PDA

View Full Version : Battery Disconnect


Joe Johnston
06-27-2016, 11:14 AM
+ or - ?? On a 12V negative ground system, which is the preferred terminal to install a battery disconnect switch and why? I have 2 cars, both with disconnects, and one is on the + and the other car the - terminal. Both work with no problems for many years, but is one terminal preferred over the other? Thanks in advance. J

scumdog
06-27-2016, 02:38 PM
+ or - ?? On a 12V negative ground system, which is the preferred terminal to install a battery disconnect switch and why? I have 2 cars, both with disconnects, and one is on the + and the other car the - terminal. Both work with no problems for many years, but is one terminal preferred over the other? Thanks in advance. J

I have the switch on the - post on my Tbird, I figure disconnect that post means that if anything metal touches the + post it would cause no problem unless it also touches the - post.....or something like that!

simplyconnected
06-27-2016, 03:19 PM
A complete electrical path requires TWO wires. Disconnect either and all flow stops.

Which one needs to be disconnected is purely personal preferences and it makes no difference since the only power source is the battery.

This choice is demonstrated in your power window circuits where the circuit breaker interrupts the motor's neg wire.

House wiring always switches the hot lead because all the plumbing is bonded to earth ground and the neutral wire. So in that case, if the neutral were switched, you may pick it up from different sources (like standing in water) which presents a shock hazard. Not so in a car. - Dave

Joe Johnston
06-27-2016, 08:29 PM
Thanks for the replies. I could see no real advantage one way or the other, except for convenience or space limitations.