Do GFCI Outlets Need a Ground?

[ActionDave]

Not exactly...in fact, the fault is that some of the current fault path is through you or some other path and not entirely getting back to the neutral. I guess it is a matter of semantics. A EGC TO the GFCI is NOT required for it to work. An EGC is there to provide a secondary fault path for an overcurrent situation to trip the breaker or blow the fuse...

Refrigerator sitting on a wood floor, plugged into a GFCI receptacle, fed by an old two wire circuit with no equipment ground.....frayed insulation on the cord winds up causing a connection from the hot or the neutral to the frame of the fridge....
Does the GFCI trip?

 

[Vegas_sparky]

Also, what would the typical result be in the above scenario, except now the GFCI has an attached EGC, and all grounds are intact?

 

[Sponsor]

 

[JWelectric]

Refrigerator sitting on a wood floor, plugged into a GFCI receptacle, fed by an old two wire circuit with no equipment ground.....frayed insulation on the cord winds up causing a connection from the hot or the neutral to the frame of the fridge....
Does the GFCI trip?

Not until the third pat is made and then it opens at around .005 amps. Without the GFCI device then enough current has to flow that causes the fuse or breaker to open and this would result in death should a person be the third path.

 

[JWelectric]

Also, what would the typical result be in the above scenario, except now the GFCI has an attached EGC, and all grounds are intact?

With the GFCI device installed on a three wire circuit the device will open at .005 amps. Without the GFCI device the only protection is the fuse or circuit breaker.

Lets carry your scenario one step future. This frayed cord has a high resistance fault of say 10 ohms. No GFCI device. How safe is it now? 120 divided by 10 equates to 12 amps of current flowing on the case of the appliance and the fuse or circuit breaker is not opening.

In other words it is the GFCI device that is offering the protection not the equipment grounding conductor. This protection is there with or without the EGC.

 

[LLigetfa]

Refrigerator sitting on a wood floor, plugged into a GFCI receptacle...

There are many anecdotal reports of refrigerators tripping GFCIs even without a frayed cord.

If the humidity was high enough to have condensation on the wood floor then all bets are off. I remember one time at my parent's house getting tingles off a power cord (it was not frayed) behind the TV as I laid on a damp wood floor.

 

[DonL]

Also, what would the typical result be in the above scenario, except now the GFCI has an attached EGC, and all grounds are intact?

My guess is that you would have False Trips even in normal operation.

1 reason it is not a good idea to put a GFCI on a refrigerator, that has a safety ground. But I think NEC may now require it for a commercial install, And a Ground wire is required, But not for all dry location residential installs ?

It provides no extra Ground Fault Personal safety in your homes kitchen, If all appliances are wired properly.

 

[Jadnashua]

I think you are all missing the main point of the GFCI...if more than 5ma leaks somewhere rather than just going through the normal hot/neutral path That ground doesn't have to be through a ground connected to the GFCI frame, it could be through a water pipe, contact with the actual ground or whatever as long as it provides a low enough resistance to equate to a current of >5ma to flow with the available voltage. Take the example where the refrigerator frame is now hot. You walk up in your bare feet, touch the frame, the could GFCI will trip, regardless of whether it has a ground wire attached or not. Or, while touching the frig handle, you happen to touch the sink, again, you could easily trip the GFCI.

IOW, there are lots of things in the house that can provide a path for current, and it's not hard to get a low enough resistance to equate to >5ma which will trip the GFCI.

If your frig trips a GFCI, it is highly unlikely that it is a false trip...there's something wrong with it. The GFCI is just protecting you, should you touch it under just the right conditions from getting electrocuted. What's some food worth verses the life of you or your child? Fix it, or replace it. Next time you do touch it, may be your last otherwise.

 

[Reach4]

I think you are all missing the main point of the GFCI...

You think wrong.

The great majority of those posting on the thread know the point of the GFCI.

 

[Jadnashua]

A parallel path is easy to make...it does not have to be via the EGC. If there is one, and the current leak is >5ma, the GFCI will trip, ground wire or not. All that matters is that if the power going through the GFCI becomes unbalanced, then, it trips. It really doesn't matter how that path is created. IOW, if all of the power going from the black lead to the white lead has >5ma going somewhere else, there is a ground fault, and the device should trip, removing the voltage, and thus, protecting you. It really doesn't matter how it leaks out, it is a fault and the device reacts.

 

[DonL]

The simple answer is that the NEC requires a GFCI to have a ground. Or the new codes are wrong.

If a ground is not required, Then a GFCI is not required either. Is it ?

Please do correct me if I am wrong.

 

[Reach4]

The simple answer is that the NEC requires a GFCI to have a ground.

If a ground is not required, Then a GFCI is not required either.


Please do correct me if I am wrong.

You are wrong.

Sheeh. You are just saying this stuff to amuse yourself, right?

 

[Jadnashua]

The simple answer is that the NEC requires a GFCI to have a ground. Or the new codes are wrong.

If a ground is not required, Then a GFCI is not required either. Is it ?

Please do correct me if I am wrong.

On NEW construction, yes, you must install it with a ground. On retrofit, it is allowed to be installed (and functions perfectly fine) without a ground, and is a major safety upgrade and convenience issue if you have ancient 2-prong receptacles that after so many years, are probably long-past due to be replaced because of loss of temper on the contacts. It is much easier to make this upgrade verses rewiring the entire house. Now, at some point, they may make that a requirement, and you won't be able to do that retrofit, and, depending on the insulation on the wires, may be the prudent thing to do, but for now...you are perfectly within the code to retrofit and protect receptacles with a GFCI, AND any downstream receptacles could also be 'grounded - i.e., three-pring', but require the label indicating GFCI protected, no ground.

 

[Vegas_sparky]

Does a GFCI work without a ground? Yes, and they are a tremendous asset for protection of personnel.

An EGC on a GFCI recept can still help avoid a tragic accident, and make them better. It usually takes a combination of events to have something really bad happen.

Let's move to the garage, where there's a GFCI recept in a metal 4S box, an industrial cover, and fed by NM cable. You have an extension cord your friend borrowed, and he ran it over with a furniture dolly a few times, or hit it with his electric weed whacker. There are slight, unnoticed, abrasions in the sheath/insulation. One spot has a very small area of hot conductor exposed, another has a very small area of neutral exposed. Another has a very small area of ground exposed.

You use this cord to plug in the block heater for your truck.

Next time you go to leave, the cord is now laying in a puddle of water from the snow that's melted off the truck the night before. All of the abrasions are in the puddle. How would the GFCI typically perform with/without an EGC?

You pull the cord cap from the truck, and start wrapping it up by hand to get it out of the way. The abrasion with the exposed hot is unknowingly resting in your left palm. Your right hand slides down the wet cord for the next wrap and contacts the spot with the exposed neutral. You're getting hit, HARD. Chances are, a connected EGC would have prevented this.

In commercial/industrial environments, these types of circumstances are not atypical.

If your fridge trips the GFCI, first change out the device. If it trips the new one, fix the fridge. It has a problem that has developed over time. That does happen.

 

[Jadnashua]

If you end up being the only load, a GFCI won't protect you, but in the previous situation, considering it is wet, it's entirely possible that some of that current would end up going through your body to the wet surface, and then, the current would become unbalanced, and yes, it would trip protecting you. An EGC may or may not help in this situation. Nothing is guaranteed in life except you'll eventually die. A GFCI can often postpone that if you end up in a compromising situation where one is involved. A two-wire circuit with a GFCI is vastly safer than one without. There is an incremental gain if you actually also have an EGC, but nowhere near as much as adding the GFCI in the first place. Ideally, you'd rewire everything to replace that old wiring, but being realistic, since you can gain most of the benefits, most people just end up going with GFCIs, if they make changes at all.

 

[LLigetfa]

If your fridge trips the GFCI, first change out the device. If it trips the new one, fix the fridge.

GFCIs are not infallible. When I built my house, every GFCI that I had would trip from several of my power tools and no, there was nothing wrong with the tools. I have a chop saw that has a double insulated two-prong plug. When I release the trigger on it, an electric brake engages to stop the blade quickly. The brake unbalances the sensor and it trips. There is nowhere for any current to take an alternate path. It is the motor brake that generates the current.

I also have an electric brad nailer that uses a large linear motor and it too would trip the GFCIs. Again, there is no alternate path for the current to take. The collapsing magnetic field induces the current, similar to how an ignition coil works when the points open. Motor coils and magnetic fields can do that.

 

[ActionDave]

Not until the third pat is made and then it opens at around .005 amps. Without the GFCI device then enough current has to flow that causes the fuse or breaker to open and this would result in death should a person be the third path.

I knew in my heart we were on the same page just a different paragraph.

Just to be clear for anybody following along.....GFCI's are good, use them.
If you have opportunity to run a new circuit with a ground and combine it with a GFCI plug or breaker that is even better, do that.

 

[JWelectric]

Gentlemen, The only way a GFCI will trip is to have a difference between the two current carrying conductors of 6 milliamps or more.

Electric brakes, capacitors, resistors, inductors, or anything connected WILL NOT CAUSE THE DEVICE TO TRIP.

It is customary to blame a fault on anything other than what is to blame, “I didn’t do it” even our children use this line.

The bottom line is simple, the EGC has no role in how the device works. The EGC does not make it any safer. If a saw, freezer or frayed cords are tripping the device then the problem lies in the current path.

 

[LLigetfa]

Ja, and theory always works in a vacuum.

 

[DonL]

There are Gentlemen here ?

Theory only works perfect in a vacuum

 

[DonL]

GFCIs are not infallible. When I built my house, every GFCI that I had would trip from several of my power tools and no, there was nothing wrong with the tools. I have a chop saw that has a double insulated two-prong plug. When I release the trigger on it, an electric brake engages to stop the blade quickly. The brake unbalances the sensor and it trips. There is nowhere for any current to take an alternate path. It is the motor brake that generates the current.

I also have an electric brad nailer that uses a large linear motor and it too would trip the GFCIs. Again, there is no alternate path for the current to take. The collapsing magnetic field induces the current, similar to how an ignition coil works when the points open. Motor coils and magnetic fields can do that.

You need all new tools.

Just tell your wife JW told you so. Good reason to upgrade.

Don't look a gift horse in the mouth.

I have seen exactly what you have.

But my wife says I have to many tools already.

The only place I use a GFCI is on outdoor outlets. With a Ground connected. And I use a 3 conductor extension cord.


Have Fun Everyone.