Originally Posted By: fbuttermore This post was automatically imported from our archived forum.
Inspected a recently redone 1955 ranch today. All service, meter, panel, receptacles, switches and fixtures new. All grounds (3 of them in all) terminate correctly, panel wired properly, etc,etc,etc. All in all, a fine re-fab on this house.
—> Here’s my question: I found several receptacles with an open ground. They all tested OK and some outlets within the same room (other wall) were grounded OK. All GFCI responded correctly.
1) What might be causing this?
and
2) How dangerous is it?
I recommended calling in a sparky to further evalute.
Originally Posted By: bking This post was automatically imported from our archived forum.
Sounds like the wiring was not updated and the outlets that check ok have a bootleg ground from N to G.
Use a good DVM on low AC scale and if you have less than one millivolt between N and G at an outlet, that outlet has a false ground.
You should begin with the meter on higher scale and use plug and cord to your meter to elimimate bad connections and voltages from your fingers on the test leads. Most meter leads will not probe into a recept. the slot is too small.
Originally Posted By: pabernathy This post was automatically imported from our archived forum.
fbutter,
Sometimes in a remodel the slackers way of taking care of it is to ground what is easy and forget what is hard to ground. Doing tests are one thing but if you have a reliable tester and it is saying open grounds yet you take it to the other wall and get the "ALL OK" signal...then write up the walls in question and do as you did refer it to an electrician.
Getting into ALOT of testing beyond what you have listed may just push you over the SOP line.....note it and recommend an Electrician as stated but just so you know I see this all the time......called a half wired room in that they tend to fix the easier plugs in the center walls and leave the outside walls and just replace the recept...which is a violation in itself...
Anyway...you did the right thing as it takes the liable off of you because you noted it and suggested furthur evaluation.
-- Paul W. Abernathy- NACHI Certified
Electrical Service Specialists
Licensed Master Electrician
Electrical Contractor
President of NACHI Central Virginia Chapter
NEC Instructor
Moderator @ Doityourself.com
Visit our website- www.electrical-ess.com
Originally Posted By: pabernathy This post was automatically imported from our archived forum.
The grounded (often a neutral) conductor can generally be connected to the ground only at the service disconnecting means neutral bus [see 250.24(A)(5) and 250.142(B)]. The main bonding jumper at the service connects the grounded conductor and equipment grounding conductor together at that point. The main bonding jumper serves as a vital link in the ground-fault current path from the service disconnect to the source windings (usually a utility transformer). . Sometimes through error or ignorance, the grounded (neutral) conductor and equipment grounding conductor are connected together on the load side of the service disconnecting means which violates the general requirements of 250.24(A)(5). This is often referred to as a false or bootleg ground and can create unwanted or objectionable current in the grounding circuit. If the grounded conductor and equipment grounding conductors are connected anywhere else in the building, all grounded metal can become part of the grounded (neutral) conductor return circuit for unbalanced neutral current that can create various voltage potentials on electronic equipment. When using common receptacle testers, this condition typically shows up as normally wired.
Here is where the hazzard lies : "If the grounded conductor and equipment grounding conductors are connected anywhere else in the building, all grounded metal can become part of the grounded (neutral) conductor return circuit for unbalanced neutral current that can create various voltage potentials on electronic equipment"
Now...enough of the verbal mumbo jumbo.....here is the skinny on the subject. You have a circuit that tests as NO ground...yet it probably has a 3 plug recept in it......I would cite that as a violation and explain to them you concerns...YOU have to be tactful as we all know referals are you best resource and scaring someone will not get you another call from the agent that hired you.....
So I would note it as a hazzard that warrants review as soon as possible from a licensed electrician and is about all you can do really....Now the electriican will come and pull the plug itself...check for grounding visually and then check it again with meters....but I can't tell you it is a hazzard that is so urgent that it can't wait for an electrician to check it but it does need to be a priority issue reported on your report.
You may have what bking has stated in that the ones that check out fine may in fact be a bootleg as described above ( which is not my definition mind you... ) so an electrician will be able to verify this by not only checking the system itself but the connections as well.
You stated that the grounds all look fine, can you verify the house was rewired....versus just a simple upgrade of the service system....big difference you know.....
At any rate.....I would note it as ODD and not normal and again refer it to an electrician....IF the recepts in the home are 3 hole models which I will assume....since you did not state otherwise and in most remodels they would be...something smells here.....most certainly note that also and have a electrician look a that as well.
-- Paul W. Abernathy- NACHI Certified
Electrical Service Specialists
Licensed Master Electrician
Electrical Contractor
President of NACHI Central Virginia Chapter
NEC Instructor
Moderator @ Doityourself.com
Visit our website- www.electrical-ess.com
Originally Posted By: fbuttermore This post was automatically imported from our archived forum.
Paul, again thanks. Everything on one side of the house wiring-wise was new. All recepts, switches, fixtures in entire house new as well. New grounds(s) going outside and to the water meter. New panel, 100A service, new meter, breakers and most wires looked new or almost new coming out of the box. They even added the correct/seperate GFCI circuits. That’s why this was so puzzling…everything appeared to be done with care. I still think that they let some of the old wire slide and just added 3-prongers. It was about 15-20% of the recepts that tested open ground. I recommending having that issue evaluated and negotiate whatever fix was deemed appropriate in the price…
Originally Posted By: pabernathy This post was automatically imported from our archived forum.
NO proble frank…you did the right thing.
They need to have the plugs pulled that are giving the open reading and looked at. Chances are like I said they are ones on the harder to reach places of the upgrade and might have simply tapped on to the existing wiring to those which kinda defeats the purpose....
The best way to know if they did all new wiring is to see if their are any junctions above the updated panel area....find it always hard to believe someone does a upgrade and still goes with a 100A panel.....geesh it does not cost that much more.
-- Paul W. Abernathy- NACHI Certified
Electrical Service Specialists
Licensed Master Electrician
Electrical Contractor
President of NACHI Central Virginia Chapter
NEC Instructor
Moderator @ Doityourself.com
Visit our website- www.electrical-ess.com
