Master On/Off Switch
Brand: Blue Sea Systems
Product Description:
- Single circuit on/off switch
- Continuous rating: 300A
- Voltage range: 12-48V
- Colors: Red or black
Purpose:
- Disconnects batteries when performing routine maintenance
- Turns off electrical system for long-term storage
Frequently Bought Together
Below are the most commonly used components when installing this master switch.
- 2/0 AWG Wire – This wire connects the switch to the batteries and to the bus bars. Learn more about this wire.
- 3/8″ Copper Lug – Crimps onto the 2/0 AWG wire and attaches to the switch.
- Bus Bar – The switch connects to this bus bar so that power is distributed to downstream electrical devices. Learn more about bus bars.
- 300A ANL Fuse – The switch connects to the 300A fuse to protect the electrical system.
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Where To Install The Master Switch
This master on/off switch is installed between the 300A fuse and the positive bus bar (red). To make the connection, use 2/0 AWG wire and 3/8″ copper lug terminals. Refer to the wiring diagram below to visualize where the switch is installed.

Need More Wiring Information? Download our Electrical Wiring eBook.
Technical Details
Switch Positions | 2 |
Current Rating | 900A Cranking (30 sec)/ 500A Intermittent (5 min)/ 300A Continuous |
Max Voltage | 48V DC |
Terminal Stud Diameter | 3/8" (M10) |
Standards Met | IP66 waterproof, ISO 8846 and meets ABYC requirements. |