Batt. cutoff switch

[LBC286@aol.com]

A question came up on the Spridgets list about which line to use 
when installing a battery cutoff switch in a car.  The concensus is 
to install it in the line that goes to the chassis...that is, the neg. 
cable on a neg. ground car or the pos. cable on a pos. ground car.  
But, no one can explain why.

Can anyone here take a shot at the reason?  Or give me any other 
info about batt. cutoff switches?

TIA,

Allen Hefner
Philly Region SCCA Rally Steward
'77 MG Midget
'92 Mitsubishi Expo LRV Sport