Nuisance Current Blocker

Abstract

The Nuisance Current Blocker (NCB) is a unique protective device that utilizes resistors, gas discharge tube arrestors and choke/inductors to block low level current on equipment grounding conductors while maintaining an effective ground fault path to quickly activate overcurrent protective devices. EPRI reported that 60% of the electric grid's primary return current travels back through the earth. The NEC addresses this “Objectionable Current” in Section 250.6 and provides options to remediate in (B)(3) with “Interrupt the continuity of the conductor . . . ” or (B)(4) “Take other suitable remedial and approved action” and also in 250.6(E). Residential grounding systems have no protection against primary return current. The NCB blocks this ground current from entering the home via well pumps, also reduces ground loops, magnetic fields, chokes high frequencies, and reduces contact current exposures on grounding mats, sheets, and RF shielding paint to prevent, according to the EPRI, potential cancer causing environments.

Claims

1. A current blocking device that prevents low level current from entering a home or an electrical circuit or a grounded object; enables fault level voltages and current to pass quickly in order to effectively activate overcurrent protection devices.

2. The current blocking device of claim 1 can be used to block “foreign” current sources like NEV or stray voltage, sourced from primary side transformer grid current where no protection in homes exists at this time.

3. The current blocking device of claim 1 further comprising a choke/inductor that helps trap 3 kHz and above frequencies from entering the home on the grounding conductor circuit.

4. The current blocking device of claim 1 wherein the device is positioned to isolate certain bonds or appliance parts so current loops eliminated, yet preserves fault protection.

5. The current blocking device of claim 1 is used to reduce electric field charge build up by draining away excessive capacitive voltages from conductive materials and objects.

6. The current blocking device of claim 1 is used to provide a healthier environment by preventing harmful contact current exposures from shielded walls, grounding mats and other grounded objects and surfaces.

7. The current blocking device of claim 1 reduces magnetic fields from current flows on grounding systems.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0082] The disclosure can be understood with reference to the following figures. The components in the figures are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the disclosure. Moreover, in the figures, like reference numerals designate corresponding parts throughout the different views.

[0083] FIG. 1 is the basic diagram with its most essential components, without switches or any additional add-on features.

[0084] FIG. 2 shows the placement of the NCB for in-door applications. It is showed in-series between a receptacle outlet 210 and a grounded bed sheet 211 or a grounding mat 212.

[0085] FIG. 3 describes the placement in-series between an outside grounded appliance, for instance well pump 321, and a main service disconnect panel 311 grounding bus bar 310.

DETAILED DESCRIPTION

[0086] The presently disclosed subject matter is described with specificity to meet statutory requirements. However, the description itself is not intended to limit the scope of this patent. Rather, the inventor has contemplated that the claimed subject matter might also be embodied in other ways, to include different steps or elements similar to the ones described in this document, in conjunction with other present or future technologies. Figures can allow various steps unless and except when the order of individual steps is explicitly described.

[0087] FIG. 1 is the core circuit diagram and embodiment of the protective apparatus before adding any embellishments or additional components to compliment the different applications. The choke/inductor is 103. Resistor 104 (or set of resistors) can be set from 1000-1,000,000 ohms. The GDT 105 (or pair of GDTs) will activate at about 60V, 120V or 470V, depending upon the application.

[0088] In FIG. 1, the unprotected path 101 will ideally be attached to incoming current and frequencies. The protected outgoing path 102 would be ideally connected to a protected device.

[0089] In FIG. 1, 60 Hz current entering the unprotected path 101 will meet at least 10,000,000 ohms of resistance from the GDT 105 and take the alternate path through the choke/inductor 103. Higher than 700 Hz frequencies will be increasingly trapped by 190 mH choke/inductor 103 as the cut-off zone is around 3 kHz. Those below 700 Hz, especially 60 Hz electricity of common households, will continue through to meet resistor 104. Depending upon the ohms of resistor 104, either no or only limited micro-amp levels of current will be allowed through to the protected side 102.

[0090] In FIG. 1, if voltages rise to more than 60V, indicating a ground fault, the GDT 105 path quickly activates to be a low impedance path for current. This is designed to quickly trip a breaker should the protected line 102 makes contact with a live wire. The best hope we have for fault protection and against electrocution is the fast acting trip design of a circuit breaker.

[0091] FIG. 2 shows an indoor embodiment to protect a person using a grounding mat 212 connected to 202, from the harmful nuisance current and frequencies entering in from the AC receptacle outlet 210. The NCB connects at 201 to a line 209 and plugs into receptacle outlet 210. The NCB also protects the grounding sheets 211 from the equipment grounding conductor current in outlet 210. Not pictured are the connectors, the box housing, or switches for testing purposes.

[0092] In FIG. 2, starting at the receptacle outlet 210, the unprotected line 209 which has low level current and DE frequencies, connects to the NCB's unprotected point 201. The current will then take the path of least resistance, towards the choke/inductor 203.

[0093] The GDT 205 has about 10 million ohms of resistance and resistor 204 has less, anywhere from 1000 to 1,000,000 ohms, depending upon the embodiment of the device. All current and frequencies below a certain level will be blocked from traveling on either path, by resistor 204 or GDT 205.

[0094] Frequencies will be absorbed by the choke/inductor 203 from oscillating, and depending on the current level, the milli-amp levels of current are blocked by both resistor 205 and the GDT 205. Should either the grounding sheets or mat come in contact with a live/energized source of phase current from that circuit, the GDT 205 will activate (at a certain fault level voltage like 60 VAC) and current will flow back through 201, 209 to 210 and back to trip the breaker (overcurrent protection device) and shut off the source energizing that circuit.

[0095] Variations include multiple GDT configured in parallel set for differing voltages, one to activate around 60 VAC and the other around 110 VAC. This provides additional resilience, security and longevity to the device and increases efficacy of the breaker under differing fault conditions.

[0096] A ground fault can happen from making direct contact with the 120 VAC phase conductor or from the neutral/grounded conductor, both are at least 60 VAC, as it makes a parallel path with the equipment grounding conductor. As there will never be an ideal condition of zero impedance on the fault return path, fault voltages will most likely be higher than 60 VAC, or half the phase voltage (typically between 115-120 VAC).

[0097] The GDT 205 is designed to trip a breaker, quickly.

[0098] Resistor 204, depending upon its rating, will allow electric fields that have built up a capacitive charge upon bodies, to dissipate slowly. This is a very key element to grounding mats as they were being sold to lower excessive body voltage.

[0099] Resistor 204 will not lower body voltage to zero as some existing grounding mats will do when tested with a body voltage meter or multimeter, to the equipment grounding conductor.

[0100] FIG. 3 addresses appliances 321 that make a direct connection to the earth 320, outside the home. This application is designed to stop earth current 340, existing from either primary return current or secondary side of the transformer sources. And we need to be protected from an open neutral condition or a fault from a neighbor's residence sharing the same transformer (secondary side transformer current). Anything plugged into the earth has the potential to be a conductor for these “foreign” current sources.

[0101] FIG. 3 shows the NCB installed in-series on the equipment grounding conductor 322 between a well pump 321, and main panel 311, terminated on bus bar 310, through equipment grounding conductor 312, as one example. The primary return current 340 will seek a path back to source on the grounded metallic components through 320 of the well 321, that are connected to the equipment grounding conductor 322, and travel into the home wiring through grounding bus bar 310, if the NCB were not applied to block it.

[0102] To interrupt the continuity of that circuit, as provided by NEC 250.6(B)(3), the NCB connects 301 to the equipment grounding conductor 322 of the outside appliance 321. The protected side 302 connects through conductor 312 to the panel equipment grounding bus bar 310, or neutral bus, depending upon the location of the appliance breaker.

[0103] One of skill in the art will appreciate that the choke/inductor 303 could alternatively be placed on the side of the unprotected source, and resistor 304 absorbing the resulting current and frequencies on the protected side, the home side, though, either direction (302 to 301) will work to block current.

[0104] Typical appliances that invite primary side transformer current into the home grounding system are: well pumps, basement sump pumps, flood drain grinders, circuits from underground bunkers, cable internet lines, and phone line bonds. The public has other readily available solutions to block the cable internet sheath current, water and gas pipe bond current and they should be utilized first.

[0105] Addressing appliances that have an equipment grounding conductor is the focus here, not their bonds. Equipment grounding conductors 209 or 312 facilitate clearing a fault quickly within a breaker panel 311, through the neutral/ground connection 310. Bonds between metallic objects serve purposes intended for lightning strike surges by creating an equipotential plane or to facilitate a path to earth. Unfortunately, bonds become a part of the problem as they create loops in the grounding system and adds a path the earth that delays the efficacy of an overcurrent device. The NCB can be effectively utilized to remove ground loops on bonding systems.

[0106] Blocking foreign current on the cable internet coax is best done with a ground loop isolator. The water and drain pipes can have PVC or food grade PEX inserted to interrupt their continuity. Gas lines can have dielectric unions inserted to stop that foreign current or loops.

[0107] To maintain the equipment grounding conductor's performance, the NCB can be installed in-series with the appliance, on the equipment grounding conductor, to stop the nuisance foreign current and loop current yet provide essential ground fault protection. The same for sump pumps, flood drain grinders or any metallic appliance making contact with the soil or concrete and rebar that brings in primary grid current flows to the home grounding system.

[0108] The question must be asked, does this bond only serve as a lightning path to earth or is it to trip a breaker? We don't want both as NEC 250.4(A)(5) clearly specifies: “The earth shall not be considered as an effective ground-fault current path.” The GDT should not allow lightning to enter a wiring premises, only leave to go to earth. Bonds and devices specifically for lightning should be rated for lightning, above 240V, or they will corrupt the home grounding system. Otherwise, we will have increased current on grounding conductors throughout the wiring premises.

[0109] Additional Components

[0110] One embodiment includes the use of a buzzer, an alarm indicating high voltage or current condition.

[0111] Another embodiment includes a switch to access resistor settings of different magnitudes.

[0112] Another embodiment includes a switch for different gas discharge tube voltage activation levels.

[0113] Another embodiment includes an on/off switch for the entire unit to quickly assess levels with and without an active NCB.

[0114] Another embodiment includes a voltage readout display.

[0115] Another embodiment includes Banana plug insert adapters to accommodate existing grounding mats and grounded bed sheet product lines.

[0116] Another embodiment includes alligator clips to adhere to a surface or conductor.

[0117] Another embodiment will be a master test box that has all of the components in one so a Building Biologist can carry one master NCB around to test all the variables, before and after, for each application.

[0118] Alternative Applications

[0119] One of skill in the art will recognize that some of the alternative implementations set forth above are not universally mutually exclusive and that in some cases additional implementations can be created that employ aspects of two or more of the variations described above. Likewise, the present disclosure is not limited to the specific examples or particular embodiments provided to promote understanding of the various teachings of the present disclosure. Moreover, the scope of the claims which follow covers the range of variations, modifications, and substitutes for the components described herein as would be known to those of skill in the art.

[0120] Where methods and/or events described above indicate certain events and/or procedures occurring in a certain order, the ordering of certain events and/or procedures may be modified. Additionally, certain events and/or procedures may be performed concurrently in a parallel process when possible, as well as performed sequentially as described above.

[0121] The legal limitations of the scope of the claimed invention are set forth in the claims that follow and extend to cover their legal equivalents. Those unfamiliar with the legal tests for equivalency should consult a person registered to practice before the patent authority which granted this patent such as the United States Patent and Trademark Office or its counterpart.

[0122] Phone Bonds

[0123] The bond wire from the phone line grounding bus is connected to the grounding electrode conductor. It is also connected back to the transformer's ground and neutral connection. It is prime source for lightning and grid surges to enter the home's grounding system. Home faults should not go to earth, or get dispersed in multiple paths throughout the neighborhood, so this phone bond requires a higher than 240V GDT, and suggest 470V. Lightning will surely have more than household fault current and voltages and it is beneficial to them separate.

[0124] Shielding Paint

[0125] If the home has had shielding paint installed and is being grounded to an outdoor, secondary or auxiliary grounding electrode, this raises an interesting dilemma. It is fairly easy to block foreign current sources. Those outside grounding connections are not associated with any indoor overcurrent protection devices. Just add resistance and diode of an adequate size to that line and that blocks the foreign current. But Radio Frequency (RF) shielding paint is in very close proximity to indoor circuits and wiring in the walls. The potential is high (nearly impossible to avoid) for the indoor electric fields to be attracted to the outside grounding path to return to source. The inverse is true as well. The exterior sources of primary current will find a way into the home to return to the substation. An area of capacitance will be created on and between the two systems, the outdoor secondary grounded shielding paint and the indoor grounded wiring in the walls. The resulting electric field and the frequencies contained therein is a problem.

[0126] The NEC says “electrically conductive materials” (and shielding paint is certainly electrically conductive) “shall be connected together . . . ” Section 250.4(A)(4): Bonding of Electrically Conducted Materials and Other Equipment. “Normally non-current carrying electrically conductive materials that are likely to become energized shall be connected together and to the electrical supply source in a manner that establishes an effective ground fault current path.”

[0127] The potential for lightning to arc from one material to the other is possible and can create a fire. Bonding them together limits the voltage difference between systems. So the NEC preferred choice reverts back to eliminating the outside auxiliary grounding electrode and merging the two systems into one, grounded in one place with the house electrical system. That brings up the problem of dirty electricity sourced from the home wiring and appliances being broadcast out from the surfaces of the shielding paint out into the sleeping area. Both are a predicament and have clear problems, either way. It is best to avoid this conundrum and use nonconductive, ungrounded RF shielding fabrics and turn the power off to the bedroom so there are no electric fields.

[0128] If this is not possible, adding the NCB to the grounding system of the shielding paint could more closely satisfy the spirit of the code requirements and additionally reduce the electric field/dirty electricity contamination of the shielded walls. Of course, the indoor sources of current and electric fields must be dealt with as much as possible, in either case. It is highly recommended (a rule) to de-energize the conductors inside the walls to limit the capacitive effects and inductive properties between the wiring and shielding paint. Next best is using Metal Clad (MC) cable or armored cable which does a good job of containing the indoor sources of electric fields if the home has been thoroughly mitigated of its electrical neutral/ground code violations. MC will not prevent a lightning surge arc between 2 separate grounding systems.

[0129] Eliminating Ground Loops Between Appliances and Panels

[0130] Another appliance based problem deals with small DC transformers grounded inside of AC units and air handlers. There is often 20-50 mA of current on the coolant line and the equipment grounding conductors associated with those systems. The handler or AC condenser unit DC transformer should not be electrically connected to the frame. In addition, often the AC unit will be powered from the main disconnect panel, outside where the neutral is earthed, and the coolant line is connected to the air handler, inside, powered from a subpanel. This creates a loop on the grounding system and the coolant line between the units. Short of moving the AC unit to the subpanel along with the Air handler, there is no solution for removing that current loop from the equipment grounding conductor. The NCB can be used to stop the circulation of current on that equipment grounding conductor/system yet preserve its fault clearing capabilities.

[0131] Diode to Keep Out Lightning Surges

[0132] Another embodiment of the NCB integrates a diode in series with the GDT and choke/inductor. Should lightning energy surge towards the home, the energy would travel out to the secondary grounding electrode and help dissipate the surge. Should lightning strike nearby on the property, the surge would be blocked and not travel up the grounding conductor into the shielding paint and into the home. There is no accommodation for a direct hit from lightning. The GDT voltage would be established above household voltages (470V) as to not interfere with proper functioning of the 120V or 240V circuit breakers. Too many paths on the grounding system delays or prevents the action of the overcurrent protective device and we certainly don't want the earth to be a part of the fault clearing process as NEC 250.4(A)(5) clearly specifies: “The earth shall not be considered as an effective ground-fault current path.”

[0133] Equipotential Grids and Swimming Pools

[0134] Swimming pools have large equipotential grid rebar systems that will bring in primary current from the earth and into the home through the pool subpanel equipment grounding conductor. The best way to remove the hazard is by removing all lights or appliances that make contact with the water or even come near to the water and cutting the wires that come to the pool lights to ensure they can never conduct electricity or will ever need a breaker for protection. Then all that is remaining is the pool equipment bonded to the equipotential pool grid. The NCB can then be used to stop the circulation of earth current between the outside grid and the pool equipment. The pool equipment needs to have a hard connection to the breakers to trip quickly should there be a problem inside the equipment.

[0135] In the pool water, always test to confirm there are very low levels of voltage (<2 mV) and current (<2 μA) between the water and the rail support handles or anything else a person might touch while entering the pool. Making the pool water the same voltage as the electric grid is not a sound solution towards preventing harm. An equipotential grid still has current running through it. And, under fault conditions, the current and voltage conditions in an equipotential plane will exceed an acceptable NEC fire code standard. The principal of reducing the voltage difference between two points with bonding to achieve a healthy standard has been shown to be a faulty premise in Equipotential Planes, a Figment of the Imagination by Forensic Electrical Engineer Donald W. Zipse. [ieeexplore.ieee.org/document/1677287]

[0136] Zipse: “If the public wants to be able to enter a swimming pool or a hot tub or to take a shower without the fear of receiving an unwanted electric shock or to be a victim of an electrocution, then the public must rise up in letter writing to their Public Service Commissions and their legislators both local and federal and demand an electrical distribution system free from to flow of uncontrolled hazardous stray current.” [ieeexplore.ieee.org/document/1242596]

[0137] GEC 1/0 to Compensate for the Change in Grounding

[0138] Oversizing the Grounding Electrode Conductor (GEC) may be essential after installing the NCB because the NCB will remove parallel paths to earth. The service neutral is struggling to begin with and is one of the biggest reasons inspiring the need for the NCB invention in the first place. The Neutral cannot handle all the harmonics and loads so that over-current is being pushed into the earth and our grounding system. If we remove these multiple paths to earth, the pressure will be concentrated back on the neutral conductor and back up into the home grounding system and that could mean higher electric and/or magnetic fields throughout the home. Oversizing the GEC helps relieve this pressure on the home equipment grounding conductor system. This has been proven, before and after, with a NFA 1000 9-point bed map diagnostic. [homeemftracing.com/shop/ols/products/10-gec-confirmation-nfa-9-point]

[0139] It is also essential to establish only one neutral-to-earth connection per residence, at the meter, and not at the main distribution breaker panel. Ensuring a meter/disconnect combo has no appliance breakers in that panel will reduce the amount of “foreign” primary return current circulating through the home wiring. [homeemftracing.com/shop/ols/products/meter-disconnect-installation-notes]

[0140] After the electrician removes all the code violations that put current onto the equipment grounding conductors, the NCB can be used to remove the remaining current.