Power cable

Discussion in 'Audio Hardware' started by Orbe, Oct 5, 2020.

  1. Ingenieur

    Ingenieur Forum Resident

    for reference
     
  2. bgiliberti

    bgiliberti Will You Be My Neighbor?

    Location:
    USA
    Metric sucks too! Take that!
     
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  3. Ingenieur

    Ingenieur Forum Resident

    Is it 240 to ground/neutral or line to line with each line 120 to ground neutral?
    Your plug has 3 prongs: is one hot, one neutral/return and one ground?
     
  4. head_unit

    head_unit Forum Resident

    Location:
    Los Angeles CA USA
    I don't know what you mean by shell game. As for comparison, the Yamaha was good but old, the Onkyo I forget the model number offhand but it's like a 3-year old 2x100 that seems well regarded. Or do you mean the Denon and the Parts Express? I do not agree they are pieces of **** they are what they are. What do YOU think is not a "piece of ****"?!?

    The PE sounds pleasant at low volumes, it's life is playing classical music through small speakers in an office my wife is working remotely in. The Denon was $1300, and while everyone "knows" AVRs construction is not as state of the art as more expensive stuff, that does not mean all AVRs sound bad at the moderate levels they are generally used. Let me say as a scientist that an awful lot of opinions about sound, THAT is often rather "BS", because it is almost NEVER based on true single-independent-variable comparisons but rather on psychological bias and expectations, and conclusions based on sonic memory which is notoriously fallibe. Part of the point of the PE vs Denon comparison is exactly that we felt uncertainly about our impressions of the sound we were listening to perhaps just a half hour before. Some bitchers about fast double blind comparisons complain that you cannot develop listening impressions so fast, yet I never hear of anyone engaging in long-term blind tests either.

    By the way, surely not having heard either the Denon or the PE, you are frankly not entitled to any opinion whatsoever about how they sound, are you?
     
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  5. Ingenieur

    Ingenieur Forum Resident

  6. MGW

    MGW Less travelling, more listening

    Location:
    Scotland, UK
    Yes. As I understand it, 220 to 240V to ground, at least in the UK.
     
    Ingenieur likes this.
  7. MGW

    MGW Less travelling, more listening

    Location:
    Scotland, UK
    I'm sure this makes some form of sense to you. But, you are wrong about metric. It is the simplest system and almost any everyday calculation involving units and conversions can be done in the head.
     
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  8. elvisizer

    elvisizer Forum Resident

    Location:
    San Jose
  9. jea48

    jea48 Forum Resident

    Location:
    Midwest, USA


    jea48 said:
    Not sure why you chose this example. "But if the fault is to 'earth' it uses the ground electrode."
    To what end? Electrical safety? Please explain.
    Ingenieur response:
    Because it is the only path, safety and to ensure tripping of the protective device.

    It may be the only path. But it will not cause the tripping of the "protective device".

    Don't take my word. Your post #55.

    My response:
    You are kidding right? You think what we are discussing now directly relates to the OP's thread?


    My response:
    Yes. But it's not considered an effective ground fault path. It will not trip the breaker in the panel. It will become an added load to the branch circuit and be reflected on the power bill.


    My response:
    The utility power transformer is an isolation transformer. It's the source for the discussion. The split phase secondary winding is an SDS.


    My response:
    Building steel, (as defined by the NEC connected to earth), shall be bonded to the electrical service Grounded conductor, per the NEC. A hot ungrounded conductor ground fault to bonded steel will trip the OCPD. You are changing the subject of our discussion.

    I've never seen a concrete encased electrode on a single family dwelling
    My response:
    You might want to brush up on your NEC. NEC 250.50, 250.52, and 250.52 (3)
    My state has required an CEE since, I believe around 2009-2012.
    Now as you know the AHJ has the final say. It may not be required in your state, county, or city.

    My resonse:
    "Unless the next door neighbor is on a separate xmfr,"
    The POCO in my area is MidAmerican Energy. Not that it should matter. The high voltage grounded conductor is bonded to the transformer's secondary grounded conductor and connected to earth at every transformer. Therefore the ground fault current still finds it way from the neighbors grounding electrode system>> to the electrical service Grounded Conductor >> POCO power line >> to the transformer high volt bonded grounded conductor >> to the secondary bonded grounded conductor, and the high voltage grounded conductor extends to the transformer that feeds the house where the 120V circuit originated. So there is a closed circuit path to the transformer in question. Now things might be done different in your state.

    My response:
    Yes. Residential electrical contractors use the NEC. NEC is bare minimum electrical safety standards. Unless the builder specs otherwise the NEC is used. Note the AHJ has the final say.

    My response:
    Yes, I know what you meant. Do you think the average audiophile following what you posted did? Maybe, maybe not. It is clear now though.:)

    Response:
    That's why the NEC requires that receptacles outlets installed outdoors shall be GFCI protected. NEC even requires the minimum required locations they are required for a residential dwelling unit. At least the AHJ does in my area.
    Your example of the what if a bare hot conductor in the hand to out the bare feet is exactly why the NEC requires GFCI protection for outdoor receptacle outlets.

    My response:
    Please stay on point. Your whole premise of your posts is for an outside driven ground rod ground being an effective ground fault path back to the electrical panel grounded conductor. It is not.

    My reponse:
    Step potential. For a pet, in the front or back paws and out the other. Current passes through the pet's body.
    For a human through one foot through the growing down and out the other foot. Would that kill a person? Sure hurt like hell! That part wouldn't but when the person passed out and their body fell on the ground where would the step potential entry and exit points to the earth be? Could that kill the person? Yeah.
    Understanding Step and Touch Potential

    My reponse:
    Agree. I misread this post. My apologies.
    .

    My reposnse:
    You can have ungrounded systems, we use them all the time,
    Yeah, in healthcare facilities. OR rooms, MRI procedure room, CATH Lab procedure room, ER treatment rooms, ICU and CCU patient rooms.

    Other places. Soybean mill prep processing and soybean oil extraction plant. Aluminum processing foundries and I am sure there are others. One place an 'Isolated Power System' is not allowed, per the NEC, is in a residential dwelling unit.

    My response:
    The purpose for the System Ground as defined by the NEC.

    The Building Equipment Grounding System is design for connecting equipment as defined by the NEC to the Grounded conductor and System Ground, for years called Grounding Electrode System by the NEC.
    For the electrical wiring of a building if a hot to equipment ground fault event occurs the system ground is not at play. The EGC carries the ground fault current back to the service equipment grounded conductor. The ground fault current becomes part of the branch circuit OCPD connected load. IF the ground fault is just leakage and not a bolted fault OCPD just sees it as the connected load. If the leakage ground fault current plus the normal connected on the current carrying conductors of the circuit exceeds the breaker handle rating the breaker hopefully will trip open. A bolted ground fault event should trip the breaker pretty quick.
    (Note: Above is for non protected GFCI, or AFCI, or combination AFCI/GFCI protected branch circuits)
    .
     
    Last edited: Oct 14, 2020
  10. MGW

    MGW Less travelling, more listening

    Location:
    Scotland, UK
    Must be the fabled, non-existent US sense of humour!
     
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  11. jea48

    jea48 Forum Resident

    Location:
    Midwest, USA
    EDIT:


    That should read the earth connection of the System Ground is not at play.
    The EGC carries the ground fault current back to the service equipment grounded conductor.
     
  12. elvisizer

    elvisizer Forum Resident

    Location:
    San Jose
    Dunno, I got it <shrug>
     
  13. Jimi Floyd

    Jimi Floyd Forum Resident

    Location:
    Pisa, Italy
    You replaced a faulty power cable with a functional one. The new one works. Where is the news?

    [​IMG]
     
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  14. Dave

    Dave Esoteric Audio Research Specialist™

    Location:
    Greater Vancouver
    :hide: I can hear differences in power cables.

    Just for fun today I hauled out the old Black Sand Silver Reference cable I had been using to power my former Classé Seventy power amp. After getting the Perreaux PMF 1150B which doesn't allow after market cords I just removed it. I had felt something was amiss with my sound so I connected the Silver Reference cable to the SCD-1 just to check it out. It is a considerable difference over the SCD-1 stock cord. Much better low mid-range and bass response with considerably more full spectrum realistic detail. As always YMMV.
     
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  15. bgiliberti

    bgiliberti Will You Be My Neighbor?

    Location:
    USA
    Someday I will learn to use smileys even when I would have thought it was obvious I was being facetious.
    Take that! ;)
     
  16. Tullman

    Tullman Senior Member

    Location:
    Boston MA
    There are what they are pieces of ****. Ok, they make music and they certainly are many levels above the cell phone, but this is lo-fi. Why don't you compare the "giant killer" Parts Express to a Pass amp? I don't know how you can expect some big difference between amps that are lo-fi.
     
  17. Ingenieur

    Ingenieur Forum Resident

    jea48 said:
    It may be the only path. But it will not cause the tripping of the "protective device".
    sure it will, my house has 3 electrodes: 2 rods, utility rod, water pipe: when I measured it varied between 2-4 Ohms depending on season: 120/5 ~ 24 A, it will trip a 20 A CB

    Don't take my word. Your post #55.
    You miss the whole picture
    the rods
    the water main
    possible building structure
    utility ground rod at xfm
    butt coil at pole
    these parallel electrodes will give you a very low R, the rod alone is < 25 Ohm (or 2 rods which will be on the order of 10-15 alone)


    You are kidding right? You think what we are discussing now directly relates to the OP's thread?
    No comment

    Yes. But it's not considered an effective ground fault path. It will not trip the breaker in the panel. It will become an added load to the branch circuit and be reflected on the power bill.
    Yes it will, that is one reason why they do it, as proven above. So a ground current < 20 A flowing at 120 V will not cause heat? At the point of the fault, wire to metal stud, you will have a lot of heat, and eventually fire, that is why they ensure it trips.

    The utility power transformer is an isolation transformer. It's the source for the discussion. The split phase secondary winding is an SDS.
    No it is not, it supplies the fault power from the primary and hence the generator.

    Building steel, (as defined by the NEC connected to earth), shall be bonded to the electrical service Grounded conductor, per the NEC. A hot ungrounded conductor ground fault to bonded steel will trip the OCPD. You are changing the subject of our discussion.
    Most homes are wood or steel on concrete, that is not required to be bonded.

    You might want to brush up on your NEC. NEC 250.50, 250.52, and 250.52 (3)
    My state has required an CEE since, I believe around 2009-2012.
    Now as you know the AHJ has the final say. It may not be required in your state, county, or city
    What State? It is allowable, not required. Not used on single family dwellings.

    The POCO in my area is MidAmerican Energy. Not that it should matter. The high voltage grounded conductor is bonded to the transformer's secondary grounded conductor and connected to earth at every transformer. Therefore the ground fault current still finds it way from the neighbors grounding electrode system>> to the electrical service Grounded Conductor >> POCO power line >> to the transformer high volt bonded grounded conductor >> to the secondary bonded grounded conductor, and the high voltage grounded conductor extends to the transformer that feeds the house where the 120V circuit originated. So there is a closed circuit path to the transformer in question. Now things might be done different in your state.
    Again, parallel paths

    Yes. Residential electrical contractors use the NEC. NEC is bare minimum electrical safety standards. Unless the builder specs otherwise the NEC is used. Note the AHJ has the final say.
    I am a PE and electrical Inspector. I only have final say as long as it does not conflict with the NEC, Code in force, I can't dream stuff up.

    Yes, I know what you meant. Do you think the average audiophile following what you posted did? Maybe, maybe not. It is clear now though.:)
    I am not sure based on your google based understanding

    That's why the NEC requires that receptacles outlets installed outdoors shall be GFCI protected. NEC even requires the minimum required locations they are required for a residential dwelling unit. At least the AHJ does in my area.
    Your example of the what if a bare hot conductor in the hand to out the bare feet is exactly why the NEC requires GFCI protection for outdoor receptacle outlets.
    Captain Obvious


    Please stay on point. Your whole premise of your posts is for an outside driven ground rod ground being an effective ground fault path back to the electrical panel grounded conductor. It is not.
    I will do as I please

    Step potential. For a pet, in the front or back paws and out the other. Current passes through the pet's body.
    For a human through one foot through the growing down and out the other foot. Would that kill a person? Sure hurt like hell! That part wouldn't but when the person passed out and their body fell on the ground where would the step potential entry and exit points to the earth be? Could that kill the person? Yeah.
    I design substation ground beds, step and touch potential is key. On some we paint arrows so folks stand on a gradient line instead of across them..
    You did not understand what I wrote.


    Agree. I misread this post. My apologies.
    No comment

    Yeah, in healthcare facilities. OR rooms, MRI procedure room, CATH Lab procedure room, ER treatment rooms, ICU and CCU patient rooms.
    Healthcare systems are grounded (isolated some times). Entire NEC section on it. Industrial facilities use ungrounded delta.

    Other places. Soybean mill prep processing and soybean oil extraction plant. Aluminum processing foundries and I am sure there are others. One place an 'Isolated Power System' is not allowed, per the NEC, is in a residential dwelling unit.
    An isolated system is NOT an ungrounded system.

    The purpose for the System Ground as defined by the NEC.
    The Building Equipment Grounding System is design for connecting equipment as defined by the NEC to the Grounded conductor and System Ground, for years called Grounding Electrode System by the NEC.
    For the electrical wiring of a building if a hot to equipment ground fault event occurs the system ground is not at play. The EGC carries the ground fault current back to the service equipment grounded conductor. The ground fault current becomes part of the branch circuit OCPD connected load. IF the ground fault is just leakage and not a bolted fault OCPD just sees it as the connected load. If the leakage ground fault current plus the normal connected on the current carrying conductors of the circuit exceeds the breaker handle rating the breaker hopefully will trip open. A bolted ground fault event should trip the breaker pretty quick.
    (Note: Above is for non protected GFCI, or AFCI, or combination AFCI/GFCI protected branch circuits)

    Not true: a line (hot) can contact a frame and if sitting on the floor (refrigerator) some fault WILL travel thru the ground rod, inversely proportional to their Z,
    If for some reason the EGC is open ALL will travel thru the rod.

    .
     
    Last edited: Oct 14, 2020
  18. Uglyversal

    Uglyversal Forum Resident

    Location:
    Sydney
    With all due respect on this subject there are some variables you are not taking into account and it helps to keep an open mind..

    1) Nothing is necessarily right or wrong but depending on the color of the glass you are looking through, people's opinions could be different.

    2) There is what could be an educated guess, that has direct correlation with what I've said in (1). That applies particularly if the person making the guess has had plenty of exposure to a great deal equipment, good and bad.

    What's somebody else's garbage could be someone else's treasure and vice versa.
     
  19. MGW

    MGW Less travelling, more listening

    Location:
    Scotland, UK
    Precisely my point ... now where are the emojis for tumbleweed and "Squeal like a little piggy, boy!"
     
  20. samurai

    samurai "See the glory, of the royal scam."

    Location:
    MINNESOTA
    No one can tell you what you hear or what you like.
    So it's great that you've found a PC you like. Enjoy!
     
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  21. jea48

    jea48 Forum Resident

    Location:
    Midwest, USA
    Ingenieur post #92
    My response.
    2017 NEC 250.50
    250.50 Grounding Electrode System. All grounding electrodes as described in 250.52(A)(1) through (A)(7) that are present at each building or structure served shall be bonded together to form the grounding electrode system.

    Exception: Concrete-encased electrodes of existing buildings or structures shall not be required to be part of the grounding electrode system when the steel reinforcing bars or rods are not accessible for use without disturbing the concrete

    There it is. Per the NEC for new construction. Been that way for years.

    //

    Ingenieur Post #75
    jea48 said:
    Note:
    (We have been using ground rods for the Grounding Electrode in our exchanges.) As you know there may two other electrodes found in a residential dwelling. Metal potable incoming water line and possibly a Concrete Encased Electrode, commonly called a ufer ground. Per the NEC they shall be all connected together and then be connected to the service entrance neutral grounded conductor. The connected together electrodes are considered one grounding electrode per the NEC. For this post I will continue using ground rods for the earth electrode.)

    Ingenieur response:
    Obviously, and the structure it self if constructed of steel...I've never seen a concrete encased electrode on a single family dwelling.


    Ingenieur Post #92
    Ingenieur post #75
    Your words.
    " Obviously, and the structure it self if constructed of steel..."

    My post was in response to yours.
    And how did you respond?
    "Most homes are wood or steel on concrete, that is not required to be bonded."

    //

    Ingenieur Post #92
    NO response....

    //

    Ingenieur post #92
    "the rod alone is < 25 Ohm (or 2 rods which will be on the order of 10-15 alone)"

    My response:
    Unless the rod(s) to soil resistance was tested the actual resistance is unknown. Only one rod is required by NEC IF the resistance is less than 25 ohms. The only way to know is to test it. Hell it might test 100 ohms. Drive another rod. NEC is satisfied. No testing required. If tested after driving the second rod the resistance may only have dropped 50 ohms. Who cares? NEC was satisfied when the second rod was installed.

    "the water main"
    Maybe plastic, not metal.

    "possible building structure"
    House, more than likely wood framing structure.
    Or maybe cement block with stucco exterior finish as is typical in the southern an southwestern states.

    Again, there may be variables for the average rod to soil resistance around the country.

    //

    Ingenieur post #92
    My response:
    Context.

    jea48 post #84:
    Ingenieur said:
    jea48 said;
    If the fault is to mother earth there would be a closed circuit for the ground fault current to return to the source. A low impedance path? Hardly. It also adds stray voltage to the earth. Will it cause a regular T-M breaker to open? Now a GFCI breaker should trip due to the imbalance in the hot and neutral currents in the sensing unit. But not from a short circuit or overload condition.
    Ingenieur said:
    Obviously, but the fault current still returns to source thru the ground rod (or plumbing bond, etc.)

    My response:
    Yes. But it's not considered an effective ground fault path. It will not trip the breaker in the panel. It will become an added load to the branch circuit and be reflected on the power bill.

    //

    Ingenieur post #92
    My response:
    "and an electrical inspector"....
    Of what? For who?
    State government?
    County government?
    City government?
    Private contracting firm? Certified by who?

    Ingenieur post #92
    Ingenieur said:
    "I only have final say as long as it does not conflict with the NEC, Code in force, I can't dream stuff up."

    My response:
    The NEC does not on its own have any enforcement power. Enforcement of the NEC is through State Laws, and or City and County ordinances. The AHJ (Authority Having Jurisdiction) is a government governing body. In my State 'The State Electrical Examining Board' decides when to adopt the new edition of the NEC. The State has the power to approve all of the NEC if they so choose or they can pick and chose what they want to amend as the State board sees fit. The 2020 NEC will not be adopted in my State until January 1 of 2021. Until then the State is still working under the 2017 NEC.


    Here is the electrical code for Chicago IL.
    Chicago Construction Codes
    Click on:
    Chicago Electrical Code (Title 14E)
    (full text read only)

    Go to page #5

    Quote:
    "(IMPORTANT NOTICE REGARDING 2018 Edition CHICAGO ELECTRICAL CODE
    Based on the 2017 NATIONAL ELECTRICAL CODE)"

    Note this:

    Quote:
    "It contains amendments (both additions and deletions) to 2017 edition of NATIONAL ELECTRICAL CODE."

    You can view the changes made by the AHJ, City Of Chicago governing electrical board.
    Shaded grey text are the changes.

    //

    Response from my post #84
    Ingenieur post #92
    My response.
    Sorry, I though you would understand I was speaking of the ac power feeding receptacle outlets in OR rooms, MRI procedure room, CATH Lab procedure room, ER treatment rooms, ICU and CCU patient rooms used for electronic monitoring equipment and such that is connected by wires to a patient.

    Ingenieur said:
    Healthcare systems are grounded (isolated some times). Entire NEC section on it.
    Yeah, I know quite well. Article 517.

    Response from my post #84
    Ingenieur post #92
    My response:
    2017 NEC
    Article 517
    Healthcare Facilities

    517.2 Definitions.
    Isolated Power Systems.
    A system comprising an isolation transformer or its equivalent, a line monitor, and its ungrounded circuit conductors.

    517.2 Definitions.
    Isolation Transformer
    A transformer of multi-winding type, with the primary and secondary winding physically separated that inductively couples its ungrounded secondaries winding(s) to the grounded feeder system that energizes its primary winding(s).

    Secondary winding legs, leads, are floating above ground. No reference potential to ground whats so ever.

    //

    Finally this:

    Ingenieur post #55
    My response:

    "A conductor shorts to ground, metal stud, etc."

    "If it has to return to the panel thru the ground rod only
    "

    Say what?
    "metal stud, ect".
    As in an interior metal stud wall?
    In the event of a hot ungrounded conductor shorting to a metal stud of the wall, the ground fault current will somehow find its way outside of the building structure to mother earth and somehow find its way to the earth driven ground rod....


    .
     
    Last edited: Oct 15, 2020
  22. Ingenieur

    Ingenieur Forum Resident

    You cut and paste but have no true education or knowledge of the subject imho.

    soil has resistivity not resistance in the context you used it.
    R = p L/A

    I am a government employee, I supervise inspectors, sign off on their work and perform them. I am also a QEI and the ahj.
    My primary function is acting as the PE electrical safety engineer/manager for a state law enforcement bureau.
    I have 25 years private sector consulting experience designing power systems plus 8 in government. A PE for 30 years in 1/2 dozen states, both in power and controls (seperate tests).

    The AHJ in many locals is a private contractor approved (not appointed) by a government body, but not a government employee.
    I served as the appointed PE for numerous bodies and managed that process.

    I also have a small (me lol) private engineering firm and do side work (authorized by my employer).
    Commercial & residential inspector
    C & R plans review
    But mostly I do design.
    Also hold a Class A water and wastewater license
    I've been around...in the world...not the internet, and unfortunately (because I love to learn, got my grad cert in power engineering at 50, my MSEE at 40) you have nothing to teach me, but I did you if your ego had allowed it.

    It is obvious you really have no true understanding of the subject (not meant as an insult, but as an observation) and your onslaught began with 'correcting' me claiming I said drive separate rods not bonded to the service system, which was wrong.

    Why do they bond:
    Water pipe
    Steel in footers
    Building steel
    If they will never carry fault current?

    I am also on state electrical equipment task force and unfortunately investigate electrical fatalities.
    Also serve on a national code writing body.

    Why do class 2/3 data centers require (or at least comply with ANSI guidance) a 5 Ohm bed and class 4 a 3? Usually both are <2 Ohm.
    Does it have anything to do with lower emi/rfi for sensitive electronic equipment?

    peace, I'm out, it's become a waste of time, but please do not proffer electrical engineering advice
    Thanks
     
  23. jea48

    jea48 Forum Resident

    Location:
    Midwest, USA
    Sure it was meant as an insult...You started you insults in the last few posts. You'll notice I didn't respond to them though, until now. Now because you apparently feel threatened you have resorted to personally attacking my character.
    Why? Maybe because I have proven time after time you've been wrong in many of the things you have posted. I notice you didn't respond to those posts in my previous post#97.

    As for my qualifications, it shouldn't matter beings I was the one proving you were wrong time after time. What I have seen time after time is you repeatedly using your "Appeal to authority" for how you must be right and I am wrong. Man your arm really has to be sore from patting yourself on the back as often as you have.

    For others that may be reading this post I am a retired State Licensed Master Class A Electrician. I have over 40+ years of practical hands on experience working in the electrical commercial and industrial industry. I was responsible for designing and layout for many design build electrical projects during my 40+ years working in the trade. Though retired, I have kept my Master's License up to date.

    //

    Ingenieur Said: Post #97.
    Where in any of my posts did I say that a bonded metal water pipe or bonded building steel "will never carry fault current"? They are inside the building structure. The are bonded to the service grounded conductor. The metal incoming water pipe by a grounding electrode conductor and building steel (meeting NEC as an electrode) by a bonding grounding conductor.

    Though "Steel in Footers" could be a stretch.

    Though below grade, basement concrete floor, (especially if damp), I could see where the concrete floor is somewhat bonded to the concrete footing CEE. Especially where the walls are poured concrete. It still, imo, would not be considered a good low impedance EGC ground fault current path.

    //

    My beef with you is you continue to tell the readers on this thread that a ground fault that takes place inside a building where there is not an EGC present if a ground faulted hot conductor came into contact with a non grounded metal stud wall, somehow, someway, the fault current magically will find its way outside of the building structure, find its way to mother earth and then travel through the earth to the earthed ground rod. And through all that enough fault current will flow causing the branch circuit breaker to overload and trip open. Come on Guys, surely you don't believe that crap.

    //

    "A conductor shorts to ground, metal stud, etc."

    Ingenieur post #92

    Metal stud. As in a wall in a building built using metal studs.
    So Ingenieur has said if the EGC (Equipment Grounding Conductor) connection to the metal electrical outlet box is broken and IF the Hot conductor were to come into contact with a metal stud the ground fault current will flow to outside the building, flow through the earth to the ground rod and then flow to the service equipment grounded conductor, (main service grounded neutral conductor). Causing the branch circuit breaker to trip open. (From His post #92 above.)

    Build that wall.
    First thing is to eliminate the chance any other branch circuits that may feeding an outlet on Ingenieur's imaginary wall. If another branch circuit is feeding another outlet on another location of the metal stud wall, (Could be another room Wall. Walls are tied together), then the branch circuit EGC would carry the fault current back to the electrical panel equipment ground bar and cause the branch circuit breaker to trip open.

    So lets build a metal stud wall in the center of a room. Pick a spot, on say, the second floor of an office building. Imagine the wall as an island. It just sets there all by itself. The bottom metal track plate fastens wall to the floor. The bottom track plate is the only connection to the building space.No connection of any kind above the wall.

    Now lets install an electrical outlet steel box to one of the metal studs on the wall.

    Options to electrically feed the outlet box
    Branch circuit wiring in EMT conduit.
    MC (Metal Clad) cable.
    AC (Armored Cable).

    Pick which ever one you like. Now intentionally, break, open, the ECG. EGC is no longer connected to the electrical outlet box or mechanically/electrically connected to the metal studs.
    Circuit conductors are still intact and circuit is energized.
    Touch the hot conductor to the metal stud the steel electrical box is fastened to. (Be sure to turn your head so your face and eyes will be protected... Face shield if you got it).
    Well, what will happen?... Nothing! No sparks a flying? How can that be? Where are the sparks?

    The steel electrical box is no longer grounded by the EGC and therefore neither is the metal stud wall.
    Now if the hot was left touching the metal stud the wall would be HOT, Live, Energized. HOT with reference to a grounded object. But what about the outdoors ground rod thingy?

    .
     
    Last edited: Oct 16, 2020 at 8:52 PM
  24. tubesandvinyl

    tubesandvinyl Forum Resident

    I'll never remove my Tchernov power cords from my system!!
    Amazing stuff.
     
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  25. Ingenieur

    Ingenieur Forum Resident

    "My beef with you is you continue to tell the readers on this thread that a ground fault that takes place inside a building where there is not an EGC present if a ground faulted hot conductor came into contact with a non grounded metal stud wall, somehow, someway, the fault current magically will find its way outside of the building structure, find its way to mother earth and then travel through the earth to the earthed ground rod. And through all that enough fault current will flow causing the branch circuit breaker to overload and trip open. Come on Guys, surely you don't believe that crap."

    I never said that it was isolated. Fastened to the footer, it will flow back thru the ground rod.
    How much? Depended on the path Z. If a perfect insulator or isolated the frame would rise to the fault V....until someone touched it, THEN thru the body, concrete earth, rod.

    By your logic no need for GFCI since there is no chance of I flow thru the body to earth/rod.

    That only applies to an ungrounded delta (or wye but seldom used, delta common).
    A phase can go to frame/ground, 995 vac, a person can grab it, no shock.
    Until another phase faults to frame/ground then phase-phase is imparted.

    I investigated an fatal accident: a phase went to frame on a machine, another phase went to frame on a different machine, EGC busted on one. Poor soul climbing thru the machinery troubleshooting touched the frames with the open EGC. He was grounded.
    If both EGC's were intact a ph-ph fault would have resulted and tripped the CB.
    He became the EGC on the machine with the broken one.
    Tragic
     

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