Odd Suretest reading

[apfaff]

Ok, here is a weird one. I just had my newest sure tester show a lack of ground on a GFCI circuit today. Every outlet in the garage and exterior on this circuit lacked an equipment ground but still tripped with the meter. Then I tried my backup 3 bulb and it showed it as OK and grounded. Odd… then the interior GFCI’s all checked normal. Went back out to check again and still…open ground on that circuit. Took off the cover plate and saw the ground and even checked it with the multimeter. All OK.

Anyone else ever had this happen? I can’t seem to find a reason for it and have tested many GFCI’s since without incidence.

If it was a fluke with the tester I would have thought it would not repeat itself on the garage GFCI and on the other protected outlets in that circuit.

[Stephen W. Stanczyk]

Did you wait at least 30 seconds between tests?

[apfaff]

yes, and got consistent results.

[Bruce M. Graham]

how close to the panel was the outlet? Close proximity to the panel can cause this kind of reading.

[jking2]

I had similar situation in my own home some years ago. It turned out that the wide slot and the ground connection were both hot, and the narrow slot was connected to neutral. Apparently a nail had shorted the hot lead to ground in the wall, and someone solved (concealed) the problem by switching the wires around, creating an extreme electrocution hazard.

Jim King

[Jeffrey R. Pope]

Originally Posted by apfaff

Anyone else ever had this happen? I can’t seem to find a reason for it and have tested many GFCI’s since without incidence.

Quite often actually. This is because the SureTest is very "sensitive." If the ground plug at the receptacle is worn, the SureTest will indicate an "open-ground."

Your cable should be changed out every couple of months to ensure good connections to the receptacle. If your cable is relatively new, it's likely that the receptacles are/were somewhat worn (old).

Any time you get an "open" - (ground, hot or neutral) reading with your SureTest, it should be verified with another tester. You should also make sure you cable is relatively new if you are reporting on "voltage-drop," as a worn cable will give readings that are misleading.

[apfaff]

Originally Posted by jpope

Quite often actually. This is because the SureTest is very "sensitive." If the ground plug at the receptacle is worn, the SureTest will indicate an "open-ground."

Your cable should be changed out every couple of months to ensure good connections to the receptacle. If your cable is relatively new, it's likely that the receptacles are/were somewhat worn (old).

Any time you get an "open" - (ground, hot or neutral) reading with your SureTest, it should be verified with another tester. You should also make sure you cable is relatively new if you are reporting on "voltage-drop," as a worn cable will give readings that are misleading.

Hi Jeff,
Yes good advice and I also do this when I get unusual results. I didn’t think it was a worn outlet or bad connection at the tester because with this one every outlet on that circuit showed open ground. And I didn’t think the tester would trip it without a ground connection. I run into many open grounds on two wire systems that use GFCI and have to trip using the receptacle test button. The Suretest shouldn’t have tripped the circuit if there wasn’t a ground connection yet it did. False ground was not and issue here either. I now have two Suretesters I guess I need to carry all of them!

[apfaff]

Originally Posted by bgraham

how close to the panel was the outlet? Close proximity to the panel can cause this kind of reading.

Over 100 feet of wire at least. I am aware of the false ground possiblity in that situation.

[David A. Andersen]

Over 100 feet of wire at least.

That is way too long. Did you have a major voltage drop?

[Jeffrey R. Pope]

Originally Posted by apfaff

And I didn’t think the tester would trip it without a ground connection.

There was a connection, it just wasn't strong enough for the SureTest to register it.

The reading is actually accurate. It's indicating a diminished grounding connection.

Try scrolling through your menu next time this happens. If a true "no-ground" condition exists, only the line voltage and voltage drop measurements are available.

If it's a weak or diminished ground, all menu options are still available. You can also verify this through the "impedance" menu. However, if you are on a GFCI protected circuit, checking ground impedance will trip the device if there is a grounding connection.