interesting problem

[electricalperson]

today i was measuring voltage of wire inside a box that is in the ground. i had 50 volts on the simpson 260 and 50 volts on the fluke 117 high impedance function. i use the loz function and it went down to .6volts. i clip the test leads of the 260 to the wires and put my wiggy in paralell and voltage goes away. i try to locate other junction boxes and i find one that was buried and completly filled with water splices under water

i trace the wires back and find the one i was measuring voltage too went to a time clock that i was not working on. the wire that had 50 volts went there and wasnt energized by the time clock.

i emptied the water out of the buried box and replaced all the splices with waterproof wirenuts rated for DB. i left the leaves and pine needles off of the top

i energized the circuit and the 50 volts went away. i came to the conclution that the wire was picking up voltage from the 120 volt circuit. all the splices in the hidden junction box were under water so the voltage went through the water.

does this sound correct or could it of been something else i overlooked?

 

[electricalperson]

there was other wires but the one i measured too is the only one. im willing to bet they all were energized

 

[iaov]

Using a 260 usualy dates a guy!!:smile:I always figured you were younger. Anyways its possible the water was acting as a high resistence connection and causing you to see the 50 volts. 480 Sparky had some great pictures a while back demonstrating induced voltage (wich this might have been too). He used a DVM to measure the induced voltage and then put a "Wiggy" across it and made the induced voltage go away. I have several fancy meters but I would never leave home without my Wiggy..

 

[electricalperson]

Using a 260 usualy dates a guy!!:smile:I always figured you were younger. Anyways its possible the water was acting as a high resistence connection and causing you to see the 50 volts. 480 Sparky had some great pictures a while back demonstrating induced voltage (wich this might have been too). He used a DVM to measure the induced voltage and then put a "Wiggy" across it and made the induced voltage go away. I have several fancy meters but I would never leave home without my Wiggy..

im 25 years old and i love analog equipment:grin:

 

[electricalperson]

i figured that was the problem. i like to verify what i think to make sure i know what im talking about and not sounding like an idiot:grin:

 

[gar]

090714-2118 EST

electricalperson:

Pure distilled water has very low conductivity. Exposed to open air and it absorbs CO2 and this increases its conductivity somewhat.

Normal tap water has a substantial amount of dissolved salts. This produces greater conductivity, but still a long ways from that of a copper wire.

Your Simpson 260 is a 5000 ohms/volt unit on AC. This is listed on the face of the dial. On the 50 V AC range the resistance of the meter is 50*5000 = 250,000 ohms, and on the 250 V range it is 5 times greater.

Suppose you read 50 V on the 50 V range, then the leakage resistance in your watered box was about (70/50)*50,000 or 70,000 ohms.

Some references:
http://www.lenntech.com/water-conductivity.htm
http://www.biophysica.com/conductivity.htm
http://scienceathome.cienciaviva.pt/conduti_agua_eng.html not very good
http://www.finishing.com/280/15.shtml
http://www.epa.gov/volunteer/stream/vms59.html

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