False Ground

[Jeffrey R. Pope]

Originally Posted by brian winkle

The suretest uses a resistance measurement to reveal a bootleg ground, won't it lie on a receptacle located very close to the panel?

As with any instrument, learning to interpret the readings is an important factor. The SureTest will give a "false ground" indication" when the resistance between the grounded conductor and the grounding conductor is too low. This may occur at close proximity to the service equipment or where a bootleg ground is present.

Is it lying? No, it's simply giving a reading. It's up to the HI to try and determine if the reading is actually a problem. If it is questionable, it should be deferred.

[Paul W. Abernathy]

Great stuff by Jeff....Lets BUMP this puppy

[brian winkle]

I guess I would have to disagree with you there Jeff, if the instrument displays a false ground reading in close proximity to the panel when there is no false ground present, I would call that lying

What about the HI who reports it as a false ground and causes additional expense of an electrician when one was not needed?

[William J. Decker]

How about the HI that does not call it out and does not have a licensed and insured electrician evaluate it (and assume the liability) and gets wacked?

HIs are like general practicioners. Electricians are specialists.

[Richard L. Bennett]

Remember we are only dealing with three conductors here


A lot different than checking computer network cabling that is wired by the same "professional"

PULL THE COVER OFF AND LOOK AT IT

You pulled the cover off the electrical panel didn't you?? What is a little piece of plastic and one screw?




rlb

[Bruce A. King]

Consider a case where some of the receptacles are switched from a 3 or 4 gang wall switch box with more than one hot feed to the box. You have 3-wire plus ground cables present, different neutral circuits etc.

It is not just simply 3 wires sometimes, if you do not remove the outlet and look at the splices that may be behind it you could miss a lot.

If you are going to remove cover plates you should remember that you are still only seeing a small portion of the picture. House can have many junction boxes and splices.

Another note:
Installing an AFCI on a circuit that operates and tests ok can be a learning experience when it trips due to a shared neutral somewhere.

[Richard L. Bennett]

Bruce

Point well taken

What seems to be basic knowledge to many is advanced to many others.

It is hard to inspect something that one does not understand. Too bad homes are not required to have on file up to date one line electrical diagrams

rlb

[Jeffrey R. Pope]

Originally Posted by rbennett

PULL THE COVER OFF AND LOOK AT IT

As Bruce stated, that may not give you the answer you're looking for. As in the case where the homeowner creates the "bootleg" at an attic junction box rather than the receptacle itself - which is quite often the case in older, two-wire systems, where NM is tied in for additional circuits.

We need to learn to interpret our instruments based on their indicators as well as other conditions present in the home.

[Richard L. Bennett]

Jeff

Understand about the J box in the attic "converting" two wire to three wire. Wonder how far away the box could be so that the suretest would not see it?

rlb

[Jeffrey R. Pope]

As a general rule, the SureTest will indicate a "false ground" if there is a connection between the neutral and ground within about 15 feet (conductor length) of the receptacle being tested.

Obviously, there are many variables that can come into play, so it's important to "get a feel" for your tester before writing up every false-ground indication.

It becomes more apparent in cases such as condos, where they have interior distribution (sub) panels, as these require isolated neutrals. A false ground indication in this case would almost certainly indicate a wiring error, whether it's a bootleg ground, or neutrals bonded/grounded to the distribution panel.

In any event, we shouldn't arbitrarily "flag" every false-ground indication.

[rdawes]

Side note on Sure Test instruments. I bought a 61-155 off of Ebay about a year ago and used it on every inspection since then. About 3 weeks ago the % Voltage Drop measurement stopped working. I sent it in to Sure Test to ask what it would cost for repair. Today I got a brand new 61-165 back from them for free! That is good customer service!