Battery Disconnect: Knife-switch for 99 Merc Grand Marquis

[RoboGen]

I purchased a knife-switch type kill-switch made by the Wirth Co., for the battery on my '99 Merc Grand Marquis. The instructions say it should be installed on the NEGATIVE post but, I would like to install an other one on the POSITIVE post as well, because my car's manufacturer states that BOTH + & - posts be disconnected, when servicing electrical components (to insure airbag dis-connectivity / no possibitlty of accidental discharge). It is a bit of a pain in the rump to have to unscrew the batt connector from its post EVERY time I have to service an electirical component-- aside the wear-&-tear it does on the connector & bolt: Is there some reason that I should not install one on the positive-side, too; or should I just use the knife-switch on the " - ", and just disconnect the " + ", when working on electrical components? My biggest concern is that the switch won't be able to take the amperage, if placed on the positive post... but, THAT my just be me showing my ignorance (hence, my request for help! )

[way2old]

You have the same amperage on both posts when the battery is connected and something is turned on. Most of the time, if you are not replacing the PCM and the ignition is off, you do not need to disconnect the battery to replace any electrical componet. The stereo may be an exception because it has memory functions.

[Big Bruce]

I think the reason it says to connect it on the negative side of the battery is to prevent a short if the switch were to contact the body, perhaps while opening or closing it.