Wiring Investigation, for Stray Voltage MPSC U17897 Szymanski Farm 1375 Argyle Rd. Snover, MI

Transcription

1 Wiring Investigation, for Stray Voltage MPSC U17897 Szymanski Farm 1375 Argyle Rd. Snover, MI Prepared by Brian Prokuda, P.E.* Hartland, MI December 3, 2015 *Registered Engineer in Michigan and Ohio

2 Table of Contents Executive Summary... 3 Opinions Site Investigation Utility Service Main Service Shop Service Barn Service Table of Figures Figure 1.1 Site Plan of Szymanski Farm... 7 Figure 1.2 Three Line Diagram of entire Electrical System (at time of Measurement)... 8 Figure Utility Service Three Line Diagram... 9 Figure Utility Service Picture Figure Main Service Three Line Diagram Figure Main Service Panel Board Picture Figure Shop Service Three Line Diagram Figure Shop Service Panel Board Picture Figure Shop Service Triplex Drop Picture Figure Barn Service Figure Barn Service Panel Board Picture Figure Barn Service Riser Picture Figure Barn Service Grounding Electrode Picture Figure Barn Stanchion Ground Picture Figure Barn Service Sub-Panel Board Picture Figure Barn Service Milk Machine Electrical Picture Figure Barn Service Milk Machine Starter Picture Figure Barn Service General Parlor Wiring Picture Figure Barn Service Water Heater Picture Figure Barn J-Box without Cover Picture December 3, 2015 Page 2 of 21

3 Executive Summary The scope of this report was to evaluate the state of the electrical wiring system of the Szymanski Farm at 1375 Argyle Rd., Snover, MI. This property is a dairy farm located in a rural agricultural area in Michigan s thumb area. This work is being done per the Michigan Public Service Commission Director, Brian Ballinger s, letter dated September 23 rd, 2015 in pursuant to Case U A site visit was made on November 4 th, 2015 to evaluate the wiring system. There are four main areas to the electrical system described in this report as the Utility Service, Main Service, Shop Service and Barn Service. There have been many changes made to the Szymanski Farm electrical service, and this evaluation is based on the state of the system at the aforementioned date. The Utility Service is a 37.5kVA single phase transformer fed from Thumb Electrics single phase (line to neutral) primary feeder. The secondary of the transformer is 120/240V split single phase. The primary and secondary neutrals are bonded via a Ronk Blocker. The secondary feeder is 85FT triplex cable to the Main Service. From the utility meter can to the triplex cable at the top of the pole is three wire #4/0AWG AL service entrance cable. The meter can neutral is bonded to the case. Three #4/0 AL conductors then go from the meter to the Main Service panel. This is all done correctly and is in excellent condition. The Main Service looks to be recently upgraded. The panel is 200A with a main breaker. There is a grounding electrode conductor from the neutral bar to the first grounding electrode, 8FT away, continuing to the second grounding electrode 6FT away then continuing back to the neutral bar. The grounding electrode conductor should not make a loop, it should be a single continuous conductor from the panel to both grounding electrodes, ending at the last electrode. When a loop is formed, the opportunity exist for small circulating currents to be on the conductor. This currents can be created by several mechanisms. The Shop Service is fed via a 100A two pole breaker and the Barn Service is fed directly from the main panel bus, protected by the 200A main breaker. The Shop Service has four wire #2 AL service entrance cable going to the top of the pole and the Barn Service has four wire #4/0AL service entrance cable going to the top of the pole. Other than the looping grounding electrode conductor, this service is installed correctly and is in excellent shape. The Shop Service is fed from a triplex feeder from the Main Service Pole to the Shop. The neutral and ground conductors of the #2AWG service entrance cable at the Main service is connected to the bare messenger of the triplex cable, the bare conductor of the #2AWG service entrance cable is not connected at the top of the Main Service pole. This type of feeder is not allowed to remote buildings per the current electrical code, but there is an exception for buildings that were wired under earlier code revisions. There is a splice in the triplex feeding the shop. The splice in the bare messenger was done with a mechanical split bolt. This is of concern, because that connection could loosen resulting in the entire cable coming down or at minimum for the shop to lose its neutral and ground path for fault current to the Main Service. It is preferable that the bare messenger cable be continuous, or at least use a compression crimp splice designed for that purpose. While the Shop Service is acceptable, it is recommended that the service drop be replaced by a new continuous quadraplex, providing a separate neutral and ground conductor. When this is done it will be necessary to add a grounding bar in the panel, move the ground wires to that bar and remove the neutral to ground bonding screw. A new four conductor service entrance cable from the panel to the quadraplex will be required. December 3, 2015 Page 3 of 21

4 The Barn Service is fed from a quadraplex cable from the Main Service pole to the barn pole, then to the barn riser. The quadraplex anchor has broken free at the barn, leaving the weight of the quadraplex from the barn pole to the riser on the electrical cable connections. The grounding electrode conductor for the Barn Service is tied to the neutral bar in the panel. The stanchion equipment ground is then tied to the grounding electrode conductor. In addition the feeder grounds are comingled with the feeder neutrals. This creates a condition that allows neutral current to flow to the main service through earth as well as the stanchion potential to rise above earth potential when line to neutral connected loads are turned on. A good example of this is the voltage measured at the Cow Contact location, described in Mark Cook s report, when a coffee pot was turned on. To resolve a dangerous situation, the Barn Service must be rewired. There is a conduit riser existing, so it is recommended that individual insulated conductors be used from the panel to the quadraplex, so it is a very short distance of wire to be replaced. Ground bars must be installed and the feeder ground conductors moved from the neutral bars to the new ground bars. The grounding electrode shall be removed from the neutral bar and reconnected to the new ground bar. In addition to the above main panel, there is a sub-panel fed from the Barn Service panel. This sub-panel has the neutral to ground bonded together again. This is both a code violation and another possible source for neutral current to end up on the grounding system. In addition the sub-panel is fed with #6AWG but is connected via a HOM-A terminal point making it protected by the Barn Service 200A main. These conductors are only rated for 115A. the HOM-A terminal point should be replaced with a 100A breaker, the sub-panel should be refed with a four wire feeder, a ground bar should be added, the neutral should not be bonded to ground and the feeder neutrals and grounds should be separated. Being there are only three circuits in this subpanel, it may be more economical to just use the sub-panel as a junction box and bring three circuits from the main panel to feed these loads. Also considered critical is the breaker protecting the wash controller. The breaker is rated at, but the controller is fed with #12AWG, rated for. There are many problems in the barn wiring that should be addressed, but those mentioned above are the critical ones that are likely creating Cow Contact Voltage. The majority of the barn wiring is in the parlor room, a small space, and would be relatively inexpensive to wire correctly. It is recommended that a new Barn Service main panel and riser be installed using conduits to feed the equipment in the parlor area. A single point bonding point should be added to the grounding electrode conductor for equipment grounds. A conduit can be added from the new main panel to the existing main panel. The existing panel can be stripped so that it can be used as a junction box for the circuits feeding the barn outside of the parlor room. December 3, 2015 Page 4 of 21

5 Opinions 1. The Thumb Electric service to the property is well installed and appropriate 2. The Main Service is in excellent condition and installed properly, with the exception of the grounding electrode conductor. 3. The Main Service grounding electrode conductor should not be in a loop, it should simply go from the Main Service Panel Board to each grounding electrodes in one continuous path. 4. The Shop Service is in acceptable condition. It is fed with a three wire feeder using the neutral conductor for both neutral and ground. This is no longer permitted, but there is an exception for buildings wired under earlier code revisions where this was permitted. 5. The Shop Service has a splice in the triplex feeding this. There are compression splices designed for this purpose, but in this case a mechanical split bolt was used. 6. While the Shop Service is acceptable, it is recommended that the service drop be replaced by a new continuous quadraplex, providing a separate neutral and ground conductor. When this is done it will be necessary to add a grounding bar in the panel, move the ground wires to that bar and remove the neutral to ground bonding screw. 7. The Barn Service is unacceptable and much of the barn wiring is in poor condition. 8. The grounding electrode conductor for the Barn Service is tied to the neutral bar in the panel. The stanchion equipment ground is then tied to the grounding electrode conductor. In addition the feeder grounds are comingled with the feeder neutrals. This creates a condition that allows neutral current to flow to the main service through earth as well as the stanchion potential to rise above earth potential when line to neutral connected loads are turned on. A good example of this is the voltage measured at the Cow Contact location, described in Mark Cook s report, when a coffee pot was turned on. 9. To resolve a dangerous situation, the Barn Service must be rewired. There is a conduit riser existing, so it is recommended that individual insulated conductors be used. Quadraplex exists from the main service to the barn service riser, so this is a very short distance of wire to be replaced. Ground bars must be installed and the feeder ground conductors moved from the neutral bars to the new ground bars. The grounding electrode shall be removed from the neutral bar and reconnected to the new ground bar. 10. In addition to Opinion 9, there is a sub-panel fed from the Barn Service panel. This subpanel has the neutral to ground bonded together again. This is both a code violation and another possible source for neutral current to end up on the grounding system. In addition the sub-panel is fed with #6AWG but is connected via a HOM-A terminal point making it protected by the Barn Service 200A main. These conductors are only rated for 115A. the HOM-A terminal point should be replaced with a 100A breaker, the sub-panel should be refed with a four wire feeder, a ground bar should be added, the neutral should not be bonded to ground and the feeder neutrals and grounds should be separated. Being there are only three circuits in this sub-panel, it may be more economical to just use the sub-panel as a junction box and bring three circuits from the main panel to feed these loads. 11. As described in Section 1.4 of this report, there are many problems in the barn wiring that should be addressed. Those mentioned above are the critical ones that are likely creating Cow Contact Voltage. The majority of the barn wiring is in the parlor room, a small space, and would be relatively inexpensive to wire correctly. 12. It is recommended that a new Barn Service main panel and riser be installed using conduits to feed the equipment in the parlor area. A single point bonding point should be added to the grounding electrode conductor for equipment grounds. A conduit can be added from the new main panel to the existing main panel. The existing panel can be stripped so that it can be used as a junction box for the circuits feeding the barn outside of the parlor room. December 3, 2015 Page 5 of 21

6 1.0 Site Investigation This section shows detailed diagrams and pictures of the Szymanski Farm wiring. Figure 1.1 is a plan view of the farm showing the four electrical areas described in the report. There are also pictures to further identify these areas. Figure 1.2 shows a three line diagram of the electrical system. The four key areas are also identified on this diagram and are shown in more detail in other sections of this report. December 3, 2015 Page 6 of 21

7 Utility Service Figure Main Service Figure Shop Service Figure Barn Service Figure Barn Pole Figure 1.1 Site Plan of Szymanski Farm December 3, 2015 Page 7 of 21

8 Utility Service Figure OVERHEAD LINES FUSE LA Main Service Figure THUMB ELECTRIC 37.5kVA TRANSFORMER RONK BLOCKER GROUND RODS ARE 6FT APART PER NEC GROUND CURRENT IS FLOWING IN CONDUCTOR DUE TO GROUND LOOP. AT BASE OF POLE 20FT FROM BASE OF POLE THERE SHOULD BE A SINGLE GROUNDING CONDUCTOR FROM THE #4 BARE COPPER PANEL TO THE GROUND RODS. METER Shop Service Figure N BOND SCREW N B R W BARE 200A MAIN W 1 SHOP B R 2/0 SE AL XHHW-2 SHOP E AWG SE AL B R W BARE N BOND SCREW 4/0 SE AL XHHW-2 1 MAIN WELDER QUAD RECPT NEXT TO PNL LIGHTS RECPT ON BENCH 15A 15A 30A AIR COMP DUE TO IMPROPER WIRING, NEUTRAL CURRENT CAN FLOW THROUGH THE GROUND CREATING A GROUND POTENTIAL. 4/0 AL? APPROX. B R BARE USE-2 INSULATED Barn Service Figure #8 OR #6 SOLID 200A MLO TO GND ROD LOAD NEUTRALS AND GROUND N BOND TO BOX CONDUCTORS BONDING COMINGLED CONDUCTOR TO MILKING STANTON. BARN 200A MLO 30A SUB PANEL HOMA TERMINAL 30A MILK MACHINE SPARE WASH CNTL 15A SPARE 15A?A?A WATER HEATER Figure 1.2 Three Line Diagram of entire Electrical System (at time of Measurement). December 3, 2015 Page 8 of 21

9 1.1 Utility Service Figure shows the three line diagram of the utility pole connections. The connections are drawn as they are physically connected. The primary ground is continuous from the lightning arrester to the grounding electrode at the base of the pole. The primary ground has a loop to connect to the utility neutral and a pig tail from the Ronk Blocker is connected to the primary ground with a split bolt. There is a second grounding electrode conductor from the Ronk Blocker to a second ground rod 20 feet from the base of the pole. A pigtail from the transformer secondary to the secondary ground is made just below the Ronk Blocker. These connections can be seen in Figure OVERHEAD LINES FUSE LA THUMB ELECTRIC TRANSFORMER 37.5kVA RONK BLOCKER AT BASE OF POLE 20FT FROM BASE OF POLE Figure Utility Service Three Line Diagram December 3, 2015 Page 9 of 21

10 Figure Utility Service Picture December 3, 2015 Page 10 of 21

11 1.2 Main Service The three wire diagram for the Main Service is shown in Figure The red box points to the grounding electrode conductor that should be removed, as described above. Other than this, this service is excellent. Figure shows a picture of the inside of the panel. GROUND RODS ARE 6FT APART PER NEC #4 BARE COPPER GROUND CURRENT IS FLOWING IN CONDUCTOR DUE TO GROUND LOOP. THERE SHOULD BE A SINGLE GROUNDING CONDUCTOR FROM THE PANEL TO THE GROUND RODS. This conductor should be removed. METER B R BOND SCREW W N N BARE 200A MAIN W 1 SHOP B R 2AWG SE AL B R W BARE 4/0 SE AL XHHW-2 Figure Main Service Three Line Diagram December 3, 2015 Page 11 of 21

12 This conductor should be removed. Figure Main Service Panel Board Picture December 3, 2015 Page 12 of 21

13 1.3 Shop Service Figure shows a three line diagram of the shop service. The instructions in the red boxes show the changes that will be necessary if the service is refed with a four wire system, as recommended. Figure shows a picture of the inside of the shop panel and Figure shows the mechanical splice in the triplex feeding the shop. If refed with new quadraplex, relocate grounding electrode conductor from neutral to new ground bar. If refed with new quadraplex, add a new ground bar. Move feeder grounds from neutral and connect to ground bar. SHOP N BOND SCREW 1 MAIN 2/0 SE AL XHHW-2 E32071 New quadraplex and four wire service entrance cable. (Recommended) If refed with new quadraplex, remove screw. WELDER QUAD RECPT NEXT TO PNL 15A LIGHTS 15A 30A AIR COMP RECPT ON BENCH #8 OR #6 SOLID TO GND ROD Figure Shop Service Three Line Diagram December 3, 2015 Page 13 of 21

14 Figure Shop Service Panel Board Picture Figure Shop Service Triplex Drop Picture December 3, 2015 Page 14 of 21

15 1.4 Barn Service The three line diagram of the barn service is shown in Figure and the picture of the panel is shown in Figure The service riser, grounding electrode conductor and stanchion equipment grounding conductor are shown in Figures through DUE TO IMPROPER WIRING, NEUTRAL CURRENT CAN FLOW THROUGH THE GROUND CREATING A GROUND POTENTIAL. 4/0 AL? APPROX. B R BARE USE-2 INSULATED 200A MLO BONDING CONDUCTOR TO MILKING STANTON. BARN LOAD NEUTRALS AND GROUND CONDUCTORS COMINGLED N 200A MLO BOND TO BOX 30A SUB PANEL HOMA TERMINAL 30A MILK MACHINE SPARE WASH CNTL 15A SPARE 15A?A?A WATER HEATER Figure Barn Service December 3, 2015 Page 15 of 21

16 Figure Barn Service Panel Board Picture December 3, 2015 Page 16 of 21

17 Figure Barn Service Riser Picture December 3, 2015 Page 17 of 21

18 Figure Barn Service Grounding Electrode Picture Figure Barn Stanchion Ground Picture In Figure it can be seen that two wires are in the same whole of the pipe clamp. These connectors are typically only rated for a single wire. The equipment ground should either utilize a connector that allows for the wire to be continuous or a second clamp should be used to continue the equipment ground to the next equipment. Figure shows the sub panel fed from the Barn Service main panel. Figures and show the milk machine controller with unprotected wires draped along the wall. Figure shows more unprotected wiring in the parlor. Figure shows the water heater with unprotected from the ceiling to the termination box and Figure shows an electrical box December 3, 2015 Page 18 of 21

19 with no cover. These last two items are minor problems, but are provided to show the general state of the wiring in the barn. Figure Barn Service Sub-Panel Board Picture Figure Barn Service Milk Machine Electrical Picture December 3, 2015 Page 19 of 21

20 Figure Barn Service Milk Machine Starter Picture Figure Barn Service General Parlor Wiring Picture December 3, 2015 Page 20 of 21

21 Figure Barn Service Water Heater Picture Figure Barn J-Box without Cover Picture December 3, 2015 Page 21 of 21