67 to 1. True. Abstract Many factors must be considered when designing the electrical system for critical facilities, especially the type of ground system used. Perhaps it was intended to be connected to a transformer. • Ground fault sensing is undefined for the grounded phase, so typically cannot be used at locations where GF is required, such as healthcare facilities Figure 2. Dies geschieht unabhängig von der Erdung der Stromquelle. My attached schematic is a center tapped phase (this creates a neutral point in secondary side of bank that can be tied to ground). There is of course the resistance-grounded wye, if needed, for industrial. J. I have seen highly trained electricians freak out at a corner grounded delta in a power plant by me. 5869 posts · Joined 2009. Could be as jraef mentioned. Corysan said: 240V 3ph corner grounded delta will definitely yield: A-Grd: 240V. It is quite common as a separately derived system for 230 volt equipment in a plant with a 480 volt service. The service is a corner grounded 240V delta. Its corner ground Delta 3 phase , 208 V , 30 horsepower. A corner grounded power system is a system that is fed from a delta transformer winding with one phase grounded. 120 V, single-phase, 2 W, solidly grounded II. This type of grounded system is 3-phase, delta-connected and is called a corner-grounded system, because one corner of the delta is grounded (figure 1). The grounded phase is a "grounded conductor" that carries current. NEC actually calls it the "grounded conductor" which would seem to open up the possibility of corner grounding one of the three phase conductors. The primary can be grounded wye, ungrounded wye or delta while the. The grounded leg is no more dangerous than the grounded neutral leg in a 120 volt circuit. I know right now there is a customer that is served by the POCO with ungrounded wye primary - corner ground 480 volt delta secondary, three transformers totaling 1000kVA. Have to physically see the MBJ to. rbulsara (Electrical) 16 Jun 05 20:28. Remote Operation (MN/MX Voltage Release) Let-Through Curves and Trip Curves. grounded TN systems (TN-S systems) 1 Corner-grounded and midpoint-grounded delta systems 2 (< 600 V) IT systems (ungrounded or high-resistance-grounded [>30 ohms]) 3 R10, R11 Do not remove EMC AC or VAR. 7. The others will be your expected phase to phase voltage to eachother and ground. Location: In the bothy, 7 chains down the line from Dodman's Lane level crossing, in the nation formerly known as Great Britain. You are now operating on a corner grounded delta unintentionally. Use dedicated IES files on product website for non-standard CCTs. i agree. 480V. Nov 24, 2010 #1. That is a corner-grounded delta system. Why would a corner grounded Delta system have a 4 wire drop? SDG&E?s Service Standards book states: ? On overhead service installations the service ground conductor, provided as the redundant 4th wire corner ground conductor of a 480 volt delta service, will be connected to the customer?s identified equipment grounding conductor at. For a red leg delta with one winding center tapped and grounded at the center tap, yes. Two phase-ground voltages = 480V and one phase-ground. 44. Menu. They have 3 phase delta 480. For me, its a textbook corner grounded delta. . Besoeker3 Senior Member. 22 does not apply to the B phase of a center tapped 120/240 volt delta system. We have an old system in our plant that is the grounded B phase or the corner grounded delta. On a 240V 3 phase grounded delta system, the voltage to ground is 240V from 2 of the poles. Aside from serving the step-down transformer, the 480V side is mostly going unused. I guess what I'm saying is that Delta seems never to be a good option. Equivalently what happens when the corner of the delta is grounded is that the voltage at each phase is offset by the same AC voltage (i. 12). When electrical systems or equipment are grounded, the ground (earth) is part of the electrical circuit. g. not smaller than the required grounding electrodeCorner grounded Delta. Wye-wyes are extremely rare in <600V systems. By doing so, we are creating a split phase supply as well as a three-phase delta connected supply. This Wikipedia article explains TT, IT and TN-S power distribution systems. Location. D325NT, D325NTR, D326NT, D326NTR, T327N and T327NR accept only 300Vac Class T fuses. Corner Grounded Delta Solidly (effectively) grounded (LRG) Solidly (or effectively) grounded systems connect (bond) the system neutral directly to earth ground. Occasionally you may have an application that is a delta voltage source with a grounded “B” phase, also known as corner grounded. If that isn't possible, then the drive should be labeled as unsuitable for the floating delta and/or corner grounded delta. It is used to reduce wiring expenses by utilizing a service cable that has only two insulated conductors instead of the three insulated conductors typically. Per NEC, not for use with ungrounded systems, impedance grounded systems or corner grounded systems (com-monly known as Three Phase Three Wire Delta, Three Phase High Leg Delta and Three Phase Corner Grounded Delta systems). See Figure 4. NEC expert Mike Holt explains how to properly ground a corner grounded delta system and the special characteristics of these rare systems. Der PE-Schutzleiter (GND) darf keinen Strom tragen! Der Neutralleiter N (Grounded Conductor) ist dabei als getrennter Leiter anzulegen und erst innerhalb der Verbraucherablage abzugreifen. This normally would not be to big of an issue however the Haas machine VFDs and servo amplifiers probably require the 277 for surge overload and if a storm hits or we get a fault. Subsection 250. The generator cannot be configured to the 480 delta per manufacturer. Image used courtesy of Lorenzo Mari . Because of the disadvantages of not grounding systems, electrical designers had to integrate a ground reference to existing configurations. 24(D)(4) This section covers impedance grounded services. In most cases a corner grounded delta is a very poor choice of supply as it has a. 240V. A high-leg system is a hybrid between a standard 3-wire single phase and a 3-phase system. g. My proposed fix is: 1). 480V. 120V. Technologic & IPC Set Parameter 14. 14. True False. As the project is presently designed, we are stepping this down to 208/120Y and serving all of the building's loads via the 208/120V distribution system. Most utilities would require for you to request a variance to get ungrounded Delta now, so if you don't ask for it, you get corner grounded. It is very uncommon to have 3 phase in residential in the US but other parts of the world it is. If it is a corner grounded delta, the grounded phase must be* grounded AT the transformer terminal, meaning you will be able to SEE the ground. . This demonstration video shares the wiring, voltage and history of a corner grounded delta bank. MRG, Article 200. Introduction Corner-grounded delta systems are not re commended for new installations. e. However this grounded leg will be 480 volts phase to phase but no voltage to ground at the service and the inverter. 3 (f) This is applicable, only if it is a center tapped delta, 240/120 3P 4W. B-Grd: 0V (assuming B ph is the grounded phase) C-Grd: 240V. If you don't have VFDs or servos to contend with, then the NEC requires that you have EITHER a continuous ground fault monitoring system on an ungrounded Delta service, or you must use a "corner grounded" Delta system, wherein you tie one leg of your 480V transformer output directly to ground. The grounded phase has no voltage to ground (at the service) and 240 or 480 volts to the other two phases. 4. Schneider Electric has tested equipment for use on corner-grounded delta systems to provide Underwriters Laboratories Inc. False. Three-phase — 4-wire 120/240 volt delta connected system (high-leg). A circuit breaker with a slash rating, such as 120/240V or 480Y/277, shall be permitted to be applied in a solidly grounded circuit where the nominal voltage of any conductor to ground does not exceed theThe system is “corner grounded”, one leg of three phase delta is tied to ground. Claim this business (250) 884-1942. It consists of a maximum current and the voltage at which the device is rated to interrupt the circuit. #1. 242. LHL361005861). Neutral Conductor. Frame size EMC filter (+E200) screw Ground-to-phase varistor screw R10, R11 EMC AC VAR Drive. 5 . #1. Alehman. Now, there are exceptions. Normally the grounded conductor is A or B phase- but you never. 20(B)(1) and avoid an NEC violation. domnic Senior Member. You have a different problem. Re: Ground Fault Protection in Corner Grounded Delta System. My question is on the secondary side I need to take a bonding conductor from any of the three phase to ground to created a corner grounded delta, I know I've done a set up like this in the past but grounding a phase always makes me. Corner-Grounded Delta System. Although delta windings are often operated ungrounded, a leg of the delta can be center tapped and grounded, or a corner of the delta can be grounded. Although delta. Schneider Electric has tested equipment for use on corner-grounded delta systems to provide Underwriters Laboratories Inc. The purpose of bonding c. Question, when connecting a Wye generator to the Corner Grounded Delta, will. A diagram of such a system is shown at __ in figure 304. Corner grounded Delta transformer systems are known to confuse people. 2, the transformation ratio is 4160 divided by 120, or 34. Start shipping your package by locating a Purolator drop box, Purolator Shipping Centre, or Purolator Authorized Shipping Agent near you. Corner grounded delta is cheap. You still must run a separate grounding conductor to bond non current carrying components - so you are running 4 wire circuits either way you do it. 9. See Figure 11. The system has accidentally become a corner-grounded delta system with little, if any, current flow. The inverters may not like the elevated voltages to ground. B phase is bonded to ground at the transformer lugs, not in the switchgear. Two of the most significant tests performed on a TVSS are the measured limiting voltage test and a series of abnormal overvoltage. High-leg Delta "HLD" B/HL A N C G High-leg Delta This supply system configuration is not used in Europe. And, without proper identification of the. Schneider Electric has tested equipment for use on corner-grounded delta systems to provide Underwriters Laboratories Inc. Read also : what is an operational amplifier. Corner Grounded Delta You don't see this on new services much these days, but it is very common on older industrial buildings. 73=796. Refer to the Digest, CAD drawings, or device wiring diagram(s. A phase 490-ground B phase 490-ground C phase 0. Grounded Systems Ltd Company Profile | Victoria, BC, Canada | Competitors, Financials & Contacts - Dun & BradstreetHotel Pulitzer, Amsterdam; L’Hermitage Vancouver, BC; Four Season Nevis, BVI; Rosewood Miramar Montecito, CA; Residences at Little Nell Aspen, CO; St Regis Bal. not smaller than the size of the grounding electrode. iceworm Curmudgeon still using printed IEEE Color Books. About us. This is a system where one of the phase conductors of the 3-phase delta bank is intentionally grounded. The service company sent us a Magnum Power Genset (by Generac). Pretty curious though. “A circuit breaker with a slash rating, such as 120/240V or 480Y/277V, shall be permitted to be applied in a solidly grounded circuit where the nominal voltage of any. Not sure if that's the technical name or not. Corner grounded delta. 26. Grounded B-Phase Systems (Corner-Grounded Delta) PowerPacT B Electrical Accessory Wiring Diagrams. For example, a 480 V, 3-phase, corner-grounded, delta-connected system cannot use a 480Y/277 V circuit breaker because the voltage of two phases to the ground exceeds 277 V. Can’t do line to neutral loads but phase to phase single or three phase loads are fine. In a corner grounded delta system, one of the three phase legs is intentionally grounded. A grounded wye system has each phase at line voltage divided by the square root of three above ground. . Grounding center of one side (high leg 240/480 delta) might still be too high a voltage. When connected to the no. Corner Grounded Delta. The corner grounded delta (CGD) is one of the earliest forms of grounded systems in electrical installations. Measuring current of the grounded conductor at load side of the meter socket gave. A second fault, on a different phase, however, presents a problem. 5. I am in north Texas, where usually when I see a corner-grounded delta, it is really a pretty old ungrounded delta that has a ground fault or multiple faults on the same leg. They are available. 120V. teal854t Discussion starter · Oct 13, 2010. The minimum size of the grounded conductor for a 3-phase, 3-wire, corner-grounded, delta connected service is a. They could have a neighboring property causing that or could be monitoring lamp or relay seeking a fault. 6. Power company recently replaced transformers and now that businesses are opening back up. Per the NEC, you need either GROUND FAULT MONITORING, OR you need to use a Corner Grounded Delta system. #1 · Feb 28, 2020. On the primary side, what is the voltage to ground on each phase? If one is zero and the other two are 480 or 525 then yes it is a corner grounded system. Aprenda cómo usar la pantalla y el teclado integrados, así como las opciones de comunicación y control. A 480 Δ — 240-volt 3-wire Δ transformer is delivering power to a 3Ø load and has 75 amps of coil current flowing through each winding. Systems from Intermittent Ground Faults Introduction Many papers and standards [1][2][3][4][5][6] have discussed grounding of an electrical distribution system. Never ran into that before. 3-phase corner-grounded delta or single-phase circuits (NEC 240. I wasn't sure what issues it might cause having one of the phases to ground be 0 volts. It is the best way to connect two transformers with different voltage ratings when a 4-wire or a wye connection is not viable or practical. Unless its to. Corner-grounded delta: One line conductor is grounded directly. What about a corner grounded delta? This is still a grounded system but does not have a "neutral" per say. 120 V, 3-phase, corner-grounded delta. D1-D4 lumen packages only. A two-pole circuit breaker shall not be used for protecting a 3-phase, corner-grounded delta circuit unless the circuit breaker is marked 1φ–3φ to indicate such suitability. 240 V, 3-phase, 3 W, ungrounded or corner grounded delta V. In another thread about imbalanced voltages and currents the POCO decided to change a corner grounded delta well service to a delta with high leg. Delta with Wild Leg. 3. A two-pole circuit breaker applied on a 3-phase, corner-grounded delta system must be marked 1Φ-3Φ. It is found that, although this type of service is less expensive than solidly grounded wye service, 480 V corner-grounded delta service may not provide a safe working environment if used for oil-field service. Business, Economics, and Finance. 73) - Upon ground fault, the faulted phase L-G reading is zero and the other two. 220. I think it also allows you to use single phase panel boards also. You need transformers with a wye secondary and ground the center of the wye. Solidly (effectively) grounded (LRG) Solidly (or effectively) grounded systems connect (bond) the system neutral directly to earth ground. I've been given two different answers for the same set-up. 480 3ø, 3W corner grounded delta (ground jumper goes from one of the phases to ground. The NEC® addresses slash voltage ratings for circuit breakers in 240. Good points. For example, a corner-grounded delta system has a grounded phase conductor and no grounded neutral conductor present. There are circuits where grounding is prohibited. 1. If the phase line was solidly grounded you would be reading 0 volts. A corner grounded delta service can be designed for any desired voltage, but 240 is most common. The primary can be grounded wye, ungrounded wye or delta while the secondary can be anyone one of those not having to match. I know you cannot get any 120v loads but what about single phase 240v loads. Corner Grounded Delta Solidly (effectively) grounded (LRG) Solidly (or effectively) grounded systems connect (bond) the system neutral directly to earth ground. Lexington KY. It could also prohibit a corner grounded 240V delta since using a grounding transformer a 240V system could be grounded with a L-G voltage of only 139V. Per NEC, not for use with ungrounded systems, impedance grounded systems or corner grounded systems (commonly known as Three Phase Three Wire Delta, Three Phase High Leg Delta and Three Phase Corner Grounded Delta systems). Taipower, our elecricity service provider, mostly provides an 11. 120 V, 3-phase, corner-grounded delta. We have a project where we are changing the service from 480/277V, 3-phase, 4-wire wye to 480V, 3-phase, 3-wire, corner grounded delta. & below. If you had a corner grounded delta, B phase grounded and A phase shorts assuming you protected everything per the NEC you would have a ground fault and the fuses would blow or the CB open. You only need two current transformers to monitor the power in a 3 phase, 3 wire system. To visualize this, imagine the voltage triangle with all three sides = 480V and the phase connections at the three corners. Location Michigan Occupation Electrician Feb 24, 2023 #4 This is a 4 wire 3 phase delta high leg system. The derived neutral connot operate at 0 volts as this would mean there is a short circuit to ground. looking for advice on working on a 3 ph, 3 wire 480 delta that i believe fits the definition of a corner grounded delta. . If a solidly grounded neutral conductor is also being brought to the MCC, the power system is a 4-wire. The line is also safe to touch even when it is not properly bonded only when the load is shut off. It's 830 wye. 85). Scanning through 250. The purposes are to: limit overvoltages due to lightning, line surges, or accidental contacts with higher-voltage. 85 permits one pole of a motor controller to be placed in a permanently grounded conductor provided the controller is designed for all conductors. Corner-Grounded Delta (Grounded B Phase) Systems 2700DB0202R2/09 Data Bulletin 02/2009. This freaks people out, but it is totally legit. Grouch1980 said: Actually I didn't specify it. #4 · Oct 2, 2020. 3–Phase Corner-Grounded Delta System using 2-Pole Circuit Breakers. See Figure 11. The purpose of a corner ground is equipment and personnel protection. Just be aware: There is a very distant possibility that this electrical service is a corner-grounded delta, which has a grounded phase that cannot be fused by code. ppsh41pro • 10 mo. 277V. On the secondary the voltage would be, if. On 600 V, 200 A switches, 100,000 A max. For a fault current of 5A, primary current will be 5 divided by 3, or 1. Figure 4 – Fault to Ground on a Corner-Grounded Delta System A disadvantage of Corner-Grounded Delta systems is the inability to readily supply voltage levels for fluorescent or HID lighting (277V). 8kv/480V Y transformer. IN reference to. The other two phased are at the line voltage above ground. b. The other two phased are at the line voltage above ground. Its hard to visualize attaching 1 of 3 energized lines to ground. This would be a service like an ungrounded delta or a corner-grounded delta. ” Following areYou are correct in that a corner grounded delta would have 240V L-L x3, the corner would have 0V to ground. 10656 posts · Joined 2007. I have a job where they want to install a Dan Foss FC202 on a pump. Figure 4 – Fault to Ground on a Corner-Grounded Delta System A disadvantage of Corner-Grounded Delta systems is the inability to readily supply voltage levels for fluorescent or HID lighting (277V). 3–Phase Corner-Grounded Delta System using 2-Pole Circuit Breakers. Leave EM1 connected. test Learn with flashcards, games, and more — for free. Class R fuses are rated for 100 kA, however without the rejection fuse clips - system is limited to 10 kA since Class H or K fused could be installed in the future. Corner grounded delta (CGD) As the disadvantages of ungrounded systems became better known, simple, low-cost method of establishing a ground reference on an. Delta grounded 240vSchematic diagram of (a) grounded and (b) ungrounded pv systems Grounded b phase wiring diagramPhase wire delta single grounded 480v transformer corner 480 ground system volt three 208 volts leg efficent than service open. You can run a typical two-wire line-to-line load off just a single pole breaker because on this. might occur when Phase A goes to ground on a 480V, B-phase, corner grounded delta system. . B would be 180 (ish) to ground. MRG, Article 200. I have seen corner grounded deltas for 3 phase motors, but my situation is a bit different. The equipment itself may generate an undesirable amount of capacitive current to the shell of the bed if it is powered by either. Also don't forget that NEC doesn't apply on the utility side of the interconnection point. Aug 14, 2018. It is a Delta and Split-phase hybrid. Until the service is restored we need to get power to the facility. In the setup the OP describes, the maximum voltage to ground would be 240, so he must use a straight 240 V breaker. And Delta ground monitor. At the transformer, the grounding electrode conductor, grounded phase, and equipment grounding conductor all tie together. 8]. One phase center tapped to derive a different voltage. 86 restricting their use to solidly grounded systems where the line to ground voltage does not exceed the lower of the two values and the line voltage does not exceed the higher value. The CB panel fed by the transformer secondary (240/120V) has a grounding electrode where the secondary center tap (neutral) is connected but as stated the corner grounded delta supply is not connected to it. The center of the Y, which is usually grounded, must not be connected to anything. Do not install them on corner-grounded, resistance-grounded, or ungrounded systems. ) 480 3ø, 3W Wye connected Impedance grounded system. So instead of 480VAC 3 phase being 277V to ground, it was also 480V to ground thus being a bigger risk if accidentally grounded during troubleshooting. We have a 480 only corner grounded delta service. 480 V, 3-phase, 3 W, ungrounded or high resistance grounded VII. So all of the breakers you. 3, July 2022 -Corner-grounded delta grids not supported at voltages of 400V / 480V Version 1. Corner Grounded Delta Transformer Bank. I asked them to take voltage readings between phase-phase and phase-ground just to make sure it is an un-grounded delta secondary. If an electrical system is grounded as a requirement or by choice, all the rules related to grounded systems must be applied. Question, when connecting a Wye generator to the Corner Grounded Delta, will it work without any abnormalities. Basic cheap plug-in breakers are “slash” rated, meaning 240/120V; they are rated 240V phase to phase, but 120V phase to ground. This question references Article 240. The grounded conductor of a corner grounded delta system is covered by the rules in Article 200, just like any other grounded conductor. See 250. UL Listed for use on 240 V Corner-grounded Delta Systems (Grounded B Phase). I've seen corner-grounded systems where one phase is tied to earth. That is a corner-grounded delta system. Image used courtesy of Lorenzo Mari . "C" phase is solidly bonded to ground. 90 posts · Joined 2007. b. Only for use with 480V Wye systems. It requires connecting the impedance grounding conductor. In most cases, the delta is "buried" with no leads. We use our trainer model made by Three Phase Innovations to. a Split Phase circuit with 120V from each respective leg to Neutral (residential power tap - grin). This is a system where one of the phase conductors of the 3-phase delta. Corner ground is exactly what the name says - one corner of the delta is grounded, the other two corners will be 480 volts to ground on such system. Yes, that is my understanding too. Open delta 480 volt service. I would call the 4rth wire a ground wire unless it was used for load unbalance. , Premises wiring systems generally are required to be supplied by a system that is ? and includes a grounded conductor. The other solution would have been to corner ground the 480 Delta, but I've posted before why I don't like that setup. Louis. (d) Separately Derived Systems. 20, Informational Note. A. However, some utilities still provide this system, and many old installations still exist. If you have a 3-phase motor on a center-tap system, the grounded conductor does not come into the picture at all. 102(C)(1) for sizing the grounded conductor. For starters the xformer 480 side, if grounded, all the load side gear and equipment must be approved for corner grounding-not likely. He said that it's about 240 volts so 128 volts to ground isn't that far off for a corner grounded Delta. In this case, the breaker manufacturer must be consulted to verify interrupting ratings and proper application. This video covers voltage relationship for a Delta source or load. No magic and no mysteries. Running the 480 as ungrounded presents a whole other set of issues. This wire must be white or grey, because it is a grounded conductor, even though it isn’t a neutral. 2 requires a grounded conductor in all premises wiring. ” Following are sketches of what the voltage source looks like with a breaker applied. PowerPacT B-Frame Let-Through Energy Curve. Schneider Electric has tested equipment for use on corner-grounded delta systems to provide Underwriters Laboratories Inc. Ungrounded Delta: - No phase is intentioally grounded. 2) Adding a grounding autotransformer. Also be aware that your gear will have to be listed for use with corner grounded delta and some loads are not acceptable for use on a corner grounded supply. For use on. Nema motor voltages so 460*1. Informational Note: An example of a system permitted to be grounded is a corner-grounded delta transformer connection. The conductor connected to the neutral point of a system that is intended to carry current under normal. What is the minimum size required for a copper grounded conductor of three phase, three wire, corner grounding delta system if the ungrounded. 'power' panels (e. But how is the corner grounded of a Δ. I believe that you are not supposed to connect any single phase loads between the high leg and the neutral. What we have is 4160V feeding 4 step down transformers that step it down to 230V Grounded B. Ungrounded Delta: - No phase is intentioally grounded. The system is a 240v 3phase corner grounded delta system with "B" phase intensionally grounded. CMP said: Sounds like you have an ungrounded delta system, and your getting a capacitive voltage reading to your ghost ground. D. a delta winding, with the corner ground not causing any difference to actual operation unless the higher voltage from tap to ground is a specification issue, or. They do make a reference to issues with control circuit isolation on corner grounded 400-500VAC systems, but no issue mentioned on a 240V delta. A to Earth = 524. This system has multiple transformers that go from 480-208 delta-delta and also 480v delta-208/120v wye. - All Line to ground voltages read (L-L/1. Corner-grounded Delta One line conductor is grounded directly. Look for 2 xformer cans on the power pole! Open Delta. 26(4) and 250. 7 taps I am getting 439 volts, but If I need higher voltage the connection can be. Remember, voltage is a difference in potential. Almost as if the utility decided to run an EGC for giggles. This includes the rules in 230. No, it is not showing the high side delta winding is corner grounded. Such faults are typically high impedance and at unspecified locations. As such it allows the OCPD to trip and clear the fault. 430. This is a delta - delta transformer. Perhaps it should be extended to cover the grounded conductor of a corner grounded delta with a 170% factor. Occupation. Apparently, code requires this conductor to be phased white or gray but many People outside of code apply alternate color tape to the conductor because this is also a. The correct solution is to use a 208 Delta X 480Y xformer. Then any corner of the delta arrangement is grounded (the B-corner-ground is customary) to create a neutral in the winding (labeled and colored usually gray and white as a neutral). This question references Article 240. It is both, ground and hot. Safety Switches Table 4 lists two-pole safety switches that are UL Listed for use on 240 and 480 Vac grounded B phase systems. One certainly would not corner ground a primary delta. If you built the system using say a corner grounded delta (say B phase grounded) then you would see high current from A to B and from C to B but I suspect. GameStop Moderna Pfizer Johnson & Johnson AstraZeneca Walgreens Best Buy Novavax SpaceX Tesla. B phase to ground you have 0V. Snap. I came across a code a while back about NEC not allowing circuits to. Same with "wild leg" center grounded delta, which is also becoming obsolete. If he has corner grounded delta then I could see misunderstanding ~500 volts to ground as a stinger leg - but there should be two legs that are ~500 volts to ground.