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GFCI Grounding Discussion (from Power to shed via extension cord)

GFCI Grounding Discussion (from Power to shed via extension cord)

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  #1  
Old 12-11-12, 05:31 PM
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GFCI Grounding Discussion (from Power to shed via extension cord)

Considering it only take 100mA to stop a human heart a ground spike near the shed wouldn't do any harm. I know you are thinking the shed will be on the up side of the GFCI so why fool with a solid ground. GFIC's work as ground faults. I know that Pablodepinto is not going to be arc welding, bear foot while standing in water, but assuming that the extension cord has a bad ground it would be nice to have the peace of mind that you have a good ground at the shed.
 
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Old 12-11-12, 06:46 PM
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Please explain to me how a ground rod would address any of that.
 
  #3  
Old 12-11-12, 07:22 PM
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OK. bad ground feed from the house. no ground in the shed. One poorly wired power tool. Touch tool and conduit. Dead person on the ground. Really bad Christmas.

OR. bad ground feed from the house. Ground tie-in at the shed. One poorly wired power tool. Keeps popping the breaker. Touch tool and conduit. No worries circuit is dead not YOU! Happy Christmas to all.
 
  #4  
Old 12-11-12, 07:39 PM
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Do you honestly think that the earth between the shed and the house will have a low enough resistance to allow sufficient current to flow to trip the circuit breaker in the house? Trust me, it won't.

What you have described is why ground fault current interrupters (GFCIs) were invented. A GFCI does not require a connection to the earth to function.
 
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Old 12-11-12, 08:01 PM
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But it does need a ground.

Either way it was just a suggestion, and "IF" a ground spike was used you would lose nothing and at the very least get a neat lightning rod (don't bite my head off. I know lightning would hit the house before it hits the shed, but who knows).
 
  #6  
Old 12-11-12, 08:37 PM
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As Furd said, a GFCI does not need a ground to operate. If you had a 2-wire circuit and touched the hot wire while standing in a puddle of water, the GFI will trip before you feel much of anything.

(Granted, don't try this at home... but that's what they were designed for).
 
  #7  
Old 12-11-12, 09:03 PM
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But it does need a ground.
No, a GFCI device does not need a ground. Just out of curiosity, what do you think the difference is between
Originally Posted by Furd
a connection to the earth
and
Originally Posted by EnclosedVisions
a ground.[?]
Here's a question for you: If I have a house that was wired in the 1950s, and there are no ground wires nor any other means of bonding to ground at any of the receptacle outlets, is there a way that I can install three-slot receptacles in those outlets without running new wire to them - and be in full compliance with the requirements of the National Electrical Code?
 
  #8  
Old 12-11-12, 09:18 PM
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I would make sure that everything is grounded (this is very important). You might want to consider placing a ground spike near the shed.
Installing a separate Grounding Electrode Conductor for this application would be a waste of both time and money. Better to invest those assets where a measurable return can be expected.

I would also suggest that you buy a Multimeter.
I'm not clear why the OP would need a multimeter to do this project safely. If he did want to buy one, it should be an analog multimeter, not a digital one, in order to screen out readings from induced voltage.

This will allow you to test your outlets, plugs and lighting without having to apply 110V AC.
You have a multimeter that will test for voltage and correct wiring on dead conductors? I want one of those! Where did you get it and who made it?

Oh, just as a note, we don't have 110V AC power here in the US. It's 120/240V single-phase service.

Buying a better-quality extension cord is probably a good idea. I actually buy mine at electrical supply houses. However, the worst that is likely to happen if you buy one that isn't capable of handling the load is that it will fail and you'll have to replace it.
 
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Old 12-12-12, 02:28 AM
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As I am an engineer, I sometimes forget that not everyone knows how to use a DVM(Digital Voltage Meter synonymous with Digital Multi-Meter) or even what it is. In this regard I meant that Pablodepinto could installing electrical outlets (on an uncharged circuit) and easily test for wiring short by testing for continuity (which is a fancy way of testing for very low resistance which would be present if two or more wires were unintentionally touching). Next remote-outlets can be tested by deliberately shorting prongs and testing for continuity. I guess if you didn't have the money for a DVM you could simply buy a battery powered continuity light indicator tester. DVMs are quick and easy and as an addition to any Do-It-Yourselfers tool chest a DVM has literally hundreds of usages from complicated to simple, home and automotive.

A tail of caution: My in-laws bought a cheap extension cord that was 100'. They ran it out about 20' from their house and coiled the rest up in a flower pot. After two weeks of trickle charging his cars battery in the winter, my father-in-law noticed that all the coiled cord that was in the flower pot had fused its outer casing together. The cord was ruined. Mostly I see cheap cords form cracks in the outer insulation. Don't get me wrong, I am cheap, but some things cost you more in the long run.

Pablodepinto, Do you plan on running conduit or romex?
 
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Old 12-12-12, 03:04 AM
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Here's a question for you: If I have a house that was wired in the 1950s, and there are no ground wires nor any other means of bonding to ground at any of the receptacle outlets, is there a way that I can install three-slot receptacles in those outlets without running new wire to them - and be in full compliance with the requirements of the National Electrical Code?
How to Ground an Electrical Outlet In an Old 1950s House With No Grounding Wire

Ground an electrical outlet with no grounding wire by installing a GFCI(Ground Fault Circuit Interrupter) receptacle as the fist outlet on the circuit you want to ground. The NEC(National Electric Code) as of October 2012 allows three prong GFCI outlets to exclude ground wires due to the built-in breaker switch that trips at the indication of a short. An electrician may insist on grounding a GFCI during installation, but it is not required for most applications. A GFCI without ground wiring is not considered safe for computers, or microwave ovens, but it will accommodate all other household electrical items.

"Thanks for the homework NashKat1." I was unaware that GFCI's could be installed without a ground at all, as Furd said. My mind is blown.
 
  #11  
Old 12-12-12, 06:57 PM
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EnclosedVisions

As I am an engineer
Ground an electrical outlet with no grounding wire by installing a GFCI(Ground Fault Circuit Interrupter) receptacle as the fist outlet on the circuit you want to ground. The NEC(National Electric Code) as of October 2012 allows three prong GFCI outlets to exclude ground wires due to the built-in breaker switch that trips at the indication of a short.
Ummm....as an engineer, is that really what you believe?
 
  #12  
Old 12-12-12, 07:44 PM
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CasualJoe (Member since Jan 2010)

Ummm....as an engineer, is that really what you believe?
NashKat1's question had specific parameters and this was the only solution that fit. I love learning. That is the whole point of living. So, Break me off some knowledge CasualJoe. Enlighten us (or just me).
 
  #13  
Old 12-12-12, 08:42 PM
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Installing a GFI does not provide a ground on an ungrounded system. The GFI will function as designed.

EV, do the math an see if a short directly to a ground rod at 25 ohms resistance will ever trip a breaker and report back.
 
  #14  
Old 12-12-12, 08:44 PM
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"406.3(3)(c) A non-grounding-type (two hole) receptacle(s) shall be permitted to be replaced with a grounding-type (three hole) receptacle(s) where supply through a ground fault circuit interrupter. Grounding-type receptacles supplied through the ground fault circuit interrupter shall be marked "No equipment Ground" and "GFCI Protected". An equipment grounding conductor shall not be connected between the grounding-type receptacles."

This is from the 2008 edition of the NEC, but this code has been in the NEC for quite some time.

Note: A GFCI will not provide any protection on a line to neutral "short". Only a line to ground "short". Short is quoted because it really is not a good term to use when talking about GFCI's. It is more a leakage to ground that the GFCI protects people from shocks. If an electrician is working on a live circuit with a GFCI before them, and they get across the line and neutral, they will still receive a shock. The GFCI will do nothing.

There is no 2012 NEC code. There is 2008 and 2011. Next one will be 2014.
 

Last edited by pcboss; 12-12-12 at 08:55 PM. Reason: corrected date
  #15  
Old 12-12-12, 08:55 PM
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"pcboss Forum Topic Moderator

Installing a GFI does not provide a ground on an ungrounded system. The GFI will function as designed.
You are right but it does protect that ungrounded system, and is an acceptable practice under NEC. Don't believe me?... Read on.

"Nashkat1 Forum Topic Moderator

A GFCI device does not need a ground. Just out of curiosity, what do you think the difference is between a connection to the earth and a ground.
"Furd Member Since Mar 2006

A GFCI does not require a connection to the earth to function.
 
  #16  
Old 12-12-12, 10:17 PM
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NashKat1's question had specific parameters and this was the only solution that fit.
Interesting. The "specific parameters" in my question were
Originally Posted by Nashkat1
If I have a house that was wired in the 1950s, and there are no ground wires nor any other means of bonding to ground at any of the receptacle outlets, is there a way that I can install three-slot receptacles in those outlets without running new wire to them - and be in full compliance with the requirements of the National Electrical Code?
The answer to that question isn't
Originally Posted by EnclosedVisions
How to Ground an Electrical Outlet In an Old 1950s House With No Grounding Wire
Providing GFCI protection to the circuit is the answer to the question I asked. But GFCI protection does not create a path to ground. It monitors the difference between the potential on the ungrounded conductor and the potential on the grounded conductor, and opens the circuit when a minimum level of difference is exceeded.

Three-slot receptacles may be installed in compliance with the NEC, without a ground conductor, if they have GFCI protection. Tolyn explained it fully, including the required labeling, in post #23.
 

Last edited by Nashkat1; 12-13-12 at 12:33 AM. Reason: clarify and simplify
  #17  
Old 12-12-12, 10:28 PM
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DVMs are quick and easy and as an addition to any Do-It-Yourselfers tool chest
We recommend that members use an analog multimeter, with its superior filtering of induced voltage, rather than a digital multimeter.
 

Last edited by Nashkat1; 12-13-12 at 12:30 AM. Reason: clarify and simplify
  #18  
Old 12-12-12, 11:35 PM
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When someone says stuff like:

Nashkat1 Forum Topic Moderator Since Mar 2012

"One way of hearing what you just said"
They are either a politician, someone trying to start some mess, or someone having a bad day. You don't need to interpret my words. I may have poor spelling but I think it is quite easy to follow what I am saying. I don't come here to berate or argue with other members. I come here to learn and possible help others. And Nashkat1 I thought you were honestly asking me a question. Even though it was off topic. I took my time to answer it:

EnclosedVisions Member Since Dec 2012

"Ground an electrical outlet with no grounding wire by installing a GFCI(Ground Fault Circuit Interrupter)"
You belittle me and tell me the answer is:

Nashkat1 Forum Topic Moderator Since Mar 2012

"Providing GFCI protection to the circuit is the answer to the question I asked."
If I have said anything to offend you then I apologize, but this is no way to teat new members. If you have a valid criticism then I am all ears, but let's stay on topic. I am sure pablodepinto also a Member Since Dec 2012 would appreciate the common curtsey.
 
  #19  
Old 12-13-12, 06:00 AM
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The problem is when your answers are a little bit right and a little bit wrong. That can confuse a member we are tiring to help. We have to go back and correct the wrong parts or the member asking the question may take away the wrong info.

I'm a poor speller too but I use a browser (Firefox or Seamonkey or Opera) that clearly indicates which words are misspelled. Sure I may miss one occasionally but I go through my post at least twice to keep that to a minimum.

Help in helping members asking questions is always appreciated just be careful to give as correct an answer as you can and be graceful and polite if corrected. Heck, I get corrected by the pros here almost every day. I just add that to my knowledge and try harder not to write anything I'm not sure of..
 

Last edited by ray2047; 12-13-12 at 02:51 PM.
  #20  
Old 12-13-12, 07:05 PM
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So, Break me off some knowledge CasualJoe. Enlighten us (or just me).
pcboss and Tolyn pretty well covered it, but I will add emphasis on:

The NEC(National Electric Code) as of October 2012 allows three prong GFCI outlets to exclude ground wires due to the built-in breaker switch that trips at the indication of a short.
The "Test" and "Reset" buttons on a GFCI receptacle ARE NOT a circuit breaker.
 
  #21  
Old 12-14-12, 10:14 AM
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Maybe a Sparky can correct me.. please do.

The purpose of a Ground Rod is not to protect a person. That is accomplished by having the ground and neutral tied at the panel. (and only the first panel) Should a short to ground occur in an appliance the breaker will trip, and the appliance frame will not be "hot".

The Ground rod is to dissipate lightning/static to EARTH Ground, and hopefully not damage your wiring or appliances. The reason its required for detached buildings is again to hopefully direct a lightening strike to earth, and not travel to the other building.
 
  #22  
Old 12-14-12, 10:27 AM
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Tribe fan, you have a good understanding of both issues. The bonding of the neutral and ground at the first point of disconnect is what causes the breaker to trip.

The grounding electrodes like rods are for high voltage event like lightning strikes.
 
  #23  
Old 12-14-12, 11:32 AM
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I am closing this thread. ( If someone feels the need to open this back up feel free)

The original post #1 was apparently moved from another. I see no correlation.

No direct question was asked IMO and this is just going no where. ( Don't want it to get ugly)

If anyone has specific electrical questions, please start a new thread.

Thanks.
 
  #24  
Old 12-14-12, 09:09 PM
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Since this discussion is now in its own thread and it seems some members and interested in pursuing it, I decided to reopen it for now. Grounding and bonding are similar and related, but different. That's not always understood as well as it could be, even within the trade.

There's good opportunity for learning here. The quick exchange between tribe_fan and pcboss, in posts # 21 and 22, captures both that opportunity and the essence of that difference, IMO.

And there are plenty of related questions that could be asked.
 
  #25  
Old 12-14-12, 09:23 PM
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Tribe_fan, you got it, and a lot better and clearer that i've heard many of my "brothers" try to explain it. You're not a Sparky? Really?
 
  #26  
Old 12-14-12, 09:36 PM
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I decided to reopen it for now.
I disagree.. But that just me...


If you want to talk about GFCI an ground/bond I believe you should just talk about code and generators... That shoud explain it all, no????

http://oshaprofessor.com/Portable Ge...dards 3-05.pdf

Forget about 1950 and such.. We are talking real time .

There are so many sites that argue this interpretation that its ones own opinion on how the code is deciphered....

OK do as you wish.
 
  #27  
Old 12-14-12, 09:40 PM
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If you want to talk about GFCI an ground/bond I believe you should just talk about code and generators... That shoud explain it all, no????
Uh, no.. or at least I don't think so. GFCI is GFCI. Generators are just one of many areas where this technology has proven useful, if not critical.

Or am I missing something?
 
  #28  
Old 12-14-12, 09:47 PM
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Or am I missing something?
Yeah... I guess you did not read my link.... Dont just breeze it... Read it... And then tell me different,...
 
  #29  
Old 12-15-12, 02:17 AM
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I have to take Nashkat's side on this. The original post had NOTHING to do with connection a generator, portable or fixed, to the circuit. GFCI requirements in regard to generator installations is NOT the subject being discussed.

Short and sweet, the use of a GFCI in the context of the original post is for personnel safety. Adding an equipment grounding conductor to the circuit and connecting that equipment grounding conductor to a remote (remote from the system neutral-equipment ground-earth connection) grounding electrode in the earth does NOT add in any measurable safety over and above the GFCI.

Earlier was mentioned that a "short" would "trip" the circuit breaker in a GFCI. One of the electricians mentioned that GFCI receptacles did not have ANY such capability and I want to hammer that home. A GFCI receptacle ONLY measures the current flow on one lead and compares that to the current flow on the other lead. IF and ONLY IF that current comparison is different by a set standard, I think it is less than 6 milliamperes, does the GFCI actuate and remove the voltage from its output. GFCI receptacles never "trip" as a result of overcurrent as long as that current is balanced between the two conductors.

Mod Note: the trip level is 5 mA, commonly expressed as between 4-6 mA.

GFCIs, either receptacles or circuit breakers, are for personnel protection. A GFCI circuit breaker has, in addition to the personnel protection offered by the GFCI receptacle further protection of the circuit breaker function. A layman might make the mistake in thinking that a GFCI circuit breaker offers MORE protection but in reality the protection is simply located in two discrete packages when a standard circuit breaker is used on a circuit containing a GFCI receptacle.

I gotta stop as my mistyping is up to about a mistake for every five keystrokes.
 

Last edited by pcboss; 12-15-12 at 02:25 AM. Reason: technical
  #30  
Old 12-15-12, 08:35 AM
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OK. Good enough for me .

I found this anyway.

GFCI: Receptacles Without a Ground










 
  #31  
Old 12-15-12, 06:01 PM
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Yep. Mike Holt is always an authority worth consulting.
 
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