Re: Grounded circuit troubleshooting

AC OR DC???????

Lawrence_Glickman wrote: 
On 30 Oct 2005 22:48:19 GMT, ag384@xxxxxxxxxxxxxxxxxxx (William R.
Watt) wrote:


A test light can be used. It's simpler and cheaper, just a light bulb with
two wires comming from it. Touch the wires to two pices of metal and if a
current is flowing it will illuminate the bulb.


If there is a voltage differential between the two pieces of metal
touched with the probe wires, then a voltage differential will be
displayed. Example:
1 wire is at 100 volts
the other wire is at 300 volts

what do you think you will read between these wires if these wires are
in an open circuit?

The answer is:

between eachother, 200 volts
between100 volts and earth ground or neutral safety bus, 100 volts
between 300 volts and earth ground or neutral safety bus, 300 volts

This has nothing at all to do with current.  There can be zero current
flowing in the wires, and you will still measure this voltage.

Amperes is the unit of measurement for current.

What if -both- wires are alive with 300 volts?  What will you read?

ZERO VOLTS if you just put your probes on the two wires, each carrying
300 volts!

IOW, if you don't know what you're doing, DON'T DO IT.

Lg



"dontlookback" (dmemail@xxxxxxxxxx) writes:

I have a 71 Opel GT with a dead short in the instrument panel lunination
circuit.  What is the best way to isolate the ground as it seems that
everything is tied together into one big mess.  Are there any free
internet sites that explain basic ammeter use and trouble shooting of
grounded circuits.  My experiance with meter use is none and would like to
learn more in this area.

Thanks



.

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