OEX ACX3409 Battery Master / Isolation Switch On/Off SPST

OEX ACX3409 75A Battery Master Isolation Switch Keyed On/Off SPST Two 8mm Stud Terminals 24mm Panel Mount

The OEX ACX3409 is a keyed battery master isolation switch rated at 75A continuous at 12V, with a two-position On/Off SPST configuration. A battery master switch provides a single point of disconnect between the battery and the vehicle's electrical system essential for safe servicing, extended storage, fire risk reduction and anti-theft security. The key is removable only in the Off position, meaning the battery cannot be reconnected without the key. Two 8mm stud terminals for the main power circuit. 24mm mount diameter, 33mm mount length. Replacement key available as OEX ACX3422. Covered by a one year warranty.

Product overview

A battery master switch disconnects the battery from the vehicle's electrical system at a single point, serving three key purposes. For safe servicing, it prevents accidental starts and protects against short circuits when working on the electrics. For storage, it prevents parasitic battery drain during extended periods without use. For anti-theft, the removable key means the battery cannot be reconnected without the key a simple but effective deterrent for parked vehicles and caravans.

At 75A continuous at 12V the ACX3409 is suited to main battery isolation in most passenger vehicles, 4WDs, caravans and light commercial vehicles. The two 8mm stud terminals accept ring terminals with an 8.4mm or larger ID for main battery cable connections. The 24mm mount diameter and 33mm mount length suit panel, firewall and recessed mounting locations. The key is only removable in the Off (open) position, ensuring the circuit cannot be closed once the key has been removed.

Features and benefits

Battery master isolation switch: Single point of disconnect between the battery and vehicle electrical system for safe servicing, storage and anti-theft protection.

75A continuous at 12V: Rated for main battery isolation in passenger vehicles, 4WDs and caravans.

Key removable in Off position only: Battery cannot be reconnected without the key. Simple anti-theft deterrent and safety feature.

Two-position On/Off (SPST): Single pole single throw operation with no intermediate positions.

Two 8mm stud terminals: Main battery cable connections accepting ring terminals with 8.4mm or larger ID.

Panel or recessed mount, 24mm diameter: Compact form factor for dash panels, firewall and recessed mounting locations.

Replacement key available: OEX ACX3422 is the replacement key for this switch.

One year warranty: Covered by a one year OEX warranty.

Technical specs

Goes well with

OEX ACX3422, Replacement Key for ACX3409

Frequently asked questions

What is a battery master switch used for? A battery master switch provides a single point of disconnect between the vehicle's battery and its electrical system. It is used for safe servicing — preventing accidental starts and protecting against short circuits for extended storage to prevent battery drain, and as a basic anti-theft measure by preventing the battery from being reconnected without the key.

Why is the key only removable in the Off position? The key can only be removed when the switch is in the Off (open) position. This ensures that if the key is removed and taken away, the circuit cannot be accidentally or intentionally closed the battery remains isolated until someone with a key returns. This is a deliberate design feature for anti-theft and safety purposes.

What cable termination size suits the 8mm studs? The 8mm stud terminals accept ring terminals with an 8.4mm or larger ID hole. Suitable OEX options include the ACX3056 (8.4mm ID, blue) and ACX3057 (10.5mm ID, blue). Select a ring terminal rated for the cable gauge used in the main battery circuit.

Can this switch be used in a 24V system? The ACX3409 is rated at 75A at 12V. A 24V rating is not confirmed in the current product data. Check the OEX product specifications for 24V suitability before use in a 24V application.

What if I lose my key? A replacement key is available as OEX ACX3422. It is worth keeping a spare key in a secure location separate from the vehicle.