According to an electrical text the following 'explanation is offered:
"The choice of having the + source tied to ground is not arbitrary but
chemistry. Metal is a positive ion and that is why metal corrodes. Make the
metal negative and it does not rust away. To preserve the metal wires and
connectors in systems, they are typically operated negative relative to
ground. Another problem that occures is a surface oxidation in connectors when
no current is flowing. That is why some circuits have a "sealing" current even
though the application does not require any current. "
Also DC current flows from the negative terminal to the positive terminal. So
using the negative as a ground the car body and wires to a switch are
"technicality" negative charged even though they are not directly connected to
the positive pole. This would in theroy help slow rusting rather than promote
it.
Biff Jones
'59 Bugeye 'Kermit'
'61 AH Sprite 'Ole Gray' in the "Healey Book"
'71 Midget 'Freebie"
http://sprites2.homestead.com/
|