1-2-Both switch for single bank distribution

[dissent]

I'm getting ready to wire up my updated house bank and clean some things up. Currently there's no off switch for the house bank which is not great. Start battery system is separate.

Wondering if anyone has used a heavy duty (500a cont., 700 int.) 1-2-both switch to distribute power outbound from the house bank.

The idea being that I can cut the house bank entirely, or just cut power to the DC bus or inverter separately for maintenance.

So basically it would be like below:

Battery bank + bus bar (MRBF fused at each battery +)
                  |
      three way switch ("output") 
      |                         |
Switch "input 1"            Switch "input" 2
      | 150A fuse               | 400a fuse
    DC Bus                      Inverter

Normal ops would be in 1+2 mode, but I could work on the DC system without disabling the inverter by switching to 2, for example.

Is this ungood?

[JoeRobertJr]

Electrically, that should work as you intend. However, since is it contrary to the standard use of that switch, I highly recommend putting a clear label on the switch to clarify what it does. That will help avoid confusion and potential problems for another person looking at your system.

I would lean away from that myself, just making or breaking the appropriate connections when you want to work on one side. Just seems simpler and safer to me, but I do appreciate the convenience of having that switch in there temporarily while overhauling your electrical system, for example.

[SailingHarmonie]

The key aspect of any battery switch to me is the “OFF” position. This is an important safety tool in the event of an electrical fire onboard since it allows you to disconnect the power source from everything. What you do with the other positions, is just a choice.

If it was my boat, there would be separate switches for separate circuits.

[Wotname]

As already stated, electrically it will work but in use, it is likely to be confusing for anyone else except you.

I too would use two seperate ON/OFF switches, one for the bus and one for the inverter. Your boat, your rules!

[Oceanride007]

I have 3 of em 1,2,both,off switches, thats the way it was, But my switches are 30yo now, problem 1, there is a high voltage drop on the charging switch, at 40 amps it would be .5 Volt.

Not sure I like the idea of stitching these slider switches when carrying high power.

Problem 2 is that I use one to switch my starter motor, it also carrys alternator current, its a risk to the diodes when engine running each time I use it.

[dissent]

Hey thanks for the feedback all. Helpful as always to discuss with this crowd.

I guess this falls under the realm of not doing non-standard stuff when it comes to life safety systems. Standard on/off switch is plenty for managing maintenance situations and clearly better for emergencies in the dark or people who aren't familiar with the system.

Now to decide whether to splurge on a new inverter and go 24v or stick with the existing...

Cheers.