It TRICKED my plug tester!! Knob and Tube

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Arrggh!! is all i can say, . Im helping out my buddy and he has an old house/duplex that has knob and tube, so naturally I would assume there is no ground.

There are 2 prong recepticles and then i saw 3 prong recepticles. It look like some new work was done. I used my plug tester on it and showed it WIRED CORRECTLY!!.

i continue to check out the place, i find one 3 prong recepticle that needs to be replaced, its smashed. Well i opened it up and low and behold. They (previous homeowners i assumed) took a jumper from the ground terminal of the recepticle and connected it to the neutral of the recepticle.:(

since i saw this, I figured Oh noo, they probably did this to the other ones as well, and yes there were 3 others!! I had to put in 2 prongs in place of the 3 prongs. I did give them 1 gfci (no equipment ) so they can have just one 3 prong.

The point is , it FOOLED my plug tester, didnt think of that. I just HAPPEN TO catch it cause one recepticle was smashed!! Just keep an eye out for "homeowner jackleg" LOL.

Some of them just dont understand that the neutral and ground are to be SEPERATED when NOT at the service, it was like this for years im sure, but i just could NOT leave it like this!! I just had to help my buddy, He bought this place about 2 years ago. Just keep an eye out for this. Your plug tester can show it wired right, when in fact it is WRONG. :)
 
jeff43222 said:
I think Ideal makes a tester that detects bootleg grounds. It's pricier than the standard "idiot light" one I use, but it supposedly works.


I was just getting ready to asked that question. If anyone knew of a tester that could tell of a 'false' ground. would you happen to have a link to that tester??

Im curious as to how does it work? Seeing how the ground and neutral are connected at the panel.
 

ramdiesel3500

Senior Member
Location
Bloomington IN
Here's an interesting thought. Somebody wants to add a recept in a room that is fed with a 2-wire circuit (no ground). They fish a new 12/2 w/g cable into one of the existing old outlet boxes and run it to the new one. Then they connect the grounded and grounding conductors of the new cable to the grounded conductor of the old circuit cable. The new receptacle will test "good" and there is no evidence to the contrary within that new outlet box. I bet this very scenario exist in thousands of old homes right this minute. What do you do???
 
I've seen a lot of this over the years re-wiring old Victorian home in the Northeast. A real quick way to tell if the neutral and grounding wires are tied together in receptacles throughout the home is to pull a neutral off a feeder circuit breaker ( under a no load situation ) and if you see an arc to your grounding system wire, you have this unsafe condition.
True you will have some bleed over but not a clear arcing action. I've actually witnessed the neutrals being nailed to a metal box serving both functions. Dangerous to anyone even to the next electrician coming along behind you. Leave notes in the service entrance panel when the customer refuses correct repair so the next electrician will be wise.
 

hillbilly

Senior Member
Michael.. As I also work on a lot of older homes, and I'm really interested in your post. Can you be a little more clear as to the procedure you use? For example "pull a neutral off a feeder circuit breaker". Do you mean to locate the neutral for a particular breaker and disconnect it from the ground bar? Another.."If you see an arc to your grounding system wire, you have this unsafe condition". Explain that a little more if you will. An arc from where to where, when will it occur and in which box?
steve
 
Trip any feeder circuit breaker or back a fuse out of a board panel ( like your 60 Amp systems common to knob & tube) insulate yourself from a ground path ( gloves or stand on a matt or both if your afraid of a small bite) remove the neutral wire from the DEAD circuit and touch it to a known
earth GROUND. If it ARCS you have a current potential in a wire assumed dead because it is mechanically and electrically joined as a current carrying conductor somewhere else in the house system. What you are experiencing is the return path of a live circuit somewhere else in the house because the neutrals are all tied together acting as both current carrying and ground. Do it again and see if the intensity of the ARC changes. You could have discharged capacitance on a small appliance start winding. If it arcs again and again consistently you should considered finding the fault. You have a potiential for fire in the home.
If you are into old houses you owe yourself a copy of Practical Electrical Wiring by Herbert P Richter, 13th Edition where chapter 22 talks about Old Work; Moderization where he explains NEC and check out the latest edition for Code changes. You have a right to troubleshoot just don't get hurt. Safety first, of course, you can use a meter for the above testing but I'm from the old school physical phenomenon light me up!
 

LarryFine

Master Electrician Electric Contractor Richmond VA
Location
Henrico County, VA
Occupation
Electrical Contractor
It would seem to make more sense to disconnect both the neutral and ground from a circuit, at the neutral bus, and then touch just the ground to test for improper EGC current.

That being said, I can't say that I would try this kind of troubleshooting live, as it seems unnecessarily dangerous. I'd opt for a clamp-on ammeter around the EGC first.
 
brother said:
The point is , it FOOLED my plug tester, didnt think of that. I just HAPPEN TO catch it cause one recepticle was smashed!! Just keep an eye out for "homeowner jackleg" LOL.

The point really is it wasn't the HO that did this it was a lazy EC. & now you've seen this "trick" adds are that at some point you too will do this.
 
77401 said:
The point really is it wasn't the HO that did this it was a lazy EC. & now you've seen this "trick" adds are that at some point you too will do this.


who ever u are, was it really necessary to say 'at some point YOU too will DO this''?? No WAY will i ever do this, seeing how dangerous of a condition this was.

I do not believe that any EC did this either, seeing that most of the work done on this building was done by previous HOME OWNERS. They were trying to save money i suppose.

I do like the trouble shooting idea about testing old homes from mike. I would just disconnect the neutral and ground at the main and test from there, (on a DEAD circuit of course).
 

haskindm

Senior Member
Location
Maryland
Part of the reason for this dangerous practice is the increased use of Home Inspectors. Many Inspectors do not understand that it is NEC compliant to install non-grounding replacement receptacles or to install GFCI protected grounding type receptacles on a circuit that does not include an equipment ground. (Of course the receptacles are supposed to be labeled "GFCI Protected AND No Equipment Ground, but I am sure many homeowners remove these labels) Many of these inspectors only understand that their tester shows an open ground and they write their report stating that there is a problem. People (homeowners, handymen, and "electricians) that don't know any better, install these false grounds to satisfy the inspector, because now his tester shows proper wiring. They don't realize that they have, in many cases, taken a legal, code compliant installation, and made it an unsafe installation in order to make a cheap tester give the correct indication. A little knowledge is a dangerous thing....
 
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