Ground Resistance Test

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Flex said:
Yea thats it.
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In that case it would be rare to have less than 750 millivolts without a bonding connection to the electrical system. You would be reading the voltage drop on the utility primary grounded conductor. You would also be reading the voltage drop on the building neutral conductor between the point where you connected your meter lead and the service main bonding jumper.
 
090214-0925 EST

IFlex:

You have not yet adequately defined the test circuit you used, or were supposed to use.

Your last post clears up nothing.

To what is the non-hot terminal of the lamp connected? And the meter is connected between what two points?

.
 
gar said:
090214-0925 EST

IFlex:

You have not yet adequately defined the test circuit you used, or were supposed to use.

Your last post clears up nothing.

To what is the non-hot terminal of the lamp connected? And the meter is connected between what two points?

.
Click to expand...

Sorry for delay in responses my computer keeps crashing. The meter goes to the non-hot terminal and the ground rod. Ill try to dig up the paperwork for the test and scan it on here.
 
Flex said:
Thats what I thought or else there would have to be 15 ground rods driven.
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An increase in the number of rods will have no effect unless you happen to start installing them close to one or more of the service grounding electrodes. Even in that case you may not get below 3/4 of a volt.
 
090214-1440 EST

Flex:

If you connect a 120 V 100 W lamp ( 144 ohms at 120 V across the lamp, 10 ohms if near zero V across the lamp) in series with a voltmeter set on a range above 120 V, and these two items are connected between a 120 V hot conductor and the isolated ground rod, then the meter will read very close to the line voltage.

A Simpson 260 meter on the 250 V range has an input resistance of 250 V * 20,000 ohms/volt = 5,000,000 ohms. The lamp will not glow and be near 10 ohms, even if the ground path resistance was 1000 ohms the error in the voltmeter reading relative to the line voltage would be about 1 part in 5000, not readable on this meter.

I do not believe this is the circuit because it would serve no useful purpose.

I really believe the intended circuit is as I described in an earlier post. The light bulb is connected between the 120 V hot wire and the isolated ground rod. This is to serve as a means to inject a reasonable, but low level current into the isolated ground path circuit. 0.83 A as I previously indicated.

.
 
gar said:
090214-1440 EST

Flex:

If you connect a 120 V 100 W lamp ( 144 ohms at 120 V across the lamp, 10 ohms if near zero V across the lamp) in series with a voltmeter set on a range above 120 V, and these two items are connected between a 120 V hot conductor and the isolated ground rod, then the meter will read very close to the line voltage.

A Simpson 260 meter on the 250 V range has an input resistance of 250 V * 20,000 ohms/volt = 5,000,000 ohms. The lamp will not glow and be near 10 ohms, even if the ground path resistance was 1000 ohms the error in the voltmeter reading relative to the line voltage would be about 1 part in 5000, not readable on this meter.

I do not believe this is the circuit because it would serve no useful purpose.

I really believe the intended circuit is as I described in an earlier post. The light bulb is connected between the 120 V hot wire and the isolated ground rod. This is to serve as a means to inject a reasonable, but low level current into the isolated ground path circuit. 0.83 A as I previously indicated.

.
Click to expand...
Im still lookin for the paper.
 
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