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  1. #1
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    Default G.F.C.I. on a 2 wire system?

    Is there a way to install a GFCI breaker on a 2 wire system and have 2 prong outlets changed to 3 prong outlets?

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    Default Re: G.F.C.I. on a 2 wire system?

    Sure. Install gfci and label receptacle "not grounded".

    The above statements are expressed solely as my opinion and in all probability will conflict with someone else's.
    Stu, Fredericksburg VA

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    Default Re: G.F.C.I. on a 2 wire system?

    Thanks... I have heard that this method could be used. This is the first time i have ran into it. It still dont seem right though....


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    Default Re: G.F.C.I. on a 2 wire system?

    Quote Originally Posted by James Norman View Post
    Is there a way to install a GFCI breaker on a 2 wire system and have 2 prong outlets changed to 3 prong outlets?
    I belive that GFCI protection was originally invented for ungrounded systems as a method to offer ground fault protection without a grounding system being in place!

    As for going the GFCI breaker route, I'm not sure a modern GFCI breaker will work. I know that the manufacturers made some changes a few years back to the GFCI breakers and they no longer fit some of the older panel designs. You might need to go with GFCI protected outlets.

    Last edited by Scott Patterson; 09-26-2011 at 03:00 PM.
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    Default Re: G.F.C.I. on a 2 wire system?

    GFCI's are an acceptable way to provide protection on ungrounded systems. The GFCI's do not need a ground to be functional. They measure minute differences between the hot and neutral currents. If a certain difference is recognized, it "assumes" a leak I.E. ground fault and trips the circuit.


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    Default Re: G.F.C.I. on a 2 wire system?

    Yes they can be installed without a ground, and will trip. As mentioned above, mark the outlet "not grounded," and be careful what you use it for. You can damage certain devices.

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    Default Re: G.F.C.I. on a 2 wire system?

    I believe the code-required labeling phrase is "GFCI Protected, No Equipment Ground".

    Depending on the jurisdiction the mere act of replacing the receptacle in a now GFCI protection required location will require GFCI protection being installed. Depending on the jurisdiction (adoption of whichever code cycle and depending on amendments to language contained therein) It may further require the use of TR, WR (or both) type receptacles, and if in a location currently requiring AFCI protection, the same.

    If the equipment is not compatable with more modern GFCI type breakers, the combination GFCI receptacle or a GFCI deadfront might be employed to provide protection load side.

    Extension of the existing "two-wire" circuit most likely would not be permitted, certainly not without "special permission".

    Of course this presumes the "two-wire" system to which you refer, is not in fact a three-wire type circuit using a wiring method employing other than a "wire" as an EGC, such as bonded EMT for example, a perfectly legal method then and now of providing EGC using other than a "wire" as a conductor for equipment grounding.

    Last edited by H.G. Watson, Sr.; 09-26-2011 at 05:52 PM. Reason: typo in "code"

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    Default Re: G.F.C.I. on a 2 wire system?

    Also keep in mind that a GFCI breaker monitors cumulative ground fault leakage on the entire circuit and that every component, appliance, etc., of the circuit which may contribute a negligible amount of ground fault current can, for the cumulative sensing GFCI breaker, cause the GFCI breaker to trip when no individual component or appliance would cause a local GFCI receptacle outlet to trip.

    Let's say that there are 3 appliances on the circuit, and each appliance has a ground fault leakage of 1.5 ma, that would not trip a GFCI receptacle outlet, but the 3 appliances together would, should at 4.5 ma, trip a GFCI breaker protecting the entire circuit.

    A GFCI receptacle out is local in the sense that it only monitors the current flowing through the GFCI receptacle outlet and whatever is plugged into that GFCI receptacle outlet.

    Many, dare I say most, electricians and builders do not consider that aspect when they install one GFCI and protect 3-4-5 or more receptacle outlets downstream from it. Then the GFCI starts tripping and they cannot figure out what is wrong - because nothing is wrong.

    Don't get me wrong, the appliances should not have 1.5 ma of ground fault leakage, but that would not be enough to require the GFCI to shut power off for the safety of the user.

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    Default Re: G.F.C.I. on a 2 wire system?

    Also the test button on the small three indicator light plug in outlet testers will not trip a GFCI installed in an ungrounded system.

    Galen L. Beasley
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    Housing Authority of Kansas City MO

  10. #10
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    Default Re: G.F.C.I. on a 2 wire system?

    Is there a section of the code that addresses this?


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    Default Re: G.F.C.I. on a 2 wire system?

    Quote Originally Posted by James Norman View Post
    Is there a section of the code that addresses this?
    Addresses which part of this?

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    Default Re: G.F.C.I. on a 2 wire system?

    Quote Originally Posted by James Norman View Post
    Is there a section of the code that addresses this?
    406.3(D)(3)(c).

    You're still not allowed to plug in a three-prong cord cap into them, (250.114) hence the "GFCI protected, No Equipment Ground" required labeling (and that includes those silly little three-light testers).

    Last edited by H.G. Watson, Sr.; 09-27-2011 at 05:56 PM.

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    Default Re: G.F.C.I. on a 2 wire system?

    Quote Originally Posted by Galen L. Beasley View Post
    Also the test button on the small three indicator light plug in outlet testers will not trip a GFCI installed in an ungrounded system.

    Yes, its good to be aware of this. I've had it confuse me on more than one occasion. I had about to call out a problem that really did not exist. It was just the nature of the beast thing and I caught myself before the final report went out.


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    Default Re: G.F.C.I. on a 2 wire system?

    Quote Originally Posted by Galen L. Beasley View Post
    Also the test button on the small three indicator light plug in outlet testers will not trip a GFCI installed in an ungrounded system.
    The GFCI test button on the $300 SureTest and other expensive testers will also not trip a GFCI on an ungrounded system - they all NEED to have that ground to create the ground fault effect they are trying to create.

    As I have said many times before ... *the best* GFCI tester is *the TEST button* on the GFCI device you are trying to test - that test button does not require a ground in order to test the GFCI ground fault function.

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  15. #15
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    Default Re: G.F.C.I. on a 2 wire system?

    I just want to add a common misconception that gfci on 2 wire systems protects you from shock. GFCI does not protect you from shock but it will ,all things correct, protect you from electrocution. Lets say you have a faulty 3 wire power cord with some bare wire showing that happens to be the ungrounded conductor (hot conductor) and that power cord is plugged into a gfci installed on a 2 wire system with no equipment ground. If you come in contact with that bare spot with your hand for example current will flow thru you trying to seek its source. The gfci will 'see' that current in the black wire but will not see it in the grounded conductor aka neutral. The gfci will trip given that the milliamps are outside the trip threshold of the gfci receptacle .. usually 5 or 6 ma. You may however feel a slight shock before the gfci trips and removes power from the appliance with the faulty cord. You will however be saved from a fatal electrocution.
    Second thing I want to add is a gfci breaker IMO is better safety overall. A gfci breaker monitors the entire branch circuit whereas a gfci receptacle only monitors what is plugged into it or its protected outlets.


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    Default Re: G.F.C.I. on a 2 wire system?

    Quote Originally Posted by H.G. Watson, Sr. View Post
    406.3(D)(3)(c).

    You're still not allowed to plug in a three-prong cord cap into them, (250.114) hence the "GFCI protected, No Equipment Ground" required labeling (and that includes those silly little three-light testers).
    H. G.-
    I thought that the "No Equipment Ground" label was to alert people that a ground (required for surge protectors to function properly) was not available.
    I have advised clients that it is perfectly all right to plug anything else in, whether it's a "two-prong or three prong" (I speak "plain english" to clients) as long as it doesn't require surge suppression, the GFCI will protect them, their children and their pets from electrocution, which, as I understand it, was the original idea behind the grounded plug and receptacle.
    Have I been wrong to say a three-prong is ok?

    Last edited by bruce audretsch; 09-27-2011 at 11:06 PM.
    Bruce M Audretsch

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    Default Re: G.F.C.I. on a 2 wire system?

    Bruce, from Article 250. You will see that certain equipment needs to be grounded.

    250.114 Equipment Connected by Cord and Plug. Under
    any of the conditions described in 250.114(1) through (4),
    exposed, normally non–current-carrying metal parts of
    cord-and-plug-connected equipment shall be connected to
    the equipment grounding conductor.
    Exception: Listed tools, listed appliances, and listed equipment
    covered in 250.114(2) through (4) shall not be required
    to be connected to an equipment grounding conductor where
    protected by a system of double insulation or its equivalent.
    Double insulated equipment shall be distinctively marked.
    (1) In hazardous (classified) locations (see Articles 500
    through 517)
    (2) Where operated at over 150 volts to ground
    Exception No. 1: Motors, where guarded, shall not be required
    to be connected to an equipment grounding conductor.
    Exception No. 2: Metal frames of electrically heated appliances,
    exempted by special permission, shall not be required
    to be connected to an equipment grounding conductor,
    in which case the frames shall be permanently and
    effectively insulated from ground.
    (3) In residential occupancies:
    a. Refrigerators, freezers, and air conditioners
    b. Clothes-washing, clothes-drying, dish-washing machines;
    ranges; kitchen waste disposers; information
    technology equipment; sump pumps and electrical
    aquarium equipment
    c. Hand-held motor-operated tools, stationary and
    fixed motor-operated tools, and light industrial
    motor-operated tools
    d. Motor-operated appliances of the following types:
    hedge clippers, lawn mowers, snow blowers, and
    wet scrubbers
    e. Portable handlamps
    (4) In other than residential occupancies:
    a. Refrigerators, freezers, and air conditioners
    b. Clothes-washing, clothes-drying, dish-washing machines;
    information technology equipment; sump
    pumps and electrical aquarium equipment
    c. Hand-held motor-operated tools, stationary and
    fixed motor-operated tools, and light industrial
    motor-operated tools
    d. Motor-operated appliances of the following types:
    hedge clippers, lawn mowers, snow blowers, and
    wet scrubbers
    e. Portable handlamps
    f. Cord-and-plug-connected appliances used in damp or
    wet locations or by persons standing on the ground or
    on metal floors or working inside of metal tanks or
    boilers
    g. Tools likely to be used in wet or conductive locations
    Exception: Tools and portable handlamps likely to be used
    in wet or conductive locations shall not be required to be
    connected to an equipment grounding conductor where
    supplied through an isolating transformer with an ungrounded
    secondary of not over 50 volts.

    All answers based on unamended National Electrical codes.

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    Default Re: G.F.C.I. on a 2 wire system?

    Quote Originally Posted by bruce audretsch View Post
    H. G.-
    I thought that the "No Equipment Ground" label was to alert people that a ground (required for surge protectors to function properly) was not available.
    I have advised clients that it is perfectly all right to plug anything else in, whether it's a "two-prong or three prong" (I speak "plain english" to clients) as long as it doesn't require surge suppression, the GFCI will protect them, their children and their pets from electrocution, which, as I understand it, was the original idea behind the grounded plug and receptacle.
    Have I been wrong to say a three-prong is ok?
    Almost all electronic equipment produce and are affected by radio frequency's.
    Electronic equipment has a shield to keep the radio waves in and to keep other radio waves out. The shield is grounded to bleed off the radio waves. So not having a ground connected can cause problems with that piece of equipment and even other equipment nearby. Having a GFCI will protect someone from being shocked, but does not protect the equipment.

    ' correct a wise man and you gain a friend... correct a fool and he'll bloody your nose'.

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    Default Re: G.F.C.I. on a 2 wire system?

    Quote Originally Posted by Roger Frazee View Post
    Second thing I want to add is a gfci breaker IMO is better safety overall. A gfci breaker monitors the entire branch circuit whereas a gfci receptacle only monitors what is plugged into it or its protected outlets.
    I agree with a point of exception, and that point of exception being when there is enough leakage over the entire circuit and all appliances plugged into the receptacles protected by that circuit that the cumulative ground fault current is sufficient to trip the GFCI in the breaker.

    After an electrician (or maybe just a well meaning homeowner) checks everything in the circuit and finds that nothing in the circuit should be tripping that GFCI breaker - they may very well remove that GFCI breaker and replace it with another one, which also trips and must be 'bad', after trying a couple of different 'bad' GFCI breakers, they install a regular (non-GFCI) breaker. Now there is no GFCI protection, and it was done in good faith with good intentions, because there is nothing on that circuit which should be tripping the GFCI.

    The person doing that does not consider that the breaker is 'seeing' the cumulative leakage, and, they are correct, 'there is nothing on that circuit which should be tripping the GFCI' -however, the many leakages which, individually, will not trip the GFCI will trip the GFCI when added together back at the circuit source ... the GFCI breaker.

    In that sense, and for that reason, I feel that GFCI receptacle outlet devices offer better protection because they will not be deemed as 'bad' when they really are not 'bad', they are doing their job (just like the GFCI breaker is doing its job based on the cumulative leakage).

    Anyway, that if my opinion and why.

    Jerry Peck, Construction / Litigation Consultant
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    Default Re: G.F.C.I. on a 2 wire system?

    Quote Originally Posted by Jerry Peck View Post
    I agree with a point of exception, and that point of exception being when there is enough leakage over the entire circuit and all appliances plugged into the receptacles protected by that circuit that the cumulative ground fault current is sufficient to trip the GFCI in the breaker.

    After an electrician (or maybe just a well meaning homeowner) checks everything in the circuit and finds that nothing in the circuit should be tripping that GFCI breaker - they may very well remove that GFCI breaker and replace it with another one, which also trips and must be 'bad', after trying a couple of different 'bad' GFCI breakers, they install a regular (non-GFCI) breaker. Now there is no GFCI protection, and it was done in good faith with good intentions, because there is nothing on that circuit which should be tripping the GFCI.

    The person doing that does not consider that the breaker is 'seeing' the cumulative leakage, and, they are correct, 'there is nothing on that circuit which should be tripping the GFCI' -however, the many leakages which, individually, will not trip the GFCI will trip the GFCI when added together back at the circuit source ... the GFCI breaker.

    In that sense, and for that reason, I feel that GFCI receptacle outlet devices offer better protection because they will not be deemed as 'bad' when they really are not 'bad', they are doing their job (just like the GFCI breaker is doing its job based on the cumulative leakage).

    Anyway, that if my opinion and why.
    Good point

    ' correct a wise man and you gain a friend... correct a fool and he'll bloody your nose'.

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    Default Re: G.F.C.I. on a 2 wire system?

    For those who are interested the GFCI was developed by Charles Dalziel and patented in 1965.

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  22. #22
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    Default Re: G.F.C.I. on a 2 wire system?

    Jerry

    That's a good point and I certainly have seen home owners take out gfci's and replace with typical circuit breakers because they don't believe the gfci is seeing a fault but rather is just another gimmick that results in false trips.

    I've been out of the trade now for some time and I don't recall any gfci breakers tripping from cumulative current leakage on a residential branch circuit. However, I am sure you have or you would not be suggesting the problem. That would certainly be a concern. I think what I worry about is the line side fault to a metal box that will not clear when a gfci receptacle is used....metal faceplates and screws etc.


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    Default Re: G.F.C.I. on a 2 wire system?

    Quote Originally Posted by Roger Frazee View Post
    I think what I worry about is the line side fault to a metal box that will not clear when a gfci receptacle is used....metal faceplates and screws etc.
    One would hope that a line side fault would trip the breaker ... provided there is a ground path back ... ... which could certainly be a concern on an ungrounded circuit.

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  24. #24
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    Default Re: G.F.C.I. on a 2 wire system?

    Quote Originally Posted by Jerry Peck View Post
    One would hope that a line side fault would trip the breaker ... provided there is a ground path back ... ... which could certainly be a concern on an ungrounded circuit.
    Yep that is what I was trying to say...


  25. #25
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    Default Re: G.F.C.I. on a 2 wire system?

    Quote Originally Posted by James Norman View Post
    Is there a way to install a GFCI breaker on a 2 wire system and have 2 prong outlets changed to 3 prong outlets?
    Install one in electrical panel


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    Default Re: G.F.C.I. on a 2 wire system?

    Zibby,

    There one and only one way to change a two wire receptacle into a three wire receptacle and meet the safety conditions of the Code.

    That is to re-do the entire circuit from the panel through the end of the circuit with a cable that has the grounded conductor, the ungrounded conductor and the egc in it. You also must install grounded receptacles on this circuit. Period, that's it!

    Merely connecting a GFCI Breaker into the panelboard, does not change the wiring configuration one tiny bit. However it does mandate that each of the receptacles on this circuit now be labeled to indicate that there is no ground present on the receptacle.

    Don


  27. #27
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    Default Re: G.F.C.I. on a 2 wire system?

    Quote Originally Posted by Donald Farrell View Post
    Zibby,

    There one and only one way to change a two wire receptacle into a three wire receptacle and meet the safety conditions of the Code.

    That is to re-do the entire circuit from the panel through the end of the circuit with a cable that has the grounded conductor, the ungrounded conductor and the egc in it. You also must install grounded receptacles on this circuit. Period, that's it!

    Merely connecting a GFCI Breaker into the panelboard, does not change the wiring configuration one tiny bit. However it does mandate that each of the receptacles on this circuit now be labeled to indicate that there is no ground present on the receptacle.

    Don
    Not true. GFCI outlet needs ground wire, as it is using it as reference to see current flow difference. It measures current flow in hot and neutral side. and if there is more than 5mA difference it will disconnect them. Now if you outlet doesn't have ground wire, then your only option is to install GFCI breaker inside panel. GFCI breaker has extra white wire that you connect to neutral bus, and your hot and neutral wires connect directly into GFCI breaker. Its the same Idea as connecting more outlets into GFCI outlet.

    If you don't install GFCI breaker, then I would still recommend to label each outlet "not grounded"


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    Default Re: G.F.C.I. on a 2 wire system?

    Zibby, a GFI, breaker or receptacle, does not need a grounding wire for proper operation.

    GFI receptacles can be installed in the device box on a two wire system. Although this is not easy due to the amount of room the older conductors take up in the boxes it is a code compliant method and allows three prong devices to be installed downstream.

    The NEC also requires the downstream to be labeled "No Equipment Ground".

    All answers based on unamended National Electrical codes.

  29. #29
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    Default Re: G.F.C.I. on a 2 wire system?

    Quote Originally Posted by Jim Port View Post
    Zibby, a GFI, breaker or receptacle, does not need a grounding wire for proper operation.

    GFI receptacles can be installed in the device box on a two wire system. Although this is not easy due to the amount of room the older conductors take up in the boxes it is a code compliant method and allows three prong devices to be installed downstream.

    The NEC also requires the downstream to be labeled "No Equipment Ground".
    You are right.


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    Default Re: G.F.C.I. on a 2 wire system?

    If utilizing a combination GFCI receptacle, IT TOO must be labeled "GFCI protected, No Equipment Ground", not just the protected, load side, grounded type receptacles installed thereafter.

    Quote Originally Posted by bruce audretsch
    H. G.-
    I thought that the "No Equipment Ground" label was to alert people that a ground (required for surge protectors to function properly) was not available.
    I have advised clients that it is perfectly all right to plug anything else in, whether it's a "two-prong or three prong" (I speak "plain english" to clients) as long as it doesn't require surge suppression, the GFCI will protect them, their children and their pets from electrocution, which, as I understand it, was the original idea behind the grounded plug and receptacle.
    Have I been wrong to say a three-prong is ok?

    bruce audretsch,

    Yes you have been wrong to say it was "ok" to do so. It is and has been WRONG to utilize a grounding cord cap (3-"prong") equipped device or appliance for any device in any receptacle which is not provided with equipment grounding. Double insulated appliances are not equipped with 3-"prong" cord caps.

    Example - two such devices both plugged in. Irrespective of power supply/circuit breakers a multitude of applicances are configured with devices which can store and discharge energy, including start capacitors, etc. and utilize case ground which must be solidly grounded to protect the user (and property).

    GFCI circuit breakers and combination devices open (interrupt) only the HOT conductor path - NOT the groundED conductor path (unlike for example a combination GFCI cordset designed to be used outdoors); therefore they only stop the supply of electricity from the service when tripped - they do not "disconnect" the device(s), such as those containing motors, etc.. which are inappropriately "connected" to the electrical system (plugged in to grounding type receptacles which are not provided with a sufficient equipment grounding path - "unplugging" the appliances does that, not necessarily safe to do so while energized, even when not, especially while in contact with a device case, control, or conductive surface.

    3-wire solidly grounded receptacles have been required in laundry areas since the late 40s IIRC (first residential area required).

    Last edited by H.G. Watson, Sr.; 10-04-2011 at 08:09 AM.

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