International Association of Certified Home Inspectors
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| Electrical Contains discussions about electrical systems. This includes outlets, panels, wiring, et cetera. |
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#1
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120V circuit to detached garage in conduit from load side panel in house.
My 61-165 indicated an open ground (and a correct ground everywhere else I tested inside the house), when further investigation by others indicated a correct ground I went back and retested with my 61-058, which indicated a correct ground. Defective 165, or ???? |
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#2
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The 61-165 is more "sensitive" than others. Many times it will show an "open-ground" condition, when the contact/connection is poor.
Next time, check the ground impedance when you get this reading. IF YOUR INSPECTOR IS NOT USING THERMAL IMAGING, YOU'RE NOT GETTING THE WHOLE PICTURE ℠ Jeff PopeJPI Home Inspection Service Santa Clarita CA (661) 212-0738 Santa Clarita Home Inspection http://www.MyInspector.net |
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#3
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If you are not sure about a circuit being open ground, you can plug in your tester, then use a voltage indicator on the face plate screw to see if it lights up.
Like this:
"An expert is a person who has made all the mistakes that can be made in a very narrow field" Niels Bohr "Learn all you can from the mistakes of others. You won't have time to make them all yourself" Alfred Sheinwold Eureka, Fortuna & Arcata, CA
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#4
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OK, bear with me a bit, I clearly don't understand this as well as I should, and if I don't probably a lot of others don't either.
Jeffery, Across what two points should I measure the impedance, and what should I expect to find? Ralph, What result should I expect from your test technique? Thanks |
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#5
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Quote:
You should have one of these indictors to test for reverse polarity on open ground and 2-prong receptacles (the smaller slot should be hot, and the other one is not) I recommend the fluke indicator. The CG el-cheapo's are next to worthless IMHO. "An expert is a person who has made all the mistakes that can be made in a very narrow field" Niels Bohr "Learn all you can from the mistakes of others. You won't have time to make them all yourself" Alfred Sheinwold Eureka, Fortuna & Arcata, CA
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#6
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Quote:
Paul W. Abernathy,CMI,CEI,CEPE NECŪ Consultant/Columnist www.twitter.com/ElectricalGuru - ICC & IAEI Certified Electrical Inspector - ICC & IAEI Certified Electrical Plans Examiner - Look for my article in the Nov/Dec 2009 IAEI Magazine - 2007 "Top Gun" Winner - Mike Holt Enterprises " visit www.TheElectricalGuru.com Today !" |
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#7
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Quote:
A "normal" reading is generally in the range of 0.25 ohms. A reading of 1.0 or greater is too high for the EGC, and may show as an "open-ground" on the initial test cycle of the SureTest. FWIW - If you test the ground impedance on a circuit that is GFCI protected, the GFCI will (should) trip. IF YOUR INSPECTOR IS NOT USING THERMAL IMAGING, YOU'RE NOT GETTING THE WHOLE PICTURE ℠ Jeff PopeJPI Home Inspection Service Santa Clarita CA (661) 212-0738 Santa Clarita Home Inspection http://www.MyInspector.net |
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#8
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Jeff/Paul, wasn't there a discussion a couple of years ago about a false open ground with an outlet, typically in the garage, that is directly out of the panel box, or am I making this up?
Dave Bush, CMI Quality Home Inspections "Always do what's right, not what's popular" |
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#9
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I don't recall that particular discussion Dave, however, there have been several discussions regarding "false-ground" readings with the SureTest.
Basically, the SureTest gives this indication when the resistance is to low between the ground (egc) and the neutral (grounded conductor). It's common to get this indication when the receptacle is close to the service equipment (where the grounds and neutrals are bonded) or near a distribution panel where the neutrals have been grounded (which we know to be improper). The indicator is intended to help the inspector identify "bootleg" grounds, where the egc has been "grounded" to the circuit-neutral, rather than grounded at the panel. IF YOUR INSPECTOR IS NOT USING THERMAL IMAGING, YOU'RE NOT GETTING THE WHOLE PICTURE ℠ Jeff PopeJPI Home Inspection Service Santa Clarita CA (661) 212-0738 Santa Clarita Home Inspection http://www.MyInspector.net Last edited by jpope; 9/24/09 at 9:18 PM.. |
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#10
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Probably loose conduit at a fitting or corrosion at a fitting. Cuz you know EMT is perfect...Right Paul
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#11
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lol....Gotta love those Chicago EMT Lovers....lol
Paul W. Abernathy,CMI,CEI,CEPE NECŪ Consultant/Columnist www.twitter.com/ElectricalGuru - ICC & IAEI Certified Electrical Inspector - ICC & IAEI Certified Electrical Plans Examiner - Look for my article in the Nov/Dec 2009 IAEI Magazine - 2007 "Top Gun" Winner - Mike Holt Enterprises " visit www.TheElectricalGuru.com Today !" |
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#12
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Thanks for the information.
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#13
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It belongs in metal conduit the way G-D intended.
Romex is glorified extension cord.(I am sure Edison and Tesla would agree ,if they had not both died touching Romex). |
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