Outlets tested as semi-grounded with odd N-G and H-N voltages

[Frank L. Bartlo]

I found several outlets in one room that tested as almost having an open ground (LED on right faintly lit up -- see pic), in a house with grounded wiring, and other outlets tested as properly grounded. The VOM, read 119V from H-N (OK), but only 23V from H to G, and 11V from H-N.

So the outlet appeared to be working for 2-prong purposes just fine, but appeared to be weakly grounded. I did a search and couldn't find any threads on this sort of thing.

First explanation that comes to mind is a poor grounding connection in the circuit, with excessive resistance. The room did appear to have been converted from 2 rooms to one big room, so amateur wiring appeared likely, with probably junctions in light fixture and/or switch enclosures. What's going on here?

[Bruce A. King]

It takes a really good electrician to figure out the unusual symptoms.
It can be any combination of bad connections, improper bonding, current on ground conductors and even problems in a neighbors house backfeeding current through public water pipes.

[Frank L. Bartlo]

I'm thinking a bad connection because other outlets in the house and even the room tested as operating properly. Certainly is an unusual observation, more the sort of thing I'd expect in an older house with substandard grounding via old metal-jacketed ("BX") cable not done properly.

[Robert Meier]

Originally Posted by fbartlo

I found several outlets in one room that tested as almost having an open ground (LED on right faintly lit up -- see pic), in a house with grounded wiring, and other outlets tested as properly grounded. The VOM, read 119V from H-N (OK), but only 23V from H to G, and 11V from H-N.

Can you explain this?

[Jeffrey R. Pope]

I always report ineffective grounding when the resistance exceeds 1 ohm. I don't really care what the cause is.

Like Robert, I don't understand your voltage readings.

[Christopher Mennella]

Have you ruled out a faulty tester?
I carry two of these plus a SureTest just for redundancy.

[Roy D. Cooke, Sr]

Sounds like there could be some damp areas some where or it Carbon build up, dirt ect.
These cheap testers read strange things they draw so little current .they can give a voltage reading from my left hand to my right hand..... Roy
I would need to be there to figure out what is happening

[Michael R. Boyett]

If you look at the internal wiring diagram (3 neon bulbs w/ 47k resistors) of a 3-light tester then the most likely scenario is a poor, high resistance Grounding connection somewhere in that branch circuit as has been stated. I suspect the 11V was really G-N and was a typo.

[Jeffrey R. Wicklander]

Chances are your digital voltmeter uses high impedance which may be why you're picking up small voltage readings (due to inductance). Also, as previously mentioned, there may be something adding excess resistance on the ground. It may be a bad connection or an extra long run of BX, where the shell is being used as the equip grnding condctr.

Jeff