3-Prong vs. Idea Analyzer

Have any of you ever seen this…

I was inspecting a condo the other day and found the following at an AFCI protected receptacle in a bedroom…

*3-prong tester indicated correct polarity and ground
*Idea analyzer indicated correct polarity with no ground (not a false ground)
*Idea analyzer successfully tripped the AFCI

Any idea what’s going on?

If the 3-light tester has a dim ground indication that is a fault condition (high resistance). This may not be noticeable unless you are tuned into looking for it.

The other tester probably indicates “no ground” if the ground resistance is above a certain level.

When is the last time you “tested” the “tester”?

I only use 3-prongs as a quick check to see if power is present, and when testing gfci/afci as a visual on multiple receps. Don’t trust them for anything else. Seems like I had to replace them all the time. Stick with the analyzer.


That’s your answer. The SureTest is much more sensitive and much more accurate than the three-light tester.

A grounding connection is not needed for the AFCI testing feature to perform its function and trip the breaker.