Main Battery Switch

[WetRaider]

Question here ... before I cause sparks ...

Bought a Blue Sea Systems main battery disconnect switch.  Simple on-off operation for a single battery application. 

Here's a picture of the back.  Two terminals.  One marked "BATTERY," the other marked "COMMON."

You'd think it would be straight forward, but my mind is working like this ... those terminals are solid studs.  With a lock washer and nut in place, what's to keep the switch from working?  Does the "COMMON" designation actually mean 12v out to motor?  I imagined it would work like a light switch, the ground (common) wires are straight from motor/ignition to battery, the positive 12v goes into the switch at one terminal & out to motor & ignition at the other. 

Anybody else wired one up with positive on the battery terminal and ground on the common terminal?  I just can't wrap my head around it - it defeats the switch.

[Rich_V174SS]

You connect a red battery cable from the positive terminal of the battery to the switch terminal marked BATTERY, then you connect all other red/positive wires from your engine and accessories to the COMMON terminal, except if you have an auto bilge switch which you connect to the battery side of the switch so it always remains active. You do not connect any negative or ground wires to the battery switch. In effect what you're doing is installing the switch in-line with the positive wire to the battery and all it does is make or break connection.

[WetRaider]

That's exactly the way I thought it should be ...

but the "COMMON" terminology threw me.  I've never referred to ground wires as common, but I know that many do.  I couldn't imagine using the switch any other way than you described - but I didn't want to short a battery or anything like that.  Ok, moving forward ...

[Rich_V174SS]

I also use a master On/Off switch for the battery, one from Perko.