1-OFF-2-BOTH Rotary Marine Isolator Switch 500A Continuous 1600A Cranking Dual Battery Switch DC32V

Two banks and one dial is the oldest arrangement in boat electrics, and it still works because it is honest: you can see which battery you are running on. The MT074 gives you four marked positions — 1, OFF, 2 and BOTH — with a detent at each, so the choice is deliberate rather than something that drifts with vibration.

Inside, a copper bridge and stud terminals rated 500A continuous carry the everyday house load, with 700A available for five minutes and a 1,600A cranking burst for thirty seconds on a cold diesel. The shell is gray ABS with a sealed joint, so spray and dust stay out of the contact set.

• 500A continuous — The everyday figure and the one you size cable against. Fridge, lights, pumps and inverter can all sit here indefinitely.
• 700A for 5 minutes — For heavy manoeuvring loads — thrusters, winches, a long windlass pull — then back to continuous.
• 1,600A for 30 seconds — The cranking burst. Thirty seconds is generous for a diesel start, which is why this switch suits twin-engine boats and cold-climate work.

• Bank 1 positive to stud 1, bank 2 positive to stud 2 — The common output stud feeds the starter and the distribution panel. Keep the three cables the same cross-section.
• Fuse each bank separately — A fuse at the battery end of each positive cable protects the run between battery and switch, which the selector itself cannot do.
• Keep cable runs short and equal — Unequal lengths make one bank work harder in the BOTH position, which shortens the life of the pair.
• Mount on a rigid, dry surface — The rear base needs flat material; a flexing panel will loosen the stud nuts over a season.
• Torque all three studs, then load test — Check stud temperature by hand after the first loaded run; warmth is normal, heat is not.

MT074, 1-OFF-2-BOTH selector, gray shell, rated 500A continuous / 700A for 5 minutes / 1,600A cranking at DC 32V. There is no minimum order quantity — single units, samples and mixed containers are all accepted, with pricing quoted against quantity and packing. Standard production runs 30 days from deposit, T/T or Western Union with 30% down and the balance before shipment. Units ship in cartons; pallet and mixed-container lots can be quoted separately.

Tell us your bank sizes, cable cross-section and mounting position and we will confirm the MT074 configuration, packing and freight for your order — no minimum quantity required.

Tags: Marine Battery Isolator Switch / Marine Isolating Switch / Boat Isolator Switch