1. 240.87 Arc Energy Reduction.
Large electrical systems protected by circuit breakers with high trip settings have the potential for extreme arc fault events. Section 240.87 requires that these systems use some method that will limit these arcing fault levels.
Circuit breakers that have a continuous trip rating of 120 A or higher, and circuit breakers that are adjustable to have their continuous trip rating set to 1200 A or higher, must be provided with some type of Arc Energy Reduction. The 2017 NEC has expanded the choices for how this Arc Energy Reduction can be accomplished.
One new way to reduce the hazards of an arc flash is to provide an instantaneous trip setting that is less than the available arcing current. Another new way to limit arc faults is to provide an instantaneous override that is less than the available arcing current.
Under arc fault conditions, the longer the arc persists, the more dangerous it is to people and equipment. Reducing the amount of time that the faulted circuit is energized, will increase safety. Instantaneous trip settings for circuit breakers and instantaneous overrides that are set below the available arcing current are an effective way to reduce the arc energy because the circuit breaker will trip as soon as the instantaneous trip level is reached.
New Informational Note No. 3 explains how an instantaneous trip setting can reduce the clearing time of a circuit breaker: An instantaneous trip is a function that causes a circuit breaker to trip with no intentional delay when currents exceed the instantaneous trip setting or current level. If arcing currents are above the instantaneous trip level, the circuit breaker will trip in the minimum possible time.
This code change will provide a safer installation by including an instantaneous trip function as a way to reduce arc energy by reducing the amount of time the arc is allowed to continue.
QUESTION 1: Which of the following requires some form of Arc Energy Reduction?
A. 1000 A rated circuit breaker with continuous setting set to 1100 A.
B. 1000 A rated circuit breaker with adjustable instantaneous trip setting.
C. 1200 A rated circuit breaker with adjustable instantaneous trip setting.
D. Circuit breaker with maximum continuous current setting of 1100 A
2. 110.21(A)(2) Equipment Markings. Reconditioned Equipment.
Equipment which has been reconditioned must now be identified as “reconditioned”. The reconditioned equipment must be marked with the name, trademark or other marking which clearly identifies the company or organization that did the reconditioning. The date when the reconditioning was done must also be included.
An exception allows industrial occupancies, where conditions of maintenance and supervision ensure that only qualified persons service the equipment, to be exempted from this rule.
Approval of the reconditioned equipment by an inspection authority is not to be based solely on the equipment’s original listing. Re-listing of reconditioned equipment is not required, but the listing of the equipment when it was new may not cover the modifications made during reconditioning.
Normal servicing of equipment, where the equipment does not leave the facility, is not considered reconditioning or refurbishing.
The title to 110.21(A) has been changed from Manufacturer’s Markings to Equipment Markings. Markings for new and reconditioned equipment must be made on the equipment and must be able to withstand the environment where the equipment is located.
QUESTION 2: Which of the following is required to be marked on reconditioned equipment?
A. Details of reconditioning done.
B. Testing agency label.
C. Date of reconditioning.
D. Location of reconditioning.
3. 210.8(B) GFCI Protection for Personnel. Other Than Dwelling Units.
The requirements for GFCI protection of receptacles in other than dwelling units have been significantly expanded. Single phase receptacles rated 150 volts to ground or less and rated 50 amperes or less are required to have Ground-Fault Circuit-Interrupter protection. Three-phase receptacles rated 150 volts to ground or less and rated 100 amperes or less must also have GFCI protection. Unfinished basements and crawlspaces have been added to the list of locations requiring GFCI protection. There are now 10 areas requiring GFCI protection of receptacles in the other than dwelling locations covered by 210.8(B).
· Sinks – within 6 feet of the top inside edge of the bowl of the sink (CHANGE)
· Indoor wet locations
· Locker rooms associated with showers
· Garages and service bays, (other than vehicle exhibition halls/showrooms)
· Crawl spaces (NEW)
· Unfinished basements (NEW)
For example, a 30 ampere single phase 120/240 volt receptacle outlet for a clothes dryer in a motel laundry room installed within 6 ft. of a sink requires GFCI protection. A 240 volt rated single-phase 20 ampere receptacle for a sump pump installed in an unfinished basement or crawlspace will also require GFCI protection.
The number of accidental electrocutions of consumers has declined dramatically since GFCI protection was first introduced in the 1971 NEC. Expanding the protection to include more non-dwelling applications will increase safety. This is especially true for wet locations, unfinished basements, crawl spaces or other areas where working conditions may increase the potential for electric shock.
QUESTION 3: Which of the following receptacle outlets will require GFCI protection?
A. A 120/208 volt, 50 amp rated, 3-phase receptacle installed in an office.
B. A 120/240 volt, 30 amp rated, single-phase receptacle for a window unit air conditioner installed in an employee bathroom.
C. A 480 volt, 3-phase, 60 amp rated receptacle for an air compressor in a commercial garage.
D. A 240 volt, 20 amp rated, single-phase receptacle in the finished area of the basement.
4. 100 Field Labeled (as applied to evaluated products).
Field Labeled means:
Equipment or materials to which has been attached a label, symbol, or other identifying mark of an FEB (Field Evaluation Body) indicating the equipment or materials were evaluated and found to comply with requirements as described in an accompanying field evaluation report.
Field labeled is different than field inspections” made by 3rd party testing organizations. Field inspections, as described in 90.7, are part of the listing process, and can be done to determine if field installed equipment meets the standards of a listing agency.
Field labeled is an examination of equipment by a Field Evaluation Body to determine if the equipment or materials meet the requirements of a field evaluation report. It is not a listing label. The purpose of the field label is to certify that the equipment is safe and is ready for operation.
Field labeling will be used to certify equipment used in Large-Scale Photovoltaic (PV) Electric Supply Stations. Section 691.5, Equipment Approval, in the new Article 691 says equipment in Large-Scale Photovoltaic (PV) Electric Supply Stations can be approved for field installation by (1) Listing and labeling; (2) field labeling; and (3) if products are not available that comply with (1) and (2) then approval by engineering review validating that equipment has been tested to relevant standards or industry practice.
QUESTION 4: What term is used when a Field Evaluation Body has evaluated and marked equipment on a jobsite?
A. Approved Equipment.
B. Factory Approved.
C. UL listed.
D. Field Labeled.
5. 366.20 Auxiliary Gutters. Conductors Connected in Parallel.
New section 366.20 spells out the requirements for installing conductors in parallel in an auxiliary gutter. The conductors must be installed in groups consisting of not more than one conductor per phase, neutral, or grounded conductor. This grouping will minimize current imbalances due to inductive reactance.
The 2014 NEC did not address parallel conductors installed in one metal enclosure such as an auxiliary gutter. The new requirement for installing parallel conductors in an auxiliary gutter is similar to the requirement for installing parallel conductors in raceways.
Section 310.10(H)(3) requires that when installing parallel conductors in separate raceways each raceway must have the same number of conductors and have the same electrical characteristics.
Example: When installing a three-phase, four-wire feeder consisting of two conductors in parallel per phase, each of the two raceways must contain Phases A, B, and C, and the neutral.
NEC Section 300.20(A) also requires that conductors installed in ferrous metal raceways must be arranged to avoid the heating of surrounding metals by induction. Grouping each phase and the grounded conductor in separate groups will help prevent this induced heating of surrounding metal when parallel conductors are installed in auxiliary gutters.
QUESTION 5: When installing parallel conductors in an auxiliary gutter, which conductors are required to be in each group?
A. All conductors of the same phase only.
B. One phase conductor only and no neutral conductors.
C. All phase conductors only.
D. One conductor of each phase, neutral or grounded conductor.
6. 314.16(A) Number of Conductors in Outlet, Device, Junction Boxes, and Conduit Bodies. Box Volume Calculations.
Section 314.16(A) of the NEC now requires the volume taken up by barriers installed in a box to be considered when doing a box fill calculation. Installing a barrier in a box leaves less volume for other wiring components in the box but the added space for the barrier was not considered before. Each metal barrier not marked with its volume must be considered to take up 8.2 cm³ (1/2 in³) of volume and each nonmetallic barrier not marked with its volume must be considered to take up 16.4 cm³ (1.0 in³) of volume. The volume taken up by the barriers must be divided equally between each of the resulting spaces.
Example 1: A square box has a volume of 30.3 in³. A metal barrier inserted into the box creates two equal separate spaces. The volume of each space would be one half of the original 30.3 in³minus one half of the ½ in³volume taken up by the barrier.
30.3 in³ A · 2 = 15.15 in³ 15.15 in³ - .25 in³ = 14.9 in³
Example 2: A three gang box has 42 in³ of volume. Two nonmetallic dividers are installed to create three separate spaces. The volume of one of the outside spaces is 1/3 of the 42 in³ volume minus ½ of the volume taken up by one of the dividers.
1/3 x 42 in³ = 14 in³ 14 in³ - .5 in³ = 13.5 in³
The volume of the middle space is 1/3 of the 42 in³ volume minus the volume taken up by one whole divider (1/2 of a divider on each side).
1/3 x 42 in³ = 14 in³ 14 in³ – 1.0 in³ = 13 in³
QUESTION 6: How much volume must be considered for a metal barrier not marked with its volume?
A. ½ in³.
B. ¼ in³.
C. 1.0 in³.
D. ¾ in³.
7. 406.4(D)(5) General Installation Requirements. Replacements. Tamper-Resistant Receptacles.
The NEC includes requirements for specific types of receptacles in specific places. When a receptacle of a type that does not meet current NEC requirements is replaced, it is usually required to be replaced with the specific type required for that location. The most general requirement is for replacing non-grounding type receptacles with grounding type receptacles but similar rules apply where tamper-resistance receptacles are required in the current code. Tamper-resistance receptacles are currently required for new installations in dwelling units, guest rooms and guest suites of hotels and motels, in child care facilities and in other locations specified in Section 406.1 if the receptacles are of the nonlocking-type and the receptacles are rated 15- or 20-ampere 125- or 250-volt. Exceptions to this section apply if the receptacles are located in areas that cannot be reached by children.
The change in Section 406.4(D)(5) addresses replacements that are required to be tamper-resistance elsewhere in the NEC. It does not change where tamper-resistant receptacles are required in new installations. However, Section 406.12 includes an exception that says certain receptacles are not required to be tamper-resistant. Some of those exceptions are related to height or use of the receptacles. One of those exemptions recognizes that a non-grounding type receptacle that is replaced by another non-grounding type receptacle as allowed in 406.5(D)(2)(a) will not be tamper-resistant. So, to make the requirements and exceptions clearer, to make the code easier to use, and to eliminate any perception that the rules were contradictory, the exemption for non-grounding type receptacles was repeated in 406.4(D)(5). However, it was not added as an exception. Instead, 406.4(D)(5) now states the general requirement and then adds in the same sentence: “except where a non-grounding receptacle is replaced with another non-grounding receptacle”.
QUESTION 7: Assuming a receptacle is in an area where tamper-resistant receptacles are required in the current NEC, which of the following statements about replacing the receptacle with a tamper-resistant receptacle is true?
A. Receptacles must be replaced with whatever type of receptacle was removed.
B. Receptacles may be replaced with receptacles that are not tamper-resistant if a tamper-resistant cover is added.
C. Receptacles must be replaced with tamper-resistant receptacles except where a non-grounding receptacle is replaced with another non-grounding receptacle.
D. Replacement receptacles must always be tamper-resistant.
8. 625.40 Electric Vehicle Charging System. Electric Vehicle Branch Circuit.
The requirements for electric vehicle branch circuits have been relocated from 210.17 to a new section 625.40. The wording has also been revised to eliminate confusion over the number of outlets permitted on the electric vehicle branch circuit.
Each outlet installed for the purpose of charging electric vehicles shall be supplied by an individual branch circuit. (625.40)
This is a change from the previous language in 210.17 that referred to outlet(s) supplied by a separate branch circuit. The code is now clear that only one outlet is permitted on each individual branch circuit installed for the purpose of charging an electric vehicle. No other outlets are permitted on the branch circuit.
The term outlet includes both a receptacle outlet and equipment connected by permanent means. Both stationary and portable cord-and-plug connected electric vehicle charging systems are available. Electric vehicle charging is considered a continuous load for the purposes of Article 625. The individual branch circuit must be rated not less than 125% of the maximum charging load.
QUESTION 8: A new car dealer installs 2 electric vehicle charging systems rated 16 amperes each. Which one of the following branch circuit(s) is the minimum required?
A. One 40-ampere branch circuit.
B. Two 15-ampere branch circuits.
C. One 35-ampere rated branch circuit.
D. Two 20-ampere branch circuits.
9. 90.2(A) Scope. Covered.
In this important section about what the 2017/20 National Electrical Code covers, the removal of electrical conductors, equipment and raceways is now included. In the 2014 version of the NEC, only the installation of electrical conductors, equipment, and raceways was listed in the Scope. Now, the installation and removal of electric conductors, equipment, and raceways, as well as the installation and removal of signaling and communications conductors, equipment, and raceways; and optical fiber cables and raceways is part of the Scope of the NEC.
There are numerous sections in the National Electrical Code where the removal of conductors and cables is required. For example, Section 590.3(D) says, Temporary wiring shall be removed immediately upon completion of construction or purposes for which wiring was installed. Section 590.3(B) says, Temporary electric power and lighting installations shall be permitted for a period not to exceed 90 days for holiday decorative lighting and similar purposes.
Another example is Section 725.25, Abandoned Cables for Class 1, Class 2, and Class 3 Remote Control, Signaling, and Power-Limited Circuits, which covers the installation of computer and network cables outside of computer rooms. The accessible portion of abandoned Class 2, Class 3 and PLTC cables shall be removed. Where cables are identified for future use with a tag, the tag shall be of sufficient durability to withstand the environment involved.
A similar statement is made in Section 800.25 for abandoned cables used for communications circuits, including telephone wiring. If the cables are accessible (cables installed in conduit are not accessible) and the cables are not connected to equipment or identified for future use, then they must be removed.
The Scope of the 2017 National Electrical Code now covers the installation and removal of electrical conductors, equipment and raceways; signaling and communications conductors, equipment, and raceways; and optical fiber cables and raceways.
QUESTION 9: What is included in the Scope of 2017 National Electrical Code?
A. Only the installation of electric conductors.
B. The removal of electric conductors is not covered in the Scope of the 2017 NEC.
C. Both the installation and removal of electric conductors.
D. Only the removal of electric conductors.
10. 210.70(C) Lighting Outlets Required. All Occupancies.
The title of this section has been changed from Other Than Dwelling Units to All Occupancies. Utility rooms and basements have been added to the locations where lighting outlets are required when the space is used for storage or contains equipment that requires service such as heating units, water heaters, or pumps.
In all occupancies, a minimum of one lighting outlet is required for attics and underfloor spaces, utility rooms, and basements, that are used for storage or that contain equipment that requires service. A lighting outlet must be located at or near any equipment or appliance that requires servicing. If there is more than one piece of equipment in the space, more than one lighting outlet may be required.
For example, if a heating unit is located in one corner of a large basement and the water heater is 50 feet away, a lighting outlet is required at the heating unit and another lighting outlet is required at or near the water heater.
The lighting outlet(s) must be controlled by a wall switch located at the usual point of entry of servicing the equipment. A keyless lampholder equipped with a pull chain snap switch is not acceptable. Additional lighting controls at other locations are permitted, but not required.
QUESTION 10: A basement under a lawyer’s office is 80 ft. in length and contains a heating unit and a sump pump 60 ft. apart. How many lighting outlets are required?
A. No lighting outlets are required.
B. 3 lighting outlets.
C. 2 lighting outlets.
D. 1 lighting outlet.
11. 406.6(D) Receptacle Faceplates. Receptacle Faceplate with Integral Night Light and/or USB Charger.
A new Section 406.6(D) was added in the 2017 NEC. It is titled “Receptacle Faceplate (Cover Plates) with Integral Night light and/or USB Charger”. This addition is intended to address the use of cover plates for flush duplex receptacles that attach to the receptacle and include an integral night light or a Class 2 power supply with Class 2 USB output connectors, or both. The concern is that these devices may not be tested and may not meet appropriate safety standards. An ANSI/UL standard exists that includes reqs for such devices. So the reason for the new requirement is quite simple: Such devices should not be allowed unless they are tested and listed to ensure their safety, especially in combination with the receptacle to which they are attached.
The new requirement is that if a faceplate or cover plate includes a night light or a USB charger or both, the night light and/or USB connector and its power supply and circuitry must be an integral part of the cover plate and the assembly must be listed. USB power supplies or chargers alone are typically listed as information technology equipment (ITE) and according to Section 725.121(A)(4) are required to be listed if they are to be considered as Class 2 power supplies. By definition, the output of a Class 2 power supply is not a fire or shock hazard under normal but sometimes limited conditions. Power limitations of ITE equipment are usually even lower than other typical Class 2 sources. So the safety issue is mostly related to the power supply from the receptacle to the Class 2 source or the night light and the requirement that the Class 2 source itself be tested and listed.
These devices are likely sold as add-on devices that are installed by homeowners rather than being primarily sold to and installed by qualified electricians. But requirements for listing of electrical equipment in order to meet NEC requirements will often encourage retailers to stock and sell equipment that is recognized by the NEC over equipment that is not, and it will make qualified electricians more likely to be aware of the issue.
QUESTION 11: Which of the following statements about receptacle faceplates with integral USB chargers is true?
A. Faceplates with integral USB chargers are prohibited.
B. The USB charger and power supply must be part of the receptacle.
C. The assembly must be listed.
D. The USB power supply can be separate from the assembly if it is listed separately.
12. 210.11(C)(4) Dwelling Units. Garage Branch Circuits.
A new branch circuit has been added to the list of required branch circuits for dwelling units. At least one 20 amp rated 120-volt branch circuit shall be installed to supply receptacle outlets in a garage. A similar, but not identical requirement, was introduced in Section 210.52 of the 2014 NEC. Moving the requirement to Section 210.11(C) groups all of the required branch circuits for a dwelling unit in a single location. The garage receptacle branch circuit is not permitted to supply any other outlets with a single new exception provided for readily accessible outdoor receptacle(s).
The exception will allow any readily accessible outdoor receptacles including the required outdoor receptacles on the front and back of a dwelling and the receptacle for servicing heating and air conditioning equipment to be supplied by the garage receptacle branch circuit. Lighting outlets inside or outside of the garage are not permitted to be connected to the garage receptacle branch circuit.
Loads in residential garages have steadily increased over the years. Portable air compressors, electric tools, battery chargers, spare refrigerators and electric vehicles have become common items in the garage. Adding a requirement for a minimum of one 120-volt 20 ampere branch circuit for the garage receptacles should reduce the possibility of overloading the receptacle branch circuit.
QUESTION 12: Which of the following receptacles is NOT permitted on the required garage branch circuit?
A. A readily accessible outlet on an exterior wood deck.
B. An outdoor receptacle above an equipment platform accessible by portable ladder.
C. A readily accessible outdoor receptacle for servicing a heat pump.
D. The required outdoor receptacle on the front of a one-family dwelling.
13. 210.8 GFCI protection for Personnel.
Receptacle outlets within 6 ft. of a sink, and receptacle outlets within 6 ft. of a bathtub or shower stall still are required to have GFCI protection. What is new in the 2017 NEC is how to measure that 6 ft. distance.
The distance shall be measured as the shortest path the cord of an appliance connected to the receptacle would follow without piercing a floor, wall, ceiling, or fixed barrier, or passing through a door, doorway or window.
Typical small appliance cords used within 6 ft. of a sink, bathtub or shower stall are not longer than 6 feet in length. If the shortest path the cord will follow is greater than 6 feet, the appliance will remain outside of the wet conditions around the sink or shower, and GFCI protection is not required.
The 2017 NEC also changes the measurement for sink from the outside edge of the sink to the top inside edge of the bowl of the sink. Many sinks have raised bowls above the sink cabinet and this change will include those designs. For bathtubs and shower stalls the 6 feet is still measured to the outside edge.
For all receptacles inside bathrooms, as defined in the NEC, GFCI protection must be provided in accordance with 210.8, even if the receptacle is further away from the sink than 6 ft.
QUESTION 13: Which of the following 15 amp, 125 volt dwelling unit receptacles DO NOT require GFCI protection?
A. An ironing board receptacle located 6 ft. above the floor and 5 ft. diagonally from the inside top edge of the laundry sink bowl.
B. A wall receptacle installed 6 ft. 1 in. from the inside edge of a kitchen sink.
C. A receptacle 6 ft. measured diagonally from the outside edge of a shower.
D. A wall receptacle located 5 ft. measured around a corner from a wet-bar sink in the same room.
14. 210.52(G)(1) Dwelling Unit Receptacle Outlets. Garages.
Section 210.52(G)(1) has been revised to clarify that at least one receptacle outlet is required in each vehicle bay in a garage.
The 2014 NEC required a receptacle outlet “for each car space”, but did not specify a location. The 2017 NEC requires “at least one receptacle shall be installed in each vehicle bay”. The term car space was dropped in favor of vehicle bay. Garages are used for many types of vehicles, not just cars. The receptacle can be located on any wall in the vehicle bay, but there must be an outlet in each vehicle bay. The receptacle outlets serving the vehicle bay cannot be located more than 5-1/2 feet above the floor and must be in addition to any receptacles installed for specific equipment.
Clarifying that at least one receptacle outlet is required in each vehicle bay eliminates any question as to where the required receptacles should be placed. Receptacles located in each vehicle bay will typically be accessible for charging the battery of an electric vehicle or other vehicle service. A receptacle in each vehicle bay will also reduce the need for extension cords in the garage.
The requirement for a branch circuit to serve only the garage receptacles has been relocated to Section 210.11. In a major Code change, the 20-ampere garage receptacle circuit required in Section 210.11(C)(4) is now permitted to supply outdoor outlets outside the garage.
QUESTION 14: Which of the following is acceptable as the required garage receptacle(s)?
A. A receptacle installed in the vehicle bay 5 ft. above the floor.
B. A receptacle in a storage closet opening directly into the garage.
C. A receptacle for a clothes washer if installed in the garage.
D. A receptacle on the ceiling for the garage door opener.
15. 680.21(A) Swimming Pools, Fountains. Motors. Wiring Methods.
Two types of wiring methods are now permitted for pool pump motors. (1) Wiring that is located in a corrosive environment, as described in new section 680.14, and (2) wiring that is installed in noncorrosive environments.
Wiring installed in noncorrosive environments must comply with the general requirements found in Chapter 3. Wiring installed in a corrosive environment must be installed in rigid metal conduit, intermediate metal conduit, rigid polyvinyl chloride conduit or reinforced thermosetting resin conduit. MC cable listed for the location is also permitted.
From section 680.14, corrosive environments are “areas where pool sanitation chemicals are stored, as well as areas with circulation pumps, automatic chlorinators, filters, open areas under decks adjacent to or abutting the pool structure, and similar locations”. Any pool equipment, including pool pup motors, must be supplied with a wiring method which complies with the requirements for corrosive areas. Any wiring method used in a corrosive location must contain an insulated copper equipment grounding conductor sized in accordance with Table 250.122, but not smaller than 12 AWG.
Section 680.21 on Motors has been renumbered and the sections in the 2014 NEC about wiring on or within buildings, and in one-family dwellings have been deleted.
QUESTION 15: Which of the following wiring methods is permitted in a corrosive area of a swimming pool?
A. Flexible Metallic Tubing, Type FMT.
B. Rigid Polyvinyl Chloride, Type PVC.
C. Electrical Nonmetallic Tubing, Type ENT.
D. Electrical Metallic Tubing, Type EMT.
16. Article 411 Low-Voltage Lighting.
Article 411, Low Voltage Lighting, now restricts output voltages to 30 volts ac or 60 volts dc. Where wet contact is likely to occur, the voltage limits are 15 volts ac or 30 volts dc.
The reference to Class-2 power sources in the title of the Article was deleted because a Class-2 power source at 60 volts dc is limited to an output of 100VA, or 1.7 amps. Most low voltage lighting systems require more than 1.7 amps.
Section 411.4(A) was revised to exclude systems with insulated conductors from the requirement that “lighting systems operating at 30 volts or less shall be listed as a complete system”. In the 2014 NEC, Section 411.4(A) conflicted with Section 411.4(B) that allows a lighting system to consist of separate listed parts. The new wording clarifies that systems with bare conductors must be listed as complete systems, but systems with insulated conductors may consist of separate listed parts. The revised rules in Article 411 are straightforward:
1. Low voltage systems are limited to 30 volts AC and 60 volts DC unless wet contact is likely to occur where the voltages are 15 volts AC and 30 volts DC.
2. The maximum current output of a power supply is 25 amps.
3. Bare conductor systems must be listed as a complete system and insulated conductor systems may be made up of listed components.
QUESTION 16: What is the maximum output voltage for an AC low voltage lighting source?
A. 24 Volts
B. 30 Volts
C. 12 Volts
D. 60 Volts
17. 210.52(B)(1) Exception No. 2. Dwelling Unit Receptacle Outlets. Small Appliances. Receptacle Outlets Served.
Exception No. 2 to 210.52(B)(1) is no longer limited to refrigeration equipment. An individual 15 ampere branch circuit can now supply a receptacle for a specific appliance in kitchens and similar areas of dwelling units. An individual branch circuit cannot supply more than one appliance.
Receptacle outlets in the kitchen, dining room, breakfast room, pantry or similar room in a dwelling are generally supplied by one of the two or more 20-amp small appliance branch circuits required by 210.11(C)(1). Two exceptions to the 20-amp minimum requirement are provided in 210.52(B)(1). Exception No. 1 is unchanged.
Exception No. 2 previously allowed a 15-amp individual branch circuit to be installed for refrigeration equipment only. Individual branch circuits serving other specific appliances were required to meet the 20-amp minimum rating for a small appliance branch circuit. Individual 15-amp branch circuits are now allowed for a specific appliance. The receptacle installed for a specific appliance must be in addition to the receptacles required by 210.52. Allowing a separate 15-amp circuit for the refrigerator was logical because it removed a significant load from one of the 20-amp small appliance branch circuits. The same logic applies to other appliances. For example, installing a 15-amp individual branch circuit for a 10-amp rated microwave reduces the potential load on one of the 20 ampere small appliance branch circuits by 50%.
QUESTION 17: In a dwelling kitchen, which one of the following is NOT permitted to be supplied by a 15-ampere individual branch circuit?
A. Two receptacles for a range hood and microwave oven.
B. A receptacle for an 8-amp garbage disposal.
C. A receptacle for a 9-amp Espresso machine.
D. A receptacle for a cord and plug connected 5-amp range hood.
18. 310.15(B)(3)(c) Tables. Adjustment Factors. Raceways and Cables Exposed to Sunlight on Rooftops.
Table 310.15(B)(3)(c) has been removed from the NEC and replaced with a new simplified method for how conductor ampacities must be calculated when installed in cables or raceways on or above rooftops exposed to direct sunlight.
Specifically, the 2017 NEC requires that raceways and cables be installed a minimum distance of 7/8 of an inch above the rooftop. When the minimum distance is less than 7/8 of an inch, the ambient temperature must be increased by 33°C (60°F) for ampacity adjustment purposes.
Example: Three No. 4 copper THW conductors are installed in a raceway outdoors directly on a rooftop exposed to direct sunlight. The ambient outdoor temperature maximum is 98°F. Because the raceway is directly on the rooftop, 60°F must be added to the 98°F ambient for derating purposes. (98° + 60°=158°). The derating factor from Table 310.15(B)(2)(a) for 158°F is 33%. The ampacity of a No. 4 copper THW from table 310.15(B)(16) is 85 Amps. 85 Amps x .33 = Amps. The ampacity of the No. 4 copper THW conductors under those conditions of use is 28 amps. If the raceway was installed with a clearance of at least 7/8 of an inch above the rooftop the derating factor would be based on an ambient of 98°F with no 60°F increase required. The ampacity adjustment factor from table 310.15(B)(2)(a) would be 88%. 85 Amps x .88 = 74.8 Amps.
QUESTION 18: The NEC generally requires that raceways on rooftops exposed to direct sunlight be raised ________ above the rooftop.
A. 7/8 inch.
B. 4 inches.
C. ½ inch.
D. 3 inches.
19. 406.3(E) Receptacle Rating and Type. Controlled Receptacle Marking.
All receptacles of the ordinary straight-blade (non-locking) type that are rated 125-volt, 15- or 20-ampere, are required to be marked if they are controlled by an automatic control device. These receptacles could be controlled by energy management or building automation controls to activate or deactivate the receptacle or they could be controlled by some other automatic control device such as an automatic timer or occupancy sensor.
The marking on the controlled receptacle must be on the face of the receptacle, not on the cover plate, and must be visible after installation. If a duplex or multiple receptacle device is used, the marking must indicate which contact device or devices are automatically controlled.
The 2014 NEC required a similar marking, but was a symbol only, a symbol that is widely used to indicate a power switch, or on/off. The intent of the symbol was that the marking be clear to non-English speakers. Unfortunately, that symbol was not universally recognized or understood. The 2017 NEC requires that the word “Controlled” be added to the symbol. The controlled receptacle itself must be marked, not just the receptacle outlet as was allowed in the 2014 NEC. So if only the top receptacle of a duplex outlet is controlled, the marking must indicate it is the one being controlled.
The primary concern behind this change was that a clear message be provided for people using a receptacle if the receptacle may not always be energized or activated. Having power available at all times may be important or critical in some applications, and it should be obvious to a user if a receptacle is likely to be deactivated by some automatic means. Another concern is that the marking should indicate precisely which receptacle is controlled. Markings on cover plates may be lost when cover plates are changed or removed temporarily. For example, a typical cover plate can be installed in either direction (up/down or left/right) and when the cover is removed to change a wall finish, the plate could easily be reinstalled in the wrong position. So the new requirement is that the marking be directly on the receptacle face.
This requirement does not apply to wall-switch controlled receptacles used as lighting outlets in some rooms of dwelling units as permitted in Section 210.70.
QUESTION 19: Which of the following statements about a controlled receptacle is true?
A. The required marking is the same as in the 2014 NEC.
B. The marking may be on the receptacle or on the cover plate.
C. The marking must be on the receptacle face.
D. The universal power symbol is well recognized so no additional marking is required.
20. 445.13(B) Generators. Ampacity of Conductors. Overcurrent Protection Provided.
This change adds a new subsection (B) that is intended to clarify when taps can be made on the load side of generators that are equipped with listed overcurrent protective devices. The overcurrent device could consist of a current transformer and overcurrent relay, as well as a circuit breaker, fuse or other listed overcurrent protective device.
With this change, it is clear that the conductors on the load side of a listed overcurrent protective device will be treated as feeders and will be permitted to be tapped under the “tap rules” of 240.21(B). This has been a common practice, but Article 445 was not clear on whether it was permitted or not.
However, this permission for tap conductors only applies to larger generators where field-wiring connection points have been provided on the load side of a listed overcurrent protective device. Smaller generators, especially portable generators, are typically connected by cord and plug, so the tapped conductors are not permitted for portable generators rated 15kW or less where terminals for field wiring connections are not accessible.
The previous rule that is now 445.13(A) only addressed the size or ampacity of the conductors from the generator to the first distribution device or devices that contain an overcurrent device. That rule was changed to clarify that the conductors in question are only those from the output terminals of the generator, not to all conductors that are internal to the generator.
QUESTION 20: When are taps NOT permitted when they are on the load side terminals of a generator with a listed overcurrent device?
A. When the generator is not cord-and-plug connected.
B. When field wiring terminals are accessible.
C. When field wiring terminals are not accessible.
D. When the generator is 15kW or more.
21. 210.8(B)(10) GFCI Protection for Personnel. Other Than Dwelling Units. Basements.
GFCI protection for personnel is now required for receptacles in unfinished basements in office buildings, schools, industrial facilities and other non-dwelling unit locations. An unfinished basement is any unfinished portions or areas of the basement not intended as habitable rooms.
GFCI protection is required for single phase receptacles rated 150-volts to ground or less and not more than 50 amperes. Three phase receptacles rated 150-volts to ground or less and 100 amperes or less also require GFCI protection. All receptacles within these ratings in unfinished basements, including receptacles that may not be considered readily accessible must have GFCI protection.
GFCI protection has been required for receptacles in unfinished basements in dwellings for many years. Similar electrocution hazards exist in unfinished basements regardless of the type of occupancy. The unfinished portions of basements are often poorly illuminated, damp, and contain equipment that require periodic service. Extension cords and portable lights are often used in these areas. Providing GFCI protection for receptacles in unfinished basements will substantially reduce the electrical shock hazard for workers in these areas.
QUESTION 21: In the unfinished portion of a basement at a hospital, which one of the following does NOT require GFCI protection?
A. A 277-volt, single phase, 20 ampere lighting branch circuit.
B. A 120/208-volt, three phase, 20 ampere receptacle for a sump pump.
C. A 125-volt, single phase, general purpose receptacle.
D. A 120/208-volt, single phase, 30 ampere receptacle.
22. 250.52(B)(3) Grounding Electrodes. Not Permitted for use as Grounding Electrodes.
In general, bonding all available electrodes together to form a single grounding electrode system for a building is a good idea, but there are some underground systems and structures, such as underground metal gas piping, that are not intended to be used as grounding electrodes. Swimming pool structures covered by 680.26(B)(1) and (B)(2) are also now included in the list of systems and material in 210.52(B) that shall not be used as grounding electrodes.
(1) Metal underground gas piping systems.
(3) The structures and structural reinforcing steel described in 680.26(B)(1) and (B)(2).
Article 680 requires metal parts of a swimming pool and the perimeter surfaces around the pool to be bonded together either by structural steel or by No. 8 bare solid copper conductors. This equipotential bonding protects people using the pool from electrical shock by reducing voltage gradients in the pool area. It is not intended to be used as a grounding electrode for the electrical service.
Using the bonding system of a swimming pool or similar structure as part of the grounding electrode system could introduce current from the electrical system into the earth near the swimming pool. In addition, lightning strikes or unintentional contact between high-voltage lines may result in temporary currents in the grounding electrode system. Any of these conditions could pose a life safety hazard if swimming pool structures are used as a grounding electrode for the electrical system.
QUESTION 22: Which one of the following is permitted to be used as a grounding electrode?
A. An aluminum rod 10 ft. in length.
B. 20 ft. of underground metal gas piping.
C. 10 ft. of underground metal water pipe.
D. Structural reinforcing steel in a concrete swimming pool.
23. 680.25 Permanently Installed Pools. Feeders.
The 2014 NEC required feeders on the supply side of panelboards that supplied branch circuits to swimming pools to have an insulated equipment grounding conductor. This was a big problem in dwellings if a homeowner wanted to install a swimming pool and use an existing panelboard to feed pool equipment. If the existing feeder from the service to the panelboard did not have an insulated equipment grounding conductor, the homeowner could not use that panelboard to supply the pool equipment. The homeowner would either have to supply the pool equipment as branch circuits from the service equipment, or install a new feeder to the pool panelboard.
The 2017 NEC has corrected this situation by allowing feeders which are installed in non-corrosive environments, and are on the supply side of panelboards which feed pool equipment, to be wired with any method found in Chapter 3. This means that feeders which are in noncorrosive areas can be installed using cables that do not have an insulated equipment grounding conductor, such as SER cable.
Feeders that are in corrosive areas, and are on the supply side of panelboards supplying branch circuits for pool equipment, must have an insulated equipment grounding conductor sized in accordance with Table 250.122, but not smaller than 12 AWG. For example, the minimum size of an insulated copper equipment grounding conductor for a 60 amp feeder in a corrosive location would be a No. 10 AWG per Table 250.122, for a feeder protected at 100 amps the minimum size copper equipment grounding conductor would be No. 8 AWG, and a No. 6 AWG copper would be required for a feeder protected at 200 amps.
These same types of feeders in corrosive areas can only be installed in rigid metal conduit (RMC), intermediate metal conduit (IMC), rigid polyvinyl chloride conduit (PVC), and reinforced thermosetting resin conduit (RTSC). Liquidtight flexible nonmetallic conduit is also permitted.
QUESTION 23: What is the minimum size equipment grounding conductor to a 100 amp panelboard that is located in a corrosive area and supplies branch circuits to pool equipment?
A. No. 12 AWG.
B. No. 10 AWG.
C. No. 6 AWG.
D. No. 8 AWG.
24. 110.9 Interrupting Rating.
Equipment that is intended to interrupt current at fault levels must be capable of interrupting the highest level of fault current that is available. For example, if a circuit breaker is installed at a location in an electrical system where the available fault current is 50,000 amperes, it must be capable of safely interrupting at least 50,000 amperes.
The 2014 NEC stated this requirement by saying the equipment had to have an interrupting rating “sufficient for the current that is available at the line terminals of the equipment”. The phrase “sufficient for”was changed to “at least equal to”. The 2017 NEC now says that the interrupting rating must be “at least equal to the current that is available at the line terminals of the equipment”. This change brings more clarity to the requirement since the expression “sufficient for” was too vague.
The same change was made for equipment intended to interrupt current at something other than fault levels. For example, a switch intended to interrupt a current of 100 amperes must be rated to interrupt a current of 100 amperes or greater. The 2014 NEC stated that the switch needed to have an interrupting rating “sufficient for the current that must be interrupted”. The 2017 NEC states that the switch must have an interrupting rating “at least equal to the current that must be interrupted”.
QUESTION 24: A circuit breaker is installed at a location where the fault current available on the line side is 32.545 amps. The circuit breaker must have an interrupting rating of ____________.
A. No more than 32.545 amps.
B. 32.545 amps or more.
C. 32.545 amps or less.
D. 32.545 amps x 125%.
25. 210.70(A)(2) Lighting Outlets Required. Dwelling Units. Additional Locations.
If the lighting outlet in an interior stairway in a dwelling unit is controlled by a dimmer switch, the full range of dimming control must be available at all switch locations.
For interior stairways in dwelling units with six or more risers, the NEC requires a wall switch at each floor and at each landing level that includes an entryway. The intent is for someone entering the stairs to be able to turn on the stairway luminaire(s). This is usually accomplished by the use of three-way switches or a combination of three and four-way switches. Automatic control of stairway lighting is also an option.
The increasing use of dimmer switches to control stairway lighting results in a range of possible illumination levels in stairways. This can create a situation where there is insufficient lighting to safely navigate the stairs. According to the National Safety Council over 20,000 people died from falls at home in 2014. Many of these falls occurred on stairs.
The 2017 NEC requires that when dimmer switches are used to control stairway lighting outlets, the full range of dimming control must be available at each switch location. This will enable anyone entering the stairway at any floor level to fully illuminate the stairs.
For example, a two story house has a stairway with one lighting outlet over the stairs. The lighting outlet is controlled by a three-way switch at the top of the stairs and a second three-way switch at the bottom of the stairs. If a dimmer switch is installed at the bottom of the stairs and set to the lowest lighting level, it is impossible for someone entering the stairway from the second floor to properly illuminate the stairs. There must be a dimmer switch installed at both the first and second floor levels in order to provide the capability to fully illuminate the stairway from either switch location.
QUESTION 25: If dimmer switches are installed to control stairway lighting in a three story dwelling unity with a single stairway and one wall switch at each floor level, how many dimmer switches are required?
A. 3 dimmer switches are required.
B. 1 four-way switch and 2 dimmer switches.
C. 2 three-way switches and 1 dimmer switch.
D. 2 dimmer switches and 2 three-way switches.
26. 314.27(E) Outlet Boxes. Separable Attachment Fittings.
A new type of connection is now permitted at outlet boxes. Separable Attachment Fittings are a pin and sleeve type connection that can be used to attach luminaires or ceiling fans to outlet boxes. The mounting support is installed in the ceiling box and a mating attachment fitting is made into the luminaire or fan. The luminaire or fan is then attached to the receptacle with a twist lock mechanism. Listed locking support and mounting receptacles must be used with compatible attachment fittings to ensure the equipment is securely supported.
The listed combination of receptacle and separable attachment fitting must be identified and installed within the weight limits of the listing. If the supporting receptacle is installed in the outlet box it must be included in the box fill calculation.
The definition of a “receptacle” in Article 100 has been revised to recognize the type of receptacle used with these fittings. A receptacle is a contact device installed at the outlet for the connection of an attachment plug, or for the direct connection of electrical utilization equipment designed to mate with the corresponding contact device.
The new way of attaching luminaires or ceiling fans to ceiling boxes with separable attachment fittings will simplify the final trim out. With the receptacle wired into the outlet box, the luminaire or fan can be installed quickly and easily.
QUESTION 26: Which of the following is a requirement for a Separable Attachment Fittings used with a box to support a luminaire?
A. Separable attachment fittings may not be used in dwelling units.
B. Separable attachment fittings must be of the locking type.
C. Separable attachment fittings must be approved for at least 50 pounds.
D. Separable attachment fittings may be used with metallic boxes only.
27. 680.14 Swimming Pools, Fountains. Corrosive Environment.
Section 680.14 Corrosive Environment is a new Section in the 2017 NEC. It describes the corrosive areas near a swimming pool and lists the wiring methods that are permitted in a corrosive area.
Section 680.14(A) describes locations considered to be a corrosive environment.
“(A) General. Areas where pool sanitation chemicals are stored, as well as areas with circulation pumps, automatic chlorinators, filters, open areas under decks adjacent to or abutting the pool structure, and similar locations shall be considered to be a corrosive environment”.
The air in these areas is filled with corrosive gasses such as acid, chlorine and bromine which can cause corrosion and eat away at equipment, conduit and wiring.
Section 680.14(B) specifies acceptable wiring methods when installed in a corrosive environment.
“(B) Wiring Methods. Wiring methods in the areas described in 680.14(A) shall be listed and identified for use in such areas. Rigid metal conduit, intermediate metal conduit, rigid polyvinyl chloride conduit, and reinforced thermosetting resin conduit shall be considered to be resistant to the corrosive environment specified in 680.14(A)”.
RMC, IMC, PVC, and RTRC are the only wiring methods permitted in corrosive areas where swimming pool chemicals may damage conduit. This includes conduit runs to pool pumps, pool filters, pool heaters, and pool chlorinators.
When wiring methods are not installed in corrosive environments as described in Section 680.14, such as an indoor feeder to a swimming pool panelboard, the wiring methods are not restricted to RMC, IMC, PVC, and RTRC. Other types of cable, conduit and tubing found in Chapter 3 can be used.
QUESTION 27: Which wiring method is permitted for swimming pool wiring located in a corrosive area?
A. Electrical Metallic Tubing: Type EMT.
B. Rigid Polyvinyl Chloride Conduit: Type PVC.
C. Flexible Metallic Tubing: Type FMT.
D. Electrical Nonmetallilc Tubing: Type ENT.
28. 100 Accessible, Readily. (Readily Accessible).
To be considered readily accessible, equipment must located such that it can be “reached quickly” for operation or inspection by “those to whom ready access is requisite” without the need to move or climb over obstacles or use a portable ladder. It should be noted that not everyone in a building has a requisite need to access the electrical equipment. For example, the patients in a hospital or the students in a school do not have any need to access the electrical panels.
The 2014 NEC states that, if a tool has to be used to gain access to equipment, the equipment is not considered readily accessible. For example, if a screwdriver is required to remove a panel to inspect the connections for a hot tub pump, the connections are not considered readily accessible. The 2017 NEC added the phrase “other than keys” to clarify that keys are excluded from what might be considered a tool when applying this definition. So a panelboard that is locked and requires a key to open is still considered readily accessible as long as qualified individuals have the key.
The 2014 NEC stated that having to “climb over” an obstacle to get to the equipment meant that it was not “readily accessible”. The 2017 NEC expanded the phrase to read “climb over or under”, so having to climb over or under an obstacle renders the equipment not readily accessible.
A new informational note gives background information on equipment requiring keys to access the equipment in “controlled or supervised” locations.
QUESTION 28: When is equipment NOT considered to be readily accessible?
A. If the equipment is located more than 50 feet away from other electrical equipment.
B. If climbing under ductwork is required to reach the equipment.
C. If permanent steps must be climbed to reach the equipment.
D. If a key is required to access the equipment.
29. 600.4(B) Electric Signs and Outline Lighting. Markings. Signs with a Retrofitted Illumination System.
Many fluorescent lighted signs are being retrofitted with light-emitting diodes (LED’s). New Section 600.4(B) requires markings to be placed on the sign stating the illumination system has been replaced. The marking must include the retrofit kit provider and installers name, logo or unique identifier.
When retrofitted tubular LED lamps are powered by existing fluorescent lamp sockets in the sign, an additional label is required that alerts service personnel the sign has been modified. The label must include language warning technicians not to install fluorescent lamps. This label must be visible during relamping and comply with Section 110.21(B), Field-Applied Hazard Markings.
Once a fluorescent luminaire has been retrofitted to work with tubular LED’s, if fluorescent tubes are installed in the modified luminaire, the fluorescent lamps could explode. The new requirement to install a warning label should prevent an installer from being injured by exploding fluorescent lamps.
QUESTION 29: A retrofitted sign must include marking with the name, logo or unique identifier of the kit supplier and the ___________?
C. Utility company.
30. 110.14(D) Electrical Connections. Installation.
New Section 110.14(D) requires the use of a “calibrated torque tool” to assure the terminal connecting devices for electrical connections will be torqued to the manufacturer’s requirements.
Terminal connecting devices must be torqued to the listed or labeled value given by the manufacturer. Common practice has been to use a standard wrench or screwdriver to torque the connection until it felt tight enough. If a calibrated torque tool is not used, there is no way of knowing if the connection is actually torqued to the correct value. In fact, studies have shown that well over half of field connections are not correctly torqued.
A calibrated torque tool is not required if the manufacturer “has provided installation instructions for an alternative method of achieving the required torque”. An example of such an alternative method is a single-use tool that bends or breaks when the proper torque has been achieved. When doing a final inspection of an electrical installation, the AHJ will not be able to know if a “calibrated torque tool” was actually used. But the inspector can ask for the equipment manufacturer’s installation instructions and compare the torque values of the actual termination with the required values.
QUESTION 30: When must a calibrated torque tool be used?
A. While the AHJ is present.
B. When the manufacturer gives the torque values in the instructions.
C. When installing all terminals.
D. When terminating all copper or aluminum conductors.
31. 210.52(C)(3) Countertops and Work Surfaces. Peninsular Countertop Spaces.
The way peninsular countertop spaces are measured has changed. Instead of measuring from the connecting edge, a peninsular countertop must be measured from the connected perpendicular wall, 210.52(C)(3). At least one receptacle must still be installed at all peninsular countertop spaces with a long dimension of 24 in. or greater and a short dimension of 12 in. or greater. The new rule will change the way receptacles are located to serve peninsular countertop spaces.
For example, in the 2014 NEC a peninsular countertop space 24 in. wide extending less than 12 in. from the connecting edge of a wall countertop did not require a receptacle outlet because the measurement was taken from the connecting edge. A peninsular space extending out 12 inches or more from a wall countertop required a receptacle on the peninsula. A receptacle for the wall countertop could not serve the peninsular countertop space.
In the 2017 NEC a 24 in. wide countertop extending out 10 in. from the edge of a 24 in. wide wall countertop has a long dimension of 34 in. measured to the connected perpendicular wall instead of 10 in. measured to the connecting edge. A receptacle is required to serve this space. A wall receptacle located at the peninsular space is acceptable.
The intent of changing the way peninsular countertops are measured is to allow wall receptacles to count as the required receptacle for peninsular countertops. Since only one receptacle is required for a peninsular countertop, even if the peninsular was 10 ft. long, but had a wall receptacle installed at one end, no additional receptacle outlets would be required because the wall receptacle counts as the required peninsular receptacle.
Peninsular countertops are often broken into separate countertop spaces by a sink or rangetop. Each countertop space created must then be measured separately. Any peninsular countertop space with a long dimension of 24 in. or greater and a short dimension of 12 in. or greater requires at least one receptacle outlet.
QUESTION 31: A peninsular countertop is 24 in. wide, extends out 12 in. from the edge of the wall countertop, and measures 36 in. from the connected perpendicular wall. What is the long dimension of the countertop space?
A. 60 in.
B. 12 in.
C. 24 in.
D. 36 in.
32. 250.64 Grounding Electrode Conductor Installation.
The rules for the installation and protection of grounding electrode conductors have been simplified.
A No. 6 AWG or larger copper or aluminum grounding electrode conductor is permitted to be run unprotected on the surface of a building unless exposed to physical damage. The grounding electrode conductor must be securely fastened in place and bare aluminum or copper clad aluminum conductors are not permitted to be used in direct contact with masonry or the earth.
Grounding electrode conductors, No. 6 AWG or larger that are exposed to be physical damage and all grounding electrode conductors smaller than No. 6 AWG must be protected by cable armor or by rigid metal conduit (RMC), intermediate metal conduit (IMC), rigid PVC conduit, reinforced thermosetting resin conduit Type XW (RTRC-XW), or electrical metallic tubing (EMT).
Grounding electrode conductors and grounding electrode bonding jumpers in contact with the earth are not required to meet the cover requirements of Table 300.5, but are required to be buried or protected if exposed to damage. For example, a No. 6 AWG grounding electrode bonding jumper between two ground rods must be buried or protected to avoid damage from lawn mowers or other ordinary maintenance activities. A minimum burial depth is not stated.
Bonding jumpers from grounding electrodes can be connected to an aluminum or copper busbar if the busbar is at least ¼ in. thick x 2 in. wide and is long enough to accept the number of terminations necessary to connect all of the bonding jumpers in the installation.
QUESTION 32: A No. 6 AWG solid copper grounding electrode conductor from a residential service to a ground rod is exposed to physical damage and run on the building surface. Which one of the following provides acceptable physical protection?
A. Nonmetallic flexible conduit.
B. No protection required when run on building surface.
C. Electrical nonmetallic tubing (ENT).
D. Rigid PVC conduit.
33. 690.47 Solar Photovoltaic (PV) Systems. Grounding Electrode System.
This section was completely rewritten and simplified. The revised section is divided into two parts, Section 690.47(A) that covers when a grounding electrode system is required, and Section 690.47(B) that permits the use of additional electrodes directly connected to an array frame or structure and refers to Article 250 to determine if an array frame or structure qualifies as a grounding electrode.
The previous version of this section included five slightly different scenarios for which grounding electrode system would be required. Those requirements have been simplified to a single rule that says a grounding electrode is required for any building or structure used to support a PV array. The rule also addresses the connection of PV array equipment grounding conductors to the grounding electrode system including rules for both solidly grounded systems and systems that are not solidly grounded. Generally, all equipment grounding conductors will be required to be connected to the grounding electrode system through the ordinary methods of equipment grounding in Article 250.
An informational note explains that most systems installed in recent years have been functional grounded systems, not solidly grounded systems. Such systems are permitted to make a connection to ground for grounded conductors using the equipment grounding conductor for the output of the PV system and using connections to associated grounded distribution equipment rather than by connecting directly to any electrode with a grounding electrode conductor. This is a significant change in the way grounding of PV systems is understood to be done and is an important reason for the addition of functional ground systems in 2017. It has no effect on the equipment grounding connections between arrays or structures which still also require a direct or indirect connection to a grounding electrode. However, the recognition that many systems are grounded through the equipment grounding conductors for the modules rather than through grounding electrode conductors means that grounding electrode conductors are not required for grounding of such systems.
QUESTION 33: When is a grounding electrode required for PV Systems?
A. When additional electrodes are connected directly to a frame or structure.
B. When any building or structure is supplied by a PV system.
C. When any building or structure supports a PV array.
D. When an equipment grounding conductor is not present.
34. 110.26(A)(4) Working Space. Limited Access.
Working space around electrical equipment is required to allow qualified individuals who are servicing the equipment enough room to safely do their job. If the equipment will required “examination, adjustment, servicing, or maintenance while energized” clear space around the equipment is required.
Some equipment like duct heaters or air handlers are located in spaces with limited access. New section 110.26(A)(4) addresses the required workspace and access to such equipment.
Earlier editions of the NEC did not make allowances for or give specific rules for equipment located in spaces with limited access.
Now, if the equipment is located above a lay-in ceiling a minimum of a 22 in. x 22 in. opening is required for access. If the equipment is located in a crawl space a minimum of a 22 in. x 30 in. access opening is required. The width of the working space may not be less than 30 inches or the width of the equipment whichever is greater. Doors on the equipment must be able to be opened at least 90 degrees.
The minimum depth of the space in front of the equipment may not be less than what’s given in Table 110.26(A)(1).
The minimum height of the working space in front of the equipment is “the height necessary to install the equipment in the limited space”. A horizontal ceiling structural member or access panel is permitted inside the defined work space.
QUESTION 34: What are the minimum dimensions required for the opening to access equipment located above a lay-in ceiling?
A. 22 in. x 22 in.
B. 22 in. x 30 in.
C. 22 in. x 24 in.
D. 24 in. x 24 in.
35. 210.52(D) Dwelling Unit Receptacle Outlets. Bathrooms.
Finding the proper place to install a receptacle outlet in a bathroom can be challenging. Receptacles must be installed on the wall adjacent to the basin and within 3 ft. of the outside edge of the basin per the NEC Section 210.52(D). There is often a mirror over the basin countertop that eliminates installing the outlet on the wall above the basin. One option is to install a receptacle in the countertop using a receptacle outlet assembly “listed for use in countertops” (2017 NEC). Another option is to locate the receptacle on the wall or cabinet below the countertop.
The 2014 NEC did not permit the required bathroom receptacle to be located more than 12 in. below the top of the basin. Simple enough to do with a conventional flush mounted basin in a countertop, but the increased popularity of basins with raised bowls created challenges in meeting the 12 in. maximum. A basin with an 8 in. raised bowl above the countertop leaves only a 4 in. space for the receptacle. The exact choice of the basin to be used may not even be known until the last minute or may change. If the basin is replaced with a different style in the future, does that mean the receptacle should be re-located?
It is much more practical to locate the receptacle relative to the countertop as the height of the countertop is less likely to change. The 2017 NEC allows the 12 in. measurement to be made from either the top of the basin or the basin countertop. For a pedestal or wall-hung sink, measure down from the top of the basin. If the basin is installed in a countertop, the receptacle is permitted to be located not more than 12 in. below the top of the basin countertop.
QUESTION 35: Which of the following meet the bathroom receptacle requirement?
A. A receptacle located 24 in. below the top of a pedestal sink.
B. A receptacle located on the wall 4 ft. from the outside edge of the basin.
C. A receptacle located on a non-adjacent wall 5 ft. from the basin.
D. A receptacle located on the side of the basin cabinet 12 in. below the countertop.
36. 310.15(B)(7) Tables. Single-Phase Dwelling Services and Feeders.
The conductor size for ungrounded single-phase dwelling services and feeders that are supplied by a 208Y/120 volt, three phase system can now be calculated at 83% of the dwelling load, just like services and feeders supplied by a 240/120 system. In order to qualify for this reduced conductor sizing, the service or feeder must carry 100% of the load for the dwelling.
This change can be widely applied when installing feeders to individual apartments in an apartment complex that is supplied by a 208Y/120 volt system. In the 2014 NEC, any two ungrounded conductors from the three-phase system supplying a single apartment would have to be selected from Table 310.15(B)(16). In the 2017 NEC, the ampacity of the two ungrounded feeder conductors can be adjusted to 83% of the calculated load on the dwelling unit. For example a 200 Amp feeder could be installed using conductors with an ampacity of only 166 Amps. (200 x .83 – 166).
If the feeder is supplied from a 208Y/120 Volt system the grounded conductor is not allowed to be smaller than the ungrounded conductors like it is for a 240/120 volt feeder. With a 240/120 volt system the currents on line “A” and line “B” are 180 degrees out of phase. If the current on line “A” is 75 amps and the current on line “B” is 75 amps, the neutral current will be 0 amps. With a single phase feeder taken from a 208Y/120 Volt system the currents on line “A” and “B” are 120 degrees out of phase. If the current on line “A” is 75 amps and the current on line “B” is 75 amps, the neutral current will also be 75 amps. Therefore ne reduced neutral is allowed for a feeder taken from a 208Y/120 Volt system.
QUESTION 36: A 208Y/120 volt three wire, 100 Amp feeder serves an individual apartment in a 12 unit apartment building. The service to the building is a 208Y/120 Volt three phase system. What is the minimum ampacity of the feeder conductors?
A. 80 Amps.
B. 83 Amps.
C. 100 Amps.
D. 125 Amps.
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