GFCI's do not need an EGC (moved from another thread)

[don_resqcapt19]

Bottom line: a GFCI will function for its specified purpose (limiting shock current to a specified generally acceptable value) without and EGC. But it will be far more effective at its accepted purpose (preventing shock) with an EGC present.

-Jon

I have to take issue with the last part of your post. A GFCI does not and cannot prevent shocks...it can only limit the duration of the shock.

 

[gar]

080721-1044 EST

Some references:
http://hyperphysics.phy-astr.gsu.edu/hbase/electric/shock.html
http://hyperphysics.phy-astr.gsu.edu/hbase/electric/shock.html#c3

http://www.lockergnome.com/blade/2008/01/18/dell-says-electrical-tingle-sensation-is-normal/
I suggest that Dell should eliminate the tingle.

This one is unrelated.
http://www.nytimes.com/2008/04/01/science/01obshoc.html?ref=science

http://ieeexplore.ieee.org/xpl/freeabs_all.jsp?arnumber=4091891
Requires IEEE membership.

http://www.egr.msu.edu/age//extension_outreach/bibliography.htm
Many references listed. Much of this relates to cows and the farm stray voltage or current problem.

Many other references if you do a Google search.

.

 

[winnie]

I have to take issue with the last part of your post. A GFCI does not and cannot prevent shocks...it can only limit the duration of the shock.

Yet a further refinement that I agree with.

The _specification_ of the GFCI device is to limit the duration of certain faults which carry current outside of the intended circuit.

An effect of meeting this specification is that _most_ shocks will be reduced in duration. But if the current passes through a person, they will experience a shock.

Again, this does speak to the _need_ for an EGC if you actually want to prevent shocks, as opposed to reducing their intensity. The combination of a GFCI and an EGC will mean that the GFCI often trips _before_ any significant current passes through a person, because sufficient trip current passes directly to the EGC.

-Jon

 

[cschmid]

one thing about the (steak) cow should be nice and tender now..lets grill...:grin:

I understand this whole arguement..I understand why when a GFCI fails people tend to think it was because of no ground and it was on a 2 wire circuit..when in essence I believe there is a shelf life to the electronics in them..there have been several recalls on GFCI and I believe the last on was on Hubble's GFCI outlet due to malfunction..

So due they always fail in a open state no some times they fail in a closed state so they just work like an receptacle works..so go ahead and whin..just like the AFCI there will be some fail on regular basis and there will be recalls..maybe someone will have the authority and knowledge to get some corrections done..

 

[brian john]

I am no ones pet.

Bob aka IWIRE is the last person I would think of as anyones pet, but when I read the post I sort of knew it was directed RIGHT AT BOB. Not sure why I felt this way?

 

[billsnuff]

Veerrry Interesting

Veerrry Interesting

After reading this thread i think i am taking away the following:

old house, 2 wire romex. Is it a cost effective way to enhance the safety of the home by replacing recept with GFCI's........i believe so. Is it a cost effective way to enhance the safety of the home by supplying GFCI and ECG's. Perhaps not depending on the client.......How much safety can they afford in compliance with the NEC. JMSO.

 

[cowboyjwc]

I agree that they do not need a ground to operate, but do not use your plug in tester to check them if they do not have a ground.

 

[electricalperson]

everyone who is confused about GFCI's should get the book overcurrents and undercurrents by earl roberts.

a GFCI without a ground will still trip. a tester will not trip a GFCI that does not have a ground. press the button on the gfci if that works then the gfci is fine. if it doesnt then the gfci probably needs replacement and has nothing to do with the equipment ground.

 

[electricalperson]

a way to test a gfci without an equipment ground is to run a wire from the water pipe and use a low impedance meter (wiggy) and go from the ungrounded conductor to the wire connected to the grounded waterpipe. that will trip the GFCI. ideal makes an attachment for the suretest circuit analyzer. i believe its the ground continuity adapter

 

[weressl]

No, I don't agree to disagree.

This is not a subject open to interpretation, you are simply wrong that a GFCI needs a ground to operate.

That may seem rude but the subject is an important one and I don't want any newbies going away thinking GFCIs need a grounding means to operate.

Why not?

After we are done with this, we can argue about gravity...........

 

[iwire]

After we are done with this, we can argue about gravity...........

Gravity..... another scam by the govt.

First they get us to believe in it, then they will tax us on it. :wink:

 

[weressl]

Yeah, whatever you want to believe is up to you, those that understand how a GFCI works know that an EGC has no bearing on whether a GFCI will work as designed and they also know that if you are across the ungrounded and grounded conductor of a GFCI protected circuit with or without an EGC, you will be shocked or electrocuted, but once again, this has nothing to do with this thread.

If you want to start another thread on your belief go for it, but you have already argued this same point before and were shown with substantiation that you were wrong.

Roger

I agree 100% that the residual current principle does not require grounding wire to actuate the GFI, however it does need to find a circuit path to the grounded conductor.

Could we agree that when an equipment that is equipped with a grounding conductor will activate the GFI faster if there is a ground fault to the metallic case whereas the same equipment that has no ground conductor and resting on an insulated surface - dry wooden table for example - will only trip when you touch it?

 

[weressl]

Gravity..... another scam by the govt.

First they get us to believe in it, then they will tax us on it. :wink:

Would Obama do such thing? Ye must jest!

 

[iwire]

Could we agree that when an equipment that is equipped with a grounding conductor will activate the GFI faster if there is a ground fault to the metallic case whereas the same equipment that has no ground conductor and resting on an insulated surface - dry wooden table for example - will only trip when you touch it?

I think that is a pretty much a sure thing.:smile:

My experience as anecdotal as it may be is that if you short 'hot to ground' in circuit that is down line from a GFCI receptacle that the breaker will trip at the same (well close) to the same time as the GFCI trips.

The GFCI receptacle will also very likely be toast.

 

[cowboyjwc]

I do not believe that gavity exists and I will plant my feet firmly on the ground and argue that with you. :grin:

 

[480sparky]

I do not believe that gavity exists and I will plant my feet firmly on the ground and argue that with you. :grin:

It's not gravity that holds me to the earth. It's all those hungry, free electrons in my body somehow searching for that mystical buffet below my feet called the ground.

Either that, or heaven is repelling me.

 

[weressl]

I think that is a pretty much a sure thing.:smile:

My experience as anecdotal as it may be is that if you short 'hot to ground' in circuit that is down line from a GFCI receptacle that the breaker will trip at the same (well close) to the same time as the GFCI trips.

The GFCI receptacle will also very likely be toast.

I am enclosing the UL GFCI trip requirements. It is WAY faster than any TM circuit breaker can be. The standard 20A QO T/C curve is just too large of a file to include it here, but y'all can look at it at http://ecatalog.squared.com/techlib/docdetail.cfm?oid=090089268011800a

 

[iwire]

I am enclosing the UL GFCI trip requirements. It is WAY faster than any TM circuit breaker can be.

OK, it did not happen. :grin:


I guess it could have been --- Short>>>GFCI tries to open> blows apart > breaker opens

But I did not due a forensic investigation.

 

[gar]

080721-21621 EST

weressl:

I agree 100% that the residual current principle does not require grounding wire to actuate the GFI, however it does need to find a circuit path to the grounded conductor.

Suppose I connect one terminal of a battery to the input hot wire and the other terminal to the hot output slot of the GFCI. This will trip the GFCI. Do you classify this as a path to the grounded conductor?

I used a battery here just for convience because it is an isolated energy source.

.

 

[weressl]

080721-21621 EST

weressl:


Suppose I connect one terminal of a battery to the input hot wire and the other terminal to the hot output slot of the GFCI. This will trip the GFCI. Do you classify this as a path to the grounded conductor?

I used a battery here just for convience because it is an isolated energy source.

.

Strawmen argument.

You are using the device as it is not intended to be used, yet you are trying to ask me a question relating to its inteded use.