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#71921 - 11/10/06 01:50 PM Circuit tester
Taylor Offline
Junior Member
Registered: 11/10/06
Posts: 2
Loc: Salem, Oregon, USA
Does anyone know how sensitive those little three prong circuit testers are? We were using them to confirm ground in the 110 outlets in our plant, but recently discovered that they can be misleading. One of them registered a gound ok but the ground measured 1700 ohms. We are now, of course, going around with a proper VOM rechecking all receptacles.
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#71922 - 11/10/06 03:44 PM Re: Circuit tester
Zapped Offline
Member
Registered: 10/01/02
Posts: 482
Loc: Huntington Beach, CA, USA
IMHO, I wouldn't use one of the cheapo ones for anything commercial at all.
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#71923 - 11/10/06 06:14 PM Re: Circuit tester
NJwirenut Offline
Member
Registered: 09/15/01
Posts: 806
Loc: Bergen County, NJ
Those testers use neon bulbs, which can light on a milliamp or less of current flow. They tell you only that there is some kind of path to ground, not that it is a GOOD path.
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#71924 - 11/13/06 01:52 PM Re: Circuit tester
Taylor Offline
Junior Member
Registered: 11/10/06
Posts: 2
Loc: Salem, Oregon, USA
Thanks guys. We are no longer using these things in the plant. I never really thought much of them anyway, but we were sucked in by OSHA. There field agents use these same chepo gadgets to check for grounds during their investigations.
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#71925 - 11/13/06 03:39 PM Re: Circuit tester
RODALCO Offline
Member
Registered: 12/08/05
Posts: 854
Loc: Titirangi, Akld, New Zealand
In New Zealand we use the AVO-Megger LT 310 Loop Impedance Tester on the 230 volts MEN system.
The best way to test is to use a loop impedance tester instead of relying on neons which can give you false readings.
This one imposes a test current between the phase and neutral and earth.
It will tell you in Ohms and kiloAmps what fault level is available.
it will also confirm that the polarity is correct.
_________________________
The product of rotation, excitation and flux produces electricty.
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#71926 - 11/13/06 04:01 PM Re: Circuit tester
scameron81 Offline
Member
Registered: 02/24/04
Posts: 75
Loc: Healdsburg, ca, USA
Check out this interesting link regarding OSHA and their cheapo testers.

http://www.osha.gov/pls/oshaweb/owadisp.show_document?p_table=INTERPRETATIONS&p_id=21410
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