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S&B 2011 Agricultural Buildings Electrical Q&A's 1. Should a diesel fuel pump be wired to meet the requirements in Art. 514.Answer - Yes. Art. 514 applies to all motor fuel dispensing per 514.1. Diesel fuel is not considered a flammable liquid and the area would be considered unclassified 514.3. A ny of the appropriate wiring methods of Chapter 3 could be used. However, all requirements of Art. 514 shall be followed such as disconnecting means, grounding and bonding. 2. Do I need to install in-use covers on all receptacles in the barn? Answer - Yes. NEC 406.8(B) requires all 15- and 20-ampere 125 and 250 volt receptacle receptacles located in a wet location to have covers that remain weather proof whether or not a plug is installed. A wet location is described as underground, vehicle washing areas, or areas exposed to the weather. Damp is described as protected from the weather and not subject to saturation and would require a cover approved for damp locations - a cover that protects the receptacle when the cover is closed, no plug installed. Some locations require wet location covers - milk parlor, or milk house. Some require damp, such as open-walled barns or areas protected from weather. Weather-resistant receptacles are required in wet and damp locations. 3. If I run a new 4-wire feeder to the house is there anything else I need to do in the house? Answer - Yes. If there is an electric range, electric clothes dryer, or feeder panelboards that have a 3-wire branch or feeder circuit supplying it will have to be changed to 4-wire circuit. The code has never permitted 3-wire feeders, although many were installed that way. Look for parallel grounding paths with other buildings (such as a shared LP gas tank or metallic water piping) and if present they must be properly isolated or the other building/s must be converted to 4-wire also. See NEC 250.32(B) Exception and 250.140. 4. The new free-stall barn we are wiring is supplied with a 277/480 volt system. We installed a 15 KVA 120/208 transformer at the opposite end of the barn and used the equipment grounding conductor run with the primary circuit for the grounding electrode conductor of the separately derived system. I don’t see a problem because it is connected to the same terminal bar in the service equipment as the grounding electrode. But a state inspectors is saying this is a violation. Answer - It is not code compliant. This has never been allowed and now the 2011 NEC 250.121 will make that clearer. They serve two different purposes. The equipment grounding conductor should only have current on it in the case of a ground fault. It’s not uncommon for the grounding electrode conductor to have a small amount of current flowing on it under normal conditions. 5. I installed a one HP and a 1½ HP motor on the same branch circuit. The branch circuit is 240-volt single phase and is protected by 20-ampere circuit breaker. My problem is at times when I try to start the second motor the circuit breaker trips. I would like to increase the circuit breaker to a 25-ampere breaker. The motors have thermal overload protection built into them, so I don’t think it will be a problem. Answer - It is not permitted by code. You are required to meet the requirements of NEC 430.53(B) for more then one motor on a branch circuit unless they are all one HP or less. This requires the smallest motor to be protected, not to exceed the requirements of 430.52. Table 430.248 indicates full load of one HP motor is 8 amperes. Table 430.52 allows 250 percent increase for inverse time circuit breaker. 8 X 2.5 = 20 amperes max. 6. Although I have never installed one, several of my customers do have isolation transformers installed. I am hearing now that they are not allowed per 2008 NEC. Is this correct? Answer - That is correct, per 2008 NEC 250.32(B). With the adoption of the 2008 NEC came a requirement to install an equipment grounding conductor with all new branch circuits or feeders supplying separate buildings or structures. There is only one exception to 250.32(B), which permits existing installations installed prior to the adoption of the 2008 NEC to remain with conditions. 7. We installed a new 200-ampere 120/240 volt circuit breaker panel on the outside of a manure equipment room. The motor controllers are located adjacent to the panel board. Are we required to install disconnects within-sight-from the motors located in the equipment room? Would I be allowed to install breaker locks instead? Answer - A disconnecting means is basically always required to be located within-sight-from a motor controller supplying a motor of 1/8 HP or greater per NEC 430.102(A). Per 430-102(B), a motor disconnect is required to be located within-sight-from any motor rated 1/8 HP or greater. Exception (a) to 430.102(B)(1) and (2) permits a motor controller disconnect which is capable of being locked in the open position to act as the required motor disconnect where the designer, installer, or authority-having-jurisdiction determines that it is impracticable or creates a greater hazard to install the disconnect within-sight-from the motor. 8. My customer wants me to install a receptacle in her free-stall barn for a tractor block heater. Past experience has me concerned with GFCI being subject to nuisance tripping. Would I be able to install a single receptacle and comply with the code? Answer - Yes, with conditions. A single receptacle is allowed for a dedicated load where a GFCI protected receptacle is installed within 3 feet of that single receptacle. The 2011 NEC 547.5(G) removes this provision and basically requires every 120V 15- or 20-ampere receptacle installed on a farm to be GFCI protected. The code panel’s reason for the change is from product listing requirements which does not allow product current leakage to exceed .75 MA (a GFCI trips between 4-6 MA leakage). 9. I installed a new 200-ampere 120/240 volt feeder to a new calf barn using four conductor 4/0 USE cable. The inspector said I cannot bring the USE cable into the building. Is he correct? Answer - Yes. USE cable cannot be used on the interior of a building per NEC 338.12(B)(1). Use a dual rated cable such as USE/RHW, which would allow you to bring it into the building or splice to an approved building conductor on the outside. Also, 547.5(F) requires equipment grounding conductors for ag buildings to be copper. If the conductors are installed underground they are required to be covered or insulated. 10. We are installing a new 800-ampere 277/480 volt 3 phase service for a new dairy. What size equipment bonding jumper is required to ground the CT enclosure? Answer - Size is based on the size of the service conductors. Service conductor enclosures such as metering equipment, raceways, wireways, etc. are required to be bonded by NEC 250.92(A). How to size them is found in 250.102(C). Supply -ide bonding jumpers are sized depending on the size of the service conductors using Table 250.66. Example; two paralleled 500 KCMIL copper cond. would require a minimum 2/0 copper bonding jumper. 11. We used PVC conduit to wire our lighting in a new free-stall barn. The inspector indicated we need to install expansion joints in the conduit runs between the boxes. I thought we only need expansion joints when installing PVC outside. Answer - They may be required inside or outside depending on temperature differential. NEC 352.44 indicates expansion joints are required where expansion more than .25 inch can occur. Table 352.44 gives expansion characteristics. Example; 50 degree change 2.03-inch/100-foot. 2.03/100 = .0203 per inch. 0.023X20 foot = 0.406 inch expansion. 12. Our customer does not want to install an equipotential plane in his new free-stall addition. Is there anything we have to watch for when installing the electrical system? Answer - Comply with 547.10(A) and (B). Equipotential planes are required in indoor confinement areas with concrete floors where metallic equipment is located that may become energized and is accessible to livestock. An equipotential plane is required in all livestock buildings required to be bonded per 250.104(C). Where the building is wood frame or partial wood frame with steel columns, there are alternative solutions such as creating an isolation from metal parts that could become energized that may come into contact with livestock. Equipment installed in outdoor livestock areas that may become energized are required to have an equipotential plane with gradient ramps installed. 13. We have a 400-ampere fusible service disconnect supplying a grade level Ronk transfer switch. The transfer switch then supplies two 200-ampere panelboards. The feeders to the panelboards are 3/0 copper with a #6 AWG copper equipment grounding conductor. Is the #6 equipment grounding conductor too small.? Answer - The equipment ground is required to be sized for the overcurrent device supplying the circuit 250.122. Table 250.122 indicates a minimum #3 AWG copper for a 400-ampere overcurrent device. 14. I don’t like to use PVC conduit on the outside of building to supply equipment, but I do because of cost. I install expansion joints where needed and support it at no more the 10-foot intervals. Over time it still starts looking like a snake. What else can I do? Answer - Ten-foot intervals of support apply only to metal conduit. PVC conduit is required to be supported at intervals indicated in Table 352.30. Example: .5-inch through one-inch, not more then 3 feet. 1.25-inch through 2-inch, maximum. 5 feet between supports and securely support the raceway within 3 feet of fittings. 15. On a project we just finished the plumber installed some yellow flexible gas piping to the water heater. Now the inspector wants us to install additional bonding to it. I think we already met our requirement by grounding the gas dryer. Answer - You are correct, though the additional bonding is needed. The piping you refer to is CSST. The manufacturer’s instructions require additional bonding in addition to what you have done. 250.104(B) requires bonding of other metal piping such as gas piping. It indicates the equipment grounding conductor for the circuit likely to energize the piping can serve as this bonding means. The installer of the CSST is responsible for installing it to manufacturer’s instructions. 16. A new facility we are wiring will have a 277/480 volt service and 120/208 system for the lighting and receptacles. Is there anything special we need to do to identify the two systems? Answer - Yes. Identification of conductors when you have multiple voltage systems in a building is required by NEC 210.5. It indicates the grounded conductors shall be identified by 200.6 which requires different identification of each systems grounded conductor if they share raceways, cables, or enclosures. 210.5(C) requires identification of ungrounded conductors. They shall be identified by phase and system, by color coding or other means at all terminations, and splice points. SPS 316.210(1) Note identifies traditional colors used for 277/480 brown, orange, yellow and 120/208 black, red, blue. The system identification is required to be posted at each panelboard. 17. Am I required to GFCI protect a cattle waterer? I am worried about them tripping allowing the waterer to freeze. Answer - Yes, where a 125 V, 15 or 20 A receptacle is installed to supply the equipment. GFCI protection is not required for cattle fountains that are direct wired or when supplied from a 240 V receptacle outlet. They could be supplied from a 125 V 15 or 20 A receptacle where a GFCI protected receptacle is installed within 3 feet per 547.5(G) (last paragraph). 18. I recently lost a project to another contractor to install a generator and automatic transfer switch on a veal farm. I later found out the other contractor sold the farmer a smaller system then I had bid. I did a load calculation that showed the farmer my generator was the minimum size needed, but he went with the other stating he would just turn off some of load if needed. Is this code compliant? Answer - No. That is an optional standby system and must meet the requirements of Art. 702. Where an ATS is installed NEC 702.4(B)(2)(a) indicates the source must be capable of supplying the full load transferred or (b) shall be provided with automatic load shedding. 702.4(B)(1) allows the use of a manual transfer switch being used with the owner deciding what he manually selects to supply. 19. I installed a new branch circuit and disconnect for the vacuum pump in the equipment room of a new parlor. I located it where the milk equipment people indicated and they installed the controller directly above the pump. I don’t think this is correct. Answer - You may be right. Equipment that may require servicing or maintenance while energized is required to comply with Table 110.26A)(1) for working space. 20. The plumber installed several water pipes above my panels in an equipment room. I told him they have to be moved or to install a drip pan below to protect my panels. Will this be OK? Answer - Maybe. The dedicated equipment space is described as the space equal to the width and depth of the equipment, extending from the floor to 6 feet above the equipment or the structural ceiling, whichever is lower. See NEC 110.26(E)(1). The drip protection is required to be located above the dedicated equipment space. 21. I ran direct-buried conductors out to the new calf shed. The conductors are fed out of an at-grade distribution panel. The conductors were aluminum with USE-2/XLPE insulation. Can I also use an aluminum equipment ground with the same insulation? Does the equipment–grounding conductor have to be “full sized”? Answer - No. Equipment grounding conductors installed below grade shall be insulated or covered copper where the circuit supplies areas falling under the scope of 547.1 (where livestock is present). Because the feeder is supplied from an overcurrent device rather than a site isolation device, 547.(B)(3)(1) does not apply. 338.12(B) Type USE conductors may only enter the building when additional conductor marking such as RHW or XHHW is present and where installed in raceway. 22. I’m bidding a free stall barn with 24 fans located throughout the barn. Can I use manual motor starters as the disconnect? The fans are turned on and off through a thermostatically controlled contactor. Answer - Yes. Comply with NEC 430.102(A), 430.102(B), and 430.109(A)(6). Definition of within-sight: See it from the controller or motor location and 50-feet max. 430.102(A): Must have a disconnecting means within sight of the motor controller. 430.102(B): Must have a disconnecting means within sight of each motor. 430.109(A)(6): Manual motor controllers only permitted as the required disconnect if marked “Suitable as a Motor Disconnect” and located downstream of the branch circuit protection or internally provides branch circuit protection per 430.52(C). 23. I’m running a new 200-amp four wire feeder to an existing barn. The phase and neutral conductors are 4/0 XHHW aluminum and I’m using a 6 AWG copper equipment grounding conductor. The water supply at the barn is plastic, but there still is metal piping in the milk house and barn. Can I just use a couple of rods to ground the feeder? Do I have to bond the water? Answer - Yes and Yes. All electrodes at the building served shall be bonded together and used as the electrode system. If there are no existing electrodes, installing two ground rods is OK. If the feeder supplied a new building, rebar in footing would have to be used as the electrode. If there is no rebar in footing, there is no requirement to add it. Two rods are then OK. NEC 250.104(A) requires “interior metal water piping systems” to be bonded. The bonding conductor is sized per 250.66. Bonding permitted to water line at any point. Use 10-feet of metal piping as minimum length required to bond. 24. We’re building a fan control panel with combination motor starters. Each starter has a “short-circuit protector,” a contactor, and an overload block. Each starter supplies only one motor. The sales engineer told me we don’t need a fuse block ahead of each starter if we order a “line side adaptor” with each one. Is this OK? Answer - There are several issues to examine. Consider Comm 16.012-(1) - Are the starters marked “CE,” or listed by UL, ETL or other NRTL. NEC 409.110 requires control panels be marked with information including the short-circuit-current rating. What is the short-circuit current? Are the products listed for that available short-circuit current without upstream current limiting fuses? 430.109(A)(5) - Is the product listed as a “self-protected combination controller” with the line side adaptor? 25. The farm has a diesel fuel tank. The pump sits on top and currently is wired with a orange extension cord. I know that’s not right, but do I need RMC, seal-offs, etc., just like a gas pump? Do I need a disconnect within sight? Answer - No and Yes. See NEC 430.102(A) and 514.11(B). 26. There is a room housing the manure pit at the end of the free stall barn. I can put the contactor for the pump outside. I know I need a disconnect within sight of the pump motor. Is a knife-switch in a 3R enclosure OK? Answer - No. NEC Table 110.20 permits a NEMA 4X or 6P enclosure in corrosive locations. NEC 430.102(A) requires a disconnecting means within sight of the controller. 430.102(B) requires a disconnecting means within sight of the motor. The exception does allow the controller disconnect to be used to meet this requirement if placing the disconnect near the motor creates an increased hazard. The controller disconnect must be capable of being locked-off if the Exception is used. Check with the inspector to ensure your interpretation of the exception is the same as theirs. Another alternative is a horsepower-rated cord and attachment plug assembly. This permits the motor to be easily disconnected when the pump is pulled for maintenance or repair. 27. I’m installing a new service and motor controller for a well pump. The pump is a quarter of the way into the field and close to the pivot point. Service is by the road. We are using a 200-amp fused switch as the service disconnect. My apprentice said I need to order “rejection clips.” Do I really need to use them? Answer - Yes. Service equipment is intended to operate under fault conditions. It must have the proper interrupting rating. The minimum available fault current for agricultural services is usually 22,000-amperes. Current-limiting-type fuses are required for this application. The rejection clips are an accessory kit for the fused switch. When installed, they physically block the insertion of non-current limiting fuses. The 2011 NEC will require that service equipment be field marked with available fault current values. 28. We need to get the barn “four-wired”. Can we use the existing drop and add a insulated conductor? Answer - That’s up to the authority-having-jurisdicition. There are factors to consider: 1.) Is the drop at the proper height -18 feet above any driveway or yard that machinery can access is the minimum? 2.) Is the messenger wire strong enough to carry the additional weight? You could compare the size of the messenger to the size required for a new four-wire drop over the same distance. 29. A barn is wired with a three-wire drop from a pole-top transfer switch. The project involves a new 4-wire drop and isolating the neutrals and equipment grounding conductors within the barn panel. A metal water pipe runs from the well to the barn and another metal pipe runs from the well to the house. Do we have to four-wire the house? Answer - Yes. NEC 250.32(B) Exception applies to existing buildings. It permits an existing bonded neutral to be used as the equipment grounding conductor with conditions. The second conditions applies to this situation. There can be no continuous metallic paths bonded to the grounding system in each building. Either the metallic water line must be isolated so that there is no continuous path between the buildings. Or the house must also be four-wired. 30. My customer has a pole-top disconnect that is failing. Can we replace the pole-top switch? Answer - Yes. This is a repair to an existing installation under NEC 547.9(A) and the prior SPS 316.42 Note. Beware of the required short-circuit rating of the new switch and the utility’s available short-circuit current. The rating of the site isolation device (pole top) must be rated equal or greater than the available short-circuit current. 31. I have 169 feet of NM cable left over from my silo-room project. Can I install NM-B cable in the hay mow since it is a dry location? Answer - No, it is not an accepted wiring method for agricultural use. See NEC 547.5(A). 32. I have a chicken plucking area that may be considered damp or wet location, we do hose it down when finishing up daily but, I would say it is not a corrosive environment like the inspector is calling it. Is she correct or just pulling my leg on another one of her trips? Answer - Yes, the inspector is correct, the devices must be suitable for that location and use, NEC547.1(B)(3) and 110.11 33. I have to run a new four wire 60-ampere single phase 120/240volt feeder over to a calf free stall barn area 300 feet away from the farm distribution point; which has the OCP at that location Due to voltage drop considerations, I increased the size of the phase conductors to # 1/0 aluminum USE-2. But I am not sure of the size I need for the equipment grounding conductor. I see per 250.122 (B) that I need to increase the equipment grounding conductor size as well. What does the term “sized proportionately” mean and how do I figure it? Per table 250-122, I only need a # 8 AWG, aluminum conductor. Answer - See NEC 250.122(B). You are wise to design for voltage drop. The Answer lies in the use of Chapter 9, Table 8, Conductor Properties and some calculations. Step # 1, calculate the size ratio of the new conductors proposed to be used (#1/0 AWG) to the conductors allowed to be used for the OCP, normally # 4 AWG. For the phase conductors and their respective circular mils area. Size Ratio= (# 1/0 AWG), @105,600 c-mil. Divided by (# 4 AWG) @ 41,740 c-mil; = 2.5 as a ratio. Now, take the allowed EGEC per 250-122 # 8 AWG aluminum @ 16,510 c-mil, times the ratio factor (2.5), which equals 41,275 c-mil and find the conductor that meets or exceeds that size. Per Table 8, a 4 AWG conductor is 41,740 c-mil and 4 AWG would be the correct minimum size. Thus it is proportional per the code requirement. 34. Per the requirements of NEC 547.9(E), identification is required when a building is supplied by more than one service that is 150 feet or greater apart and a permanent plaque or directory is required. What does it have to look like? Answer - Typically contractors use a foot print or site diagram of the building and identify where each of the services are located on the building. This diagram is required to be to be posted at both service locations. The same requirement applies to multiple site isolation devices or free standing services on a single agricultural property where located within 150 feet of each other to include identifying the buildings or structures served by each service. The 2011 NEC renumbers this section to 547.9(D) and deletes the minimum 150-foot separation requirement for required identification. 35. Why is it that slatted floors that are supported by the structure are not required to be bonded? I thought everything had to be bonded. Answer - Not slatted precast concrete floor planks See NEC 547.10(B). Because the precast concrete slatted flooring spans across a pit below there is a reduction in livestock contact to earth potential. The slats may be bonded to an equipotential plane if desired, but it is not required by code. 36. I know someone who believes that an on-site isolation transformer will cure all his farm’s poor wiring and equipment operating problems. He is on his third transformer and I think the electrician that installed it did not do a good job of system bonding. For one thing, a yard service pole has a guy wire coming within 3 feet of the transformer. The transformer is only up in the air 6 feet above grade. Answer - See NEC 250.110-(1). As you have indicated, it is not installed properly. No equipment grounding connection is required if the transformer is 8 feet vertically and 5 feet horizontally off of ground or away from other grounded metal objects and not subject to contact by persons. 37. Along my farm’s driveway I had a new grade level service 600 ampere single phase 120/240 volt service with a CT cabinet and a nonmetallic wireway going to three 200 -mpere panelboards. The inspector said I needed to have posts installed to protect the panels from damage from wagons or equipment going by. The old pole with the pole top disconnect was only hit three times over the 20 years it was there. Answer - It should not be getting run into. NEC 547.5(E), 110.27(B) says “All electrical wiring and equipment subject to physical damage shall be protected”, and “In locations where electric equipment is likely to be exposed to physical damage, enclosures or guards shall be so arranged and of such strength as to prevent such damage”. 38. I only have an existing three wire feeder going over to the machine shed and the power company is requiring that I four wire the existing panelboards as part of their funded program work. Can I plow in an equipment ground wire close to the old trench line and meet the requirement. Answer - No. See NEC 300.4(B). The requirement states all conductors of the same circuit and (where used) the grounded and equipment grounding conductor and bonding conductor shall be contained with in the same raceway, cable , cord or trench with the other conductors. Remember when you bring in the fourth wire you have to install a new buss for the equipment grounding circuit connection and isolate the grounded conductor (neutral) bus in the panel. 38. Who can do inspection work on farms? Answer - SPS 316.940 indicates that the person doing the inspection work shall be preformed by a certified inspector, a Commercial Electrical Inspector. However 316.920 Authority, states that the department is granted the authority and jurisdiction over the farm inspections. That Section (2) Municipal Authority does not mention farms or farming as a place where they can inspect. So the state inspectors as of now are the only folks authorized to perform those inspections and subsequent enforcement of code violations found. Changes may be coming down the trail with the latest proposed version of SPS 316, but are not in place now. 39. I am a man of many talents and besides farming, I install electrical wiring and plumbing on the side for family and friends and it all works properly. When Act 63 goes into effect on April 2, 2013 can I still do my own wiring on the farm and will it have to be inspected? Answer - No, you will not be permitted to install new wiring outside of your single family dwelling. Yes, inspections will be required. You are not permitted to install plumbing covered by the Wisconsin Uniform Plumbing Code. County Web sites || City/Town/Village Web sites || State Portal || Build Your Business The Department of Safety and Professional Services Safety and Buildings Division is an equal opportunity service provider and employer. If you need assistance to access services or need material in an alternate format, please contact us, 608-266-3151, TDD Relay dial 711 in Wisconsin or 800-947-3529. |