Bobbie, The term ground is used to mean two things
1) In a car's DC system "ground" means the path to get to one of the battery poles (usually negative) through the body of the car. This ground does not need to be connected to the earth; in fact it will only be connected if you have one of those conductive " tails" that links the body of the car/truck to the surface of the road. This type of ground carries current all the time and is connected to one terminal of each light bulb, motor, etc.. In a nutshell, ths type of ground is to save you from reducing by one the number of wires that go to each place in the car. 2) In a house's AC system there is a ground/earth wire that is not connected to any of the two terminals of a given light bulb; it is connected to the body/chassis of all appliances, motors, etc, and some metal pipes but not to the terminals that carry current into them. This sort of " ground" will only carry current if there is a leak between one of the two AC wires and anything connected to the ground system. In a nutshell, this type of ground is to save you from electrical shock if one fo the two AC wires touches the body of your washing machine and you touch the washing machine. Cars normally do not have a #2 ground system, ie connection to earth. Given that a car only has 12 volts the only reason for that would be to get protection from sparks arising form static electricity (eg when you get the gas fillup nozzle close to the car fill-up hole, or to save you from having your hair look funny when driving in a hot dry day). In some places with very dry climates folks hang form their cars a metalic piece that touches the ground from time to time an din teh process brings the "potential" (voltage) of the car body in line with the earth. Big boats tend to have a type 2 ground system, which is usually called bonding, for both the same reason as in a house plus but also to protect from stary currents. This is very difficult to understand (at least to me) because tehre are a couple of different ways to get teh same result, and different countries tend to do things differently... I hope this helps. Carlos On 7/6/06, Bobbie Mayer <[EMAIL PROTECTED]> wrote:
That's what we would need- a wire from the grounding wire to the wooden bar. At this point I've temporarily given up and will use hand signals for the couple of miles we need to drive in the daylight. Then tomorrow we'll look for a piece of wire to splice in. However, I don't get it- cars aren't really grounded; how do they work as a ground? Is it just that the size of the car and trailer combined is enough? I never really thought about that before. Bobbie _______________________________________________ http://mailman.xmission.com/cgi-bin/mailman/listinfo/montgomery_boats
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