service — battery isolation on workboats, compressors and mobile plant.

• Minimum order — 5 pcs.
• Price — negotiable, quoted against quantity and configuration.
• Capacity — 5000 pcs per month.
• Lead time — 30 days for standard production.
• Payment — T/T or Western Union; 30% deposit with the balance before shipment.
• Packing — neutral white box inside a brown export carton; branded packing available with written trademark authorisation.
• Incoterms — EXW, FOB, CFR, CIF and DDU.