I recently did an inspection on a home that had been renovated by a licensed GC who had an inspection performed after renovations. Home is under contract and I was hired to do a pre-purchase inspection as my client did not simply want to rely on builders inspector. So far I have found about $10,000.00 worth of repairs / issues that need to be addressed including structural.
One of the many points of contention is with the electrical system; builder & his inspector said that GFCI’s are acceptable for ungrounded outlets (which I agree) that they can be used for circuits down line (no problem there) and they they do protect any device plugged into them (which I highly disagree).
Correct me if I am wrong however my understanding is that:
GFCI’s can be used in place of ungrounded receptacles AND used for those ungrounded receptacles down line on the same branch circuit.
All receptacles must be labeled GFCI protected AND Ungrounded Equipment in such cases.
GFCI’s receptacles on ungrounded receptacles afford NO PROTECTION
to equipment even when surge protector is in use on an ungrounded gfci protected receptacle…surge protectors only operate correctly (or within their warranties) when same are properly grounded.
Ungrounded GFCI’s do offer protection to personnel, even without a grounding connection.
Without the grounding connection, a fault in the appliance will not trip the circuit breaker (which is essentially the reason for the ground), but it will still trip the GFCI device when an unbalanced load is detected.
I know there has been disagreement as to use of GFCI’s downline however everything I have researched and speaking with my own electrical contractors validates my position…appreciate the feedback.
I think the builder is more upset with the previous home inspector…add to the fact he just dropped the price of the home $10,000.00 and now I find approximately another $10,000.00 in repairs…frustration is coming out.
Fortunately it was not a Nachi Inspector who missed all this stuff…typical franchise company that I have gone behind before and find all sorts of crap.
The one good thing about this disagreement is that it is completely unfounded. An ungrounded GFCI device offer more protection than a regular receptacle with a ground.
Okay I will attempt to answer each one
Yes a two wire receptacle or one without an equipment grounding conductor can be replaced with a GFCI device and any three wire receptacles downstream can also be protected by this device
Yes they are required to be labeled but we all know that these little stickers don’t stay in place very long
This is very false. The GFCI device does offer protection to the equipment as well as to the person interacting with the equipment.
Surge devices do work without an equipment grounding conductor. They shunt the current to the neutral which is always connected to earth by the utility company on the supply side to the transformer supplying the building.
The conditions we are speaking of are not allowed in new construction. Using GFCI’s in place of ungrounded, grounding-type receptacles is allowed only for “replacement” of ungrounded, non-grounding-type receptacles. Did that make any sense?
New construction would require modern three-wire systems, with grounded, grounding type receptacles. However, you may add GFCI protection to any circuit.
This is a home 60 plus year old…the GC (builder) got it fairly cheap and wanted to do a fix and flip. Permits were supposedly pulled of which I have ask them to supply documentation to my client.
Joseph,
Do you have any documentation to support your statement in regards to GFCI’s on an ungrounded branch circuit offer equipment protection.
While I understand how a GFCI works in monitoring the balance between the hot and neutral, the ground is what dissipates the energy…during a surge the energy is still going downstream.
Every warranty I have read from a surge protection device states that the receptacle their surge protector is plugged into MUST be grounded.
[FONT=Times New Roman]If you truly understand how a GFCI device works then there is no need for documentation.
Every branch circuit installed from 1897 till this date is grounded. The conductor we have come to call the neutral conductor is bonded to the grounding electrode both at the service supplying the circuit as well as at the secondary of the transformer supplying that service.
A three wire receptacle has two conductors that are connected to the ground rod at the service, the neutral and the equipment grounding conductor. With the equipment grounding conductor any faulted current is carried back to the service neutral where both conductors land on the same terminal bar.
A surge protector shunts the current back to the neutral not to the ground rod. In order for current to flow there must be a complete path from the source back to the source just like any flashlight you may own. There is no earth connection in your flashlight and it works fine. It would work just as well if there was a conductor that connected it to earth but it wouldn’t be as portable.
With a ground fault device should the exposed metal parts of a piece of equipment become energized and someone come in contact with that metal it would take only a difference of .005 amps to clear the fault.
On a three wire receptacle that has no GFCI protection and exposed metal become energized and someone comes in contact with the energized metal it could take a very long time for the breaker to trip.
As a general rule of thumb most breakers will carry 135% of their rating for up to two hours. Most breakers will allow up to six times their rated current to pass for two seconds.
Let’s take a common 15 amp circuit found in our living and bed rooms. This circuit will let through about 90 amps for two seconds. If the same circuit was GFCI protected the same fault would clear when the faulted current reaches .005 amps for two cycles or .033 second. This device will clear with or without an equipment grounding conductor.
The clue to what?
If there is no equipment ground what does that mean?
Think about what you are saying, it is simple. Where does that equipment grounding conductor connect after it leaves the receptacle? Is it the same place that the neutral conductor lands?
Both land on the same bar in the service equipment.
I have explained my credentials here many times before. I attended NC State. I hold the highest level electrical contracting license the state of NC offers. I hold a Level III (the highest level) electrical inspector’s certificate. For the past 13 years I have been teaching electrical theory classes at the community colleges or should I say at least four of them.
I sit on the education committee for the NCIAEI and am a member of their board of directors. I spend several hours a year with some of the greatest minds in the electrical field. Some of the people I spend many hours with are the electrical engineers for the Office of the State Fire Marshall, UL, Met Lab, and many many more. Check out this link and click on committees and officers buttons; http://www.nciaei.org/
I am bright enough to hold a receptacle in my hand and identify each screw on it and tell you where each conductor originates. The black one on the breaker, the white one and the bare one on the same terminal bar in the panel.
Power comes in on the black wire and supplies the electrical components of an appliance and returns to the panel via the white wire. The bare wire (the equipment grounding conductor) connects to any exposed metal that is not part of the electrical components in case something goes wrong with the appliance the current can be carried back to the same place the neutral wire attached. This path is established in order that should the metal become energized there is a low resistance in the circuit and the breaker trips.
With a GFCI device without an equipment grounding conductor should the exposed metal become energized and a person come in contact with that exposed metal and a current of .005 amps flow from the exposed metal through that person and through earth back to the grounding electrode then back to the neutral the GFCI device opens.
This is a myth. There is no current that leaks out. The equipment grounding conductor is a low impedence path for fault current to follow in the event of a fault in the hot conductor. It is installed in order to trip the breaker or blow the fuse.
And will work just fine on a two wire system and is perfectly safe in a GFCI device with or without an EGC
This is true but the EGC does not offer any protection from shock. If there is a high impedance fault the person using that receptacle with an EGC and no GFCI is in a real danger but install a GFCI device and the danger goes away.
Because the bootleg ground is connecting the appliance to a current carrying conductor. Remember that the white wire is a current carrying conductor but the EGC only has current when there is a fault
Thanks Mike for Continuing to explain things well .
I and many others I am sure do appreciate you continuing to share your knowledge . Much appreciated … Roy
Mr. Larson, just because you might disagree with me does not make me wrong, does it?
This is good. As we both know health care is a whole world in and of itself. My experience in this line of work is I am a certified instructor in hospital electrical safety.
Herein lies a myth. In order to have current flow there must be a complete path from one potential to another and opposite potential. The potential that builds through magnetic induction is faced each and every time we travel under high voltage power lines. The redundancy in health care grounding has to do with equipment that is connected to the patient.
I did not imply anything you said. As a matter of fact at each quote you can click on the little arrow and it will take you back to the original post.
Oh please, if I touch a piece of equipment that was intended to be at ground potential and I am also on wet floor or touching a plumbing fixture or have a catheter in my body the current WILL flow through me.
You know that so why argue about it?
I used to teach electrical safety to physicians and nurses and OR and ICU staff.
I appreciate your posting here but there is no need to repeat false or incomplete information.
Bully bravo but this doesn’t make you right either.
You are trying to take an area that not only requires grounding but requires it to be installed twice and trying to compare it to a two wire receptacle. All the instruction background in this world will not make the two the same.
In health care where there is such strong requirements for grounding in redundancy there can be no GFCI devices used either.
In order for current to flow at all it must be between two potentials. Induced voltages without a complete path from the source being induced back to the induced source current cannot flow, basic physics of current flow. Current will always be flowing between two potentials.
All this bull about leaking current going to or seeking earth is just that, bull.
None of this has a thing to do about a GFCI device on a two wire circuit and the safety of the device should someone plug something into it that has a three wire cord.
As long as you want to keep it on this topic I will be glad to discuss it with you but I will not let you use me to highjack this thread to talk about health care facilities. If you would like to discuss this aspect of electrical use please start a new thread.
For the sake of this discussion let’s say I have an old metal cased drill that has a three wire cord. I have a three wire receptacle that is not protected by a GFCI device and a three wire GFCI receptacle that has no equipment grounding conductor.
I am using the three wire circuit that has an EGC but my little drill has a high impedance ground fault in one of the windings that is letting current flow on the case of the drill to the EGC. I am standing in ankle deep water with a saline base. I could possible die from the current that is flowing through my body through the wet contact with earth to the ground rod at the meter up to the neutral from the supply utility.
The amount of current it will take to clear the overcurrent device will be a lot more than the rating the breaker or fuse.
In this scenario I am in parallel with the EGC and the amount of current flowing through each path will be dependent on the amount of resistance of the two paths. Yes more current will flow on the EGC than through me but current will be flowing through me none the less.
Until this current reaches the trip curve of the fuse or breaker the current will continue to flow through both paths unless one or the other is broke such as the reflex causes me to lose grip on the drill and it falls from my hand.
Now the same scenario but this time using the GFCI receptacle that has no EGC. Once the current flowing through my body reaches a level of .005 amps for a period of .033 seconds the GFCI will open and it will do it with or without any EGC.
There is no need for an EGC on a GFCI device and it don’t matter if the equipment has a three wire cord or not.