I
have a 1960 PD4104 GMC bus. It has been
converted to a motor home. The issue
that I am dealing with is polarity. Most
vehicles today have negative grounds.
What this means is that the negative post of the vehicles battery is
connected to the frame of the vehicle and the positive post is connected to all
the components. If you take a wire that
is connected to the positive side of the battery and touch the frame, you get a
short. This is not good. When this happens there can be sparks, melted
wires and sometimes even fires.
Back
before the 1960’s some vehicles used positive grounds. Again, this time the positive post was
connected to the frame and the negative post to all of the components. Electricity does not care which direction it
travels. All it needs is a complete
circuit or circle to function. Positive
ground vehicles worked just fine.
Sometime in the 1960’s someone made a regulation or a law or something
and all vehicles after that date were negative grounds. Nowadays I suppose that a component could be
polarity sensitive. I have heard that a
motor may run in different directions depending on the polarity. But I don’t know for sure.
So
here’s the problem. My bus is positive
ground and the generator is negative ground.
What happens if I bolt the generator to the frame of the bus? Am I going to have a short circuit? I did not know the answer. I was thinking
that grounding two systems with different polarities to the same medium would
cause me problems. I called the
generator maker and asked the question.
Naturally the maker wanted me to talk to a dealer and referred me to
one. I called and asked the
question. The dealer did not know the
answer. I guess part of the problem is
that there have not been very many positive ground vehicles in the universe for
a long time and everyone who dealt with the problem is retired or dead and no
one knows for sure.
Undeterred
I turned to my bulletin board service for the answer. The first person to respond to my post said
it was possible. The second said it was
not. There was a lot of back and forth
between both camps. I still do not know
the answer for sure. I guess I will just
install the generator and see if the bus burns down. I’ll let you know.
