Battery Issues

Originally posted by CharlieM  Either lead is OK though convention is to put it in the positive lead.

I have done low voltage alarm systems for 20+ years and the only way to be certain is to yank the positive lead.  You can still complete a circuit downstream with a screwdriver touching a terminal too close too the edge of a j box and make some sparks.  

I'd probably put the switch on the positive side if I were to install one, just because that's where most people put it and therefore, if the occasion ever arose, that's probably where they'd look for it if they had to.

The NHRA is concerned with spilled gasoline and cutting off engines after wrecks and they require battery cutoffs on the dash where they are easily accessible by rescuers. 

The idea of a wrench or screwdriver shorting things out doesn't apply once a switch is installed, unless you really make an effort to short the circuit.  Once the switch is flipped on the positive or negative side the circuit is open and there are no more electrons to cause sparks.

The fact that electricity flows from the negative side of the battery to the positive kind of argues for switching the negative side -- cutting off the electricity at the source, but they all stop moving no matter where the circuit is opened. 

This is an interesting subject to Google, if you're interested in this kind of thing.  There are strong opinions on both sides of the argument.

TT

Are you positive, or being negative about it?  This subject is very charged.

Originally posted by sailor323 Putting the switch on the positive side is the safer choice.  The reason is simple.  If there is some kind of grounding of the positive wire between the battery and the pod,  there is a significant risk of fire.  Disconnecting the positive side eliminates that risk, while switching the negative side does not.  Switching the negative side leaves the positive wire hot.  A major no-no in electricity.  Essentially, if you put the switch on the negative side, you have not disconnected the battery from the pod.

If the switch is between the negative battery post and the ground, which it pretty much has to be, then there is no danger of spark from a positive wire.  There would be no negative to the ground.  Sparks happen when the circuit is closed from positive to negative (not to ground).

TT