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Thread: To plug or not to plug into a GFCI outlet

  1. #16
    DIY Senior Member DIY's Avatar
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    Default gfci stuff

    I did not mean to start a debate about this gfci thing. The answer to my question was answered in one of the first 3 or 4 replys,but do not get me wrong i appreciate all efforts that went into replys. Now onto what i saw a few days ago. In the house i was invited to i noticed every single outlet throughout had gfci outlets..? Why? I asked the owners out of curiosity and they told me because the way the house was originally wired. All outlets boxes had only two wires running into them,so in turn they did not have a way to protect other outlets down a circuit. Interesting. Thought i'd share that bit of info. with this forum. Happy weekend to all.

  2. #17
    Homeowner Thatguy's Avatar
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    http://www.google.com/search?client=...UTF-8&oe=UTF-8

    Capacitance from motor windings to the motor shell of more than 0.09 uF will also trip these things, in addition to internal RF filters to protect electronic circuitry.

    With all the discussion about GFCIs and AFCIs, I hope these things actually save some lives, compared to not having them. I couldn't find any before and after data on this.
    With driving in a car being 30x more dangerous than electricity on a per year basis, does the NEC/UL and various elec. manuf. have this?
    http://en.wikipedia.org/wiki/Zero-risk_bias

    And watch out for
    http://www.google.com/search?client=...UTF-8&oe=UTF-8
    as far as how reliable or not these things are.
    Last edited by Thatguy; 04-11-2009 at 03:42 PM.

  3. #18
    Electrical Contractor/Instructor jwelectric's Avatar
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    Quote Originally Posted by Thatguy View Post
    Capacitance from motor windings to the motor shell of more than 0.09 uF will also trip these things, in addition to internal RF filters to protect electronic circuitry.
    This is totally untrue. Unless my math and memory has completely failed me I think that we can mathematically disprove this statement.
    The capacitive reactance of .09 microfarad would be the reciprocal of two times pi times the hertz times .09 divided into one million or somewhere around twenty nine thousand four hundred seventy three ohms. Now divide this into 120 volts and we have 4 milliamps and just under the allowable trip limit.
    Of course capacitive leak has not been allowed to be this high for well over 20 years now so although the statement holds some merit it is long outdated. Sort of reminds me of the old vacuum tubes from days gone by.

    RF filters on the secondary side of equipment power supplies we won’t even discuss as they don’t come close to fitting into this discussion.

    Quote Originally Posted by Thatguy View Post
    With all the discussion about GFCIs and AFCIs, I hope these things actually save some lives, compared to not having them. I couldn't find any before and after data on this.
    With driving in a car being 30x more dangerous than electricity on a per year basis, does the NEC/UL and various elec. manuf. have this?
    What the National Fire Protection Association and all National Testing Laboratories do have is a bad case of trying to protect the general public from the dangers arising from the use of electrical energy.
    Not many people call up and say that this GFCI device saved my life today so a different approach is taken. A count on how many people was hurt due to electrical shock and then after the codes mandates a protective device the total number of accidents should be lower if the device has any merit.
    Your comment about driving I think would be like comparing grapes to grapefruits. Take a look at the numbers when electricity was first introduced to the public. One could easily ascertain that electricity was a lot more dangerous than driving a car. It is through the continuing changing of the codes that keeps electrical energy at bay and the number of accidents and death as low as possible.

    Quote Originally Posted by Thatguy View Post
    And watch out for ----- as far as how reliable or not these things are.
    I agree and think that everyone should have a full understanding of electrical current flow if they are going to be messing around with it, wouldn’t you? All need to be assured that the advice you are receiving holds merit and not just someone copying and pasting from another discussion board.

  4. #19
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    Quote Originally Posted by jwelectric View Post
    Of course capacitive leak has not been allowed to be this high for well over 20 years now so although the statement holds some merit it is long outdated.

    What is the typical winding/shell leakage nowadays for a 1/2 hp motor? How much of the 4 mA GFCI budget does it use up?

    A count on how many people was hurt due to electrical shock and then after the codes mandates a protective device the total number of accidents should be lower if the device has any merit.
    Yes. I can't find data on this anywhere, to check if it actually made a difference.

    Take a look at the numbers when electricity was first introduced to the public. One could easily ascertain that electricity was a lot more dangerous than driving a car.
    You have numbers? Exposure to risk is certainly a factor.

    I agree and think that everyone should have a full understanding of electrical current flow if they are going to be messing around with it, wouldn’t you? All need to be assured that the advice you are receiving holds merit and not just someone copying and pasting from another discussion board.
    Nowadays the danger from elec. is down in the noise, probably for many reasons.
    1300/yr electrocuted vs. 40,000 highway deaths/yr vs. 1000/day smoking related fatalities.
    I'd look at what add'tl increment in safety you get for each dollar spent. If you say a CB gives you $20 worth of safety then an AFCI maybe gives you $1 more worth of safety. It's the law of diminishing returns.

    Do these quasi-governmental agencies mentioned above fit this description?
    "Regulatory capture is a term used to refer to situations in which a government regulatory agency created to act in the public interest instead acts in favor of the commercial or special interests that dominate in the industry or sector it is charged with regulating."

    "Public choice theory holds that capture is inevitable, because vested interests have a concentrated financial stake in the outcomes of political decisions, thus ensuring that they will find means—direct or indirect—to capture decision makers"
    Last edited by Thatguy; 04-12-2009 at 06:28 AM.

  5. #20
    Electrical Contractor/Instructor jwelectric's Avatar
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    Quote Originally Posted by Thatguy View Post
    What is the typical winding/shell leakage nowadays for a 1/2 hp motor? How much of the 4 mA GFCI budget does it use up?
    None. With today’s technology little to no current is lost through capacitive induction in the motor frame. The use of ceramic dipped windings was discontinued way back in the 60s and somewhere in the mid to late 80s it was mandated that the leakage of motors to be addressed to very low levels. I am not sure of the numbers but can find out if it would make you happy.

    Quote Originally Posted by Thatguy View Post
    Yes. I can't find data on this anywhere, to check if it actually made a difference.
    You are not looking in the right places or simply disregarding the information you are finding. The numbers are simple to find if you truly want to find them. Start with looking at the numbers that Fire Marshals have. These can be found at both state and federal levels.

    Quote Originally Posted by Thatguy View Post
    You have numbers? Exposure to risk is certainly a factor.
    In the first couple of months after the bid was released to Westinghouse for the world’s fair there was 600 deaths in the state of New York alone, but less than 10 across the nation due to automobiles for the entire year. (reference source National Fire Protection Association)

    Quote Originally Posted by Thatguy View Post
    Nowadays the danger from elec. is down in the noise, probably for many reasons.
    1300/yr electrocuted vs. 40,000 highway deaths/yr vs. 1000/day smoking related fatalities.
    I'd look at what add'tl increment in safety you get for each dollar spent. If you say a CB gives you $20 worth of safety then an AFCI maybe gives you $1 more worth of safety. It's the law of diminishing returns.

    Do these quasi-governmental agencies mentioned above fit this description?
    "Regulatory capture is a term used to refer to situations in which a government regulatory agency created to act in the public interest instead acts in favor of the commercial or special interests that dominate in the industry or sector it is charged with regulating."

    "Public choice theory holds that capture is inevitable, because vested interests have a concentrated financial stake in the outcomes of political decisions, thus ensuring that they will find means—direct or indirect—to capture decision makers"
    Spoken like a true, protect me from the thieves, murders, and rapist but don’t dare try to tell me what to do, type of cult.

    To disprove another’s thought we can use abstract comparisons to show just how low the numbers truly are. I think that you comparison is sort of like comparing the number of stars to the number of candles in a Catholic church on any given day. We must admit that the candles will light the church at night better than the stars so which is more dangerous? Can one blow out a star as easily as one can blow out a candle?

    To bring this outrageous comparison a little closer tell me just how many people are in a moving car and for how long each day. How many people light a cigarette and how many times a day? How many are coming in contact with a live electrical circuit each day? How many electrical fires are there each day?

    Now if we had as many people working with live circuits or on unprotected circuits each and every day as we have in automobiles and lighting a smoke I can guarantee that the numbers would look a lot different wouldn’t you think?
    Thank God that there is a power higher than our self to mandate some sort of safety. Can you imagine the chaos we would have on our streets if there were no highway patrol to enforce the laws or even worse if there were no traffic law set in place at all?

  6. #21
    Homeowner Thatguy's Avatar
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    Quote Originally Posted by jwelectric View Post
    but can find out if it would make you happy.
    Happier, yes. . .

  7. #22
    Computer Programmer Bill Arden's Avatar
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    Quote Originally Posted by jwelectric View Post
    The capacitive reactance of .09 microfarad would be the reciprocal of two times pi times the hertz times .09 divided into one million or somewhere around twenty nine thousand four hundred seventy three ohms. Now divide this into 120 volts and we have 4 milliamps and just under the allowable trip limit.
    You are not taking harmonic noise into account. The power line voltage waveform is not a sine wave and the extra frequency's add to the current.

    And then there is the long range power utility communication systems. These can add quite a bit of noise spikes. The worst is the DCSI TWACS system (90 amp pulses at the house), then there is the cannon EMETCON(9Khz to 12Khs) and the L&G TS2 system(560Hz).

    All these can add quite a bit of current and that is why the Capacitor & diode power supplys have a series resistor to limit the current from higher frequencys.
    Important note – I don’t know man made laws, just laws of physics
    Disclaimer: I'm a big fan of Darwin awards.

  8. #23
    Electrical Contractor/Instructor jwelectric's Avatar
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    Quote Originally Posted by Bill Arden View Post
    You are not taking harmonic noise into account. The power line voltage waveform is not a sine wave and the extra frequency's add to the current.
    Boy we sure made a big jump here from a MOV to the power company’s grid and the harmonics found on that grid.
    The important part of this is the fact that we are not affected by the primary harmonic currents of the power grid. The transformer at our house only steps down voltage and not current. The amount of current draw at our homes is solely based on the loads we have not how much current the primary lines are carrying.

    Quote Originally Posted by Bill Arden View Post
    And then there is the long range power utility communication systems. These can add quite a bit of noise spikes. The worst is the DCSI TWACS system (90 amp pulses at the house), then there is the cannon EMETCON(9Khz to 12Khs) and the L&G TS2 system(560Hz).
    Once again not on the circuits in our homes. The TWACS system is a software system that was designed by Distribution Control Systems, Inc. (DCSI), a subsidiary of ESCO Technologies Inc. and is mostly used as a load control program to ensure the end customer always has power.
    The newer version NG 3.0 can often times detect a grid outage and reset the breaker before the homeowner knows the power was out. It can detect this so fast that a lot of electronic clocks never stop working such as the clock on microwaves.

    Quote Originally Posted by Bill Arden View Post
    All these can add quite a bit of current and that is why the Capacitor & diode power supplys have a series resistor to limit the current from higher frequencys.
    Again Brother Bill the amount of current on the primary lines of the utility company in no way affects the current on a 120 volt branch circuit that is protected by a GFCI device in our homes. The harmonics on the utility primary power lines does not enter our homes either. These harmonics are lost at the step down transformer that supplies our homes.

  9. #24
    Senior Robin Hood Guy Ian Gills's Avatar
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    I have a GFCI on my sump pump and it has never tripped by accident.

    Similarly I have a GFCI on my condensate pump.

    Each life can be valued at about US$2 million. To protect me and those around me, these are a pretty good investment.

    All within 6 feet of water source.
    Last edited by Ian Gills; 04-14-2009 at 09:29 AM.

  10. #25
    Computer Programmer Bill Arden's Avatar
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    Quote Originally Posted by jwelectric View Post
    Boy we sure made a big jump here from a MOV to the power company’s grid and the harmonics found on that grid.
    1. When you draw currents from a outlet that WILL affect the voltage since the transformer has both resistance and inductance. The higher the frequency the less current you need to change the voltage. At 10Khz it does not take much current to change the voltage.

    2. the DCSI TWACS system includes a AMR(Automatic meter reader) component and that meas that it includes a module that mounts inside the house electric meter. That unit uses a Triac to pull 90 amps just before the zero crossing. These pulses of current can cause problems and is part of the reason the AMR part of the system has been banned from some states.

    3. There is a "voltage noise test" that units have to pass and that is probably why the 0.09 uF value was stated. It's not that 0.09 uF will trip a GFCI, but that it MIGHT trip a GFCI.
    Important note – I don’t know man made laws, just laws of physics
    Disclaimer: I'm a big fan of Darwin awards.

  11. #26
    Homeowner Thatguy's Avatar
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    .09 uF @ 60 Hz is 30kΩ, 120v/30kΩ = 4 mA, which is just about the trip threshold for a GFCI.
    ROMEX® has about 100 pF/ft, so 900' of ROMEX® should trip a GFCI.
    Last edited by Terry; 12-07-2011 at 10:22 AM.

  12. #27
    Electrical Contractor/Instructor jwelectric's Avatar
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    Quote Originally Posted by Bill Arden View Post
    1. When you draw currents from a outlet that WILL affect the voltage since the transformer has both resistance and inductance. The higher the frequency the less current you need to change the voltage. At 10Khz it does not take much current to change the voltage.

    2. the DCSI TWACS system includes a AMR(Automatic meter reader) component and that meas that it includes a module that mounts inside the house electric meter. That unit uses a Triac to pull 90 amps just before the zero crossing. These pulses of current can cause problems and is part of the reason the AMR part of the system has been banned from some states.

    3. There is a "voltage noise test" that units have to pass and that is probably why the 0.09 uF value was stated. It's not that 0.09 uF will trip a GFCI, but that it MIGHT trip a GFCI.
    Bill I know that you are trying hard but the simple answer is none of this will affect a GFCI.

    If other than the 60 Hz sine wave would affect a GFCI then there would never be a listing on items such as the X10 control systems sold to control lights throughout a home. These devices send signals across the electrical wires that are different than the 60 Hz sine of the voltage being controlled.

    The automated meter readers you have referred to in your post is connected in parallel with the home so any currents or harmonics introduced by this item would end at the point of use and not be transmitted into the home.

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