Journeyman Electrician - Test 1 - 2014 NEC

Section 210.64 indicates the required receptacle is to be installed within 50 feet of the electrical service equipment. This rule was established because at service equipment, there is sometimes a need for connecting portable electrical data acquisition equipment for the qualitative analysis of the electrical system. Also, test equipment is frequently used for monitoring and servicing electrical equipment about service areas.

You will find this definition in Article 100 of the NEC. To get a better understanding of ampacity, perhaps we might consider it as current-carrying capacity, or the maximum amperage a conductor can carry continuously without damaging the conductor and/or its insulation. When determining the ampacity of a conductor, or sizing a conductor, some factors needed to be taken into consideration are, the ambient temperature, the number of current-carrying conductors contained in the raceway or cable, the temperature rating of the terminations and the environment the conductor will be subject to.

As per Section 502.10(B)(4) boxes and fittings need to be dusttight to prevent combustible dust from entering dust-ignitionproof enclosures through the raceway or boxes.

Section 300.5(B) requires that the inside of all raceways and enclosures installed underground be classified as a wet location because water and moisture may enter the raceway and condensation may occur. Insulated conductors installed in such locations must be listed for use in wet locations.

To solve this problem, first locate the wire size on the left side of Table 310.15(B)(16) and look to the right under the copper THW column, with a temperature rating of 75C, and note the ampacity of the wire is 150 amperes. The table is based on an ambient temperature of 86C and not more than three current-carrying conductors in the raceway. This question states four (4) current-carrying conductors are in the raceway so we must apply the adjustment factor as shown in Table 310.15(B)(3)(a) as follows:
Size 1/0 AWG THW ampacity = 150 amperes before derating
150 amperes x 80% (adjustment factor) = 120 amperes

This definition is addressed in Article 100. Examples of continuous loads are lighting loads for commercial and industrial occupancies that are expected to be operated continuously for at least three (3) hours. Examples of noncontinuous loads are general-use receptacle outlets provided for commercial, industrial and residential occupancies and general-purpose lighting loads for residential occupancies. These types of loads are normally not in continuous use for 3 hours or more.

Section 230.71(A) mandates a building or structure may have not more than six (6) disconnecting means for the service conductors that supply the building or structure. One-set of service-entrance conductors, either overhead or underground, is permitted to supply two (2) to six (6) service disconnects instead of a single main disconnect.

Section 240.6(A) lists the standard ampere ratings of fuses and circuit breakers. Where the ampacity of a conductor, 800 amperes or less, does not correspond with a standard rating as listed in Section 240.6(A)(1), as per 240.4(B) you are permitted to go up to the next standard size if the conductors being protected are not part of a branch circuit supplying more than one receptacle.

Table 430.250 reflects the full-load current, in amperes, for three-phase ac induction-type motors running at usual speed with normal torque characteristics. This table is based on the most used induction motors in use. When applying this table, be sure and get on the correct horsepower and the corresponding voltage.

The purpose of this rule, Section 525.21(A), is so that the disconnecting means is located readily accessible to the operator, including when the ride is in operation. The operator can shut the ride down quickly when needed.

Annex C, Table C.1 is to be applied where the EMT, more than 24 inches in length, encloses conductors of the same size, with the same type of insulation. When referring to the tables in Annex C, be careful to select the correct raceway and conductor insulation and size.

To solve this problem refer to Section 215.3 which tells us the overcurrent protection is to be sized at not less than 125% of the continuous load to be served.

240 amperes x 125% = 300 amperes

This rule as indicated in Section 350.30(A) is in place to insure the LFMC is supported at intervals where it will not sag and perhaps pull apart.

Section 314.28(A)(1) applies to minimum dimensions of pull and junction boxes housing conductors of size 4 AWG or larger. The pull and junction boxes are to be sized in reference to the size of the raceways that enter and exit the pull and junction boxes.

Chapter 9, Informational Note Number 4 to the tables allows a permitted conduit or tubing fill of 60% of their cross-sectional area where the conduit or tubing is not more than 24 inches in length. This is permitted because short sections of the raceways readily permit easy pulling of the conductors and abrasion will not likely occur.

When determining the maximum number of conductors permitted in trade size 3/8 in. flexible metal conduit, refer to Table 348.22. The note at the bottom of the table allows an additional equipment grounding conductor of the same size.

Of the choices given, you should have selected nonmetallic conduit (PVC). Because of the chlorine present, Section 680.23(B)(2)(a) restricts metal conduit for this installation to be of brass or other approved corrosion- resistant material. Section 680.23(B)(2)(b) permits nonmetallic conduit to be used for this installation.

Section 680.10 allows wiring within 5 ft. of the inside walls of the pool under two conditions. One condition is, where the wiring is associated with the pool-associated equipment such as an underwater luminaire. Another condition is, where the space is limited such as restricted property lines.

Automotive-type batteries are not permitted for use as source of supply for emergency systems because they are not designed to hold a charge for extended lengths of time. See Section 700.12(A).

The nonheating leads of electric space heating cables are required to be at least 7 ft. in length in order to terminate the conductors to the power source. See Section 424.34.

Section 210.60(B) requires at least two (2) general-use receptacle outlets in guest rooms of hotels, motels and sleeping rooms of dorms to be readily accessible. Because of the furniture layout in these locations, many times the receptacle outlets are behind the furniture and rendered inaccessible. It is common practice for businessmen and students to use laptop computers and other plug-in devices in these rooms. The NEC requires that two receptacle outlets be available without requiring the movement of furniture to access those receptacles.

Section 700.8 requires emergency systems panelboards and switchboards to be equipped with a listed surge protective device (SPD) to limit transient voltages by diverting or limiting surge current. Surge protection is required for emergency systems since electronics monitor and control several aspects of the building involving such components as fire alarm systems, emergency and exit lighting, generator and transfer equipment, and automatic control relays. A spike or surge in current that goes unarrested can cause great damage to such components.

Heavy conductors and cables tend to stress the conductor insulation where the conductors and cables enter or exit the raceway. The intent of Section 300.4(G) is to reduce that stress and requires an insulated bushing or smooth rounded entries at raceway and terminations to reduce the risk of insulation failure at conductor stress points.

Fibers/flyings are hazardous not only because they are easily ignited, but also because flames spread through them quickly. Examples of Class III locations are textile mills, sawmills, plywood manufacturing plants, and other woodworking facilities. Refer to Section 500.5(D).

To solve this problem apply the single-phase current formula: I = P E

15 kVA x 1,000 = 15,000 = 62.50 amperes
240 volts 240

A motor used for duty-cycle service (short-time, intermittent, periodic, or varying) is not considered to be for continuous duty because the motor will not operate continuously due to the nature of the apparatus or machinery it drives. In compliance with Section 430.33, all other motors shall be considered to be for continuous duty.

As indicated in the exception to Section 430.84, a switch or circuit breaker is permitted to be used as both the controller and disconnecting means. If a switch or circuit breaker is used as a controller, they must be protected by short-circuit, branch-circuit, and ground-fault protective devices (fuses or circuit breakers), which ensure that all ungrounded conductors will be opened simultaneously.

In accordance with Section 220.14(I), for other than dwelling units, all 125-volt, single-phase, 15- or 20-ampere receptacle outlets shall be calculated at not less than 180 volt-amperes for each single or for each multiple receptacle on one yoke or strap.

Refer to Table 310.104(A) and notice that conductors with THHW insulation are rated at 75C when used in a wet location and have a rating of 90C when used in a dry location. Next, refer to Table 310.15(B)(16) and note conductors in the 90C column have a greater ampacity than those listed in the 75C column.

The intention of Section 250.112(M) is to prevent a shock hazard that could exist due to a potential difference between the pump, which is grounded to the electrical system ground, and the metal well casing. This grounding and bonding connection also provides a return path for ground-fault current.

Section 210.50(C) mandates the receptacle to be located within 6 ft. of the intended location of the appliance to eliminate the use of extension cords which may become frayed and brittle when used for an extended length of time.

When determining the allowable ampacity of single insulated conductors installed in free air refer to Table 310.15(B)(17). Note that size 8 AWG conductors with type FEPB insulation have a temperature rating of 90C and an allowable ampacity of 80 amperes.

The intent of Section 314.16(B)(4) is to prevent overcrowding of conductors and devices installed in device boxes. Devices such as switches, standard receptacles, AFCI receptacles and GFCI receptacles, mounted on a single strap, are to be counted as equal to two (2) conductors, based on the largest conductor connected to the device.

As per Section 430.6(A)(1), in general, when sizing the conductors, disconnecting means, and overcurrent protection for continuous-duty ac motors, the full-load current values of the motors given in Tables 430.247 through 430.250 shall be used instead of the actual current rating marked on the motor nameplate. Since the question referenced a 3-phase motor, the full-load current values shown on Table 430.250 should be used.

Section 404.2(A) requires all switching is done only in the ungrounded (hot) circuit conductor and not in the grounded (neutral) conductor when wiring three-way and four-way switches. As per 404.2(B),Ex, switches may only disconnect the grounded circuit where all circuit conductors, grounded and ungrounded are disconnected simultaneously.

When electrical conduit or tubing enclose conductors of the same size, with the same type of insulation, and the conduit or tubing is more than 24 inches in length, application of Annex C, Tables C.1 through C.12(A) is permitted to be used when determining the maximum number of conductors permitted in the conduit or tubing. For this question refer to Annex C, Table C.10(A). When referring to the tables in Annex C, be careful to select the correct raceway, conductor size and insulation.

Infrared commercial and industrial heating appliances are not unlike other commercial-type electric heating appliances where the heating elements, or lamps in this case, are to be subdivided. Each section carrying a number of infrared lampholders shall be considered an appliance and the overcurrent protection shall be rated at not over 50 amperes. Reference Section 422.11(C).

Class I locations are those locations where the handling or processing of volatile flammable liquids such as gasoline or flammable gases such as propane take place. Gas stations, gasoline plants and propane filling stations are three examples of this type of location. Refer to Section 500.5(B).

According to Section 300.6(D), in commercial or industrial facilities where walls are frequently washed, all metallic boxes, raceways, panelboards and fittings shall be mounted so that there is at least in. airspace between it and the wall to prevent corrosion.

The intent of Section 210.3 is to clarify that the ampere rating of a branch circuit is based on the size or rating of the overcurrent protective device and not on the wire size. For example, to limit voltage drop, where a branch circuit is wired with size 10 AWG copper conductors, with an allowable ampacity of 30 amperes, and is protected by a 20-ampere circuit breaker, the circuit is rated 20-amperes.

The reason for limiting the overcurrent protection and subdividing the heating elements of resistance-type electric space heating equipment is to minimize the amount of damaging energy released into the heating elements in the event of a short circuit, thereby reducing the risk of fire. Refer to Section 424.22(B).

In compliance with Section 645.5(B)(1) the power-supply cords of information technology equipment have a maximum limited length of 15 feet. Note, interconnecting cables of information technology equipment as addressed in Section 645.5(C) are not limited to 15 feet.

The purpose of Section 210.8(A)(9) is to provide a better level of safety for occupants of a dwelling unit. Many times bathtubs or shower stalls are not always located in an area that meets the Article 100 definition of a bathroom and receptacles located in such areas might not require GFCI protection. An example of such an area would be room adjoining a bedroom with a bathtub or shower stall as the only plumbing fixture in that particular room. Therefore, GFCI protection is required where receptacles are installed within 6 ft. of the outside edge of dwelling unit bathtubs or shower stalls.

Article 100 defines an intersystem bonding termination to be a device that provides a means for connecting bonding conductors for communications systems to the grounding electrode system. This termination device is intended to have a sufficient capacity to provide a convenient means to connect multiple communications systems such as telephone, satellite, and CATV systems to the grounding conductors to the service grounding electrode system. This is a safety measure to prevent occurrences of voltage between the communications system and the power system.

According to Section 300.5(D)(1) direct-buried conductors emerging from from underground are required to be protected from damage up to a height of 8 feet above grade. Use of Schedule 80 rigid PVC and rigid metal conduit are good examples of the type of protection required.

As specified in Section 250.122 equipment grounding conductors are to be sized based on the rating or setting of the overcurrent protective device protecting the circuit. Table 250.122 indicates where the overcurrent protective device has a rating of 50 amperes, the equipment grounding conductor is required to be a minimum size 10 AWG copper.

The provisions of Section 230.95 first appeared in the 1971 NEC due to the unusually high number of equipment burndowns reported on large capacity 480Y/277 volt solidly grounded services. Ground-fault protection of services does not protect the conductors on the supply side of the service disconnecting means, but it is designed to provide protection from line-to-ground faults that occur on the load side of the disconnecting means.

To determine the allowable ampacity of the size 500 kcmil THWN copper conductors first, find the ampacity of the conductors before derating, which is 380 amperes, as shown on Table 310.15(B)(16), then from Table 310.15(B)(2)(a) apply a temperature correction factor of .67 because of the elevated ambient temperature, next from Table 310.15(B)(3)(a) apply an adjustment factor of .7 due to the number of current-carrying conductors in the raceway. Follow the steps like this:

Size 500 KCMIL THWN copper ampacity before derating = 380 amperes
380 amperes x .67 (temp. correction) x .7 (adjustment factor) = 178.22 amperes

Section 348.20(A)(2) makes it clear that trade size 3/8 in. flexible metal conduit (FMC) is permitted to be used as the manufactured or field-installed raceway (not more than 6 ft. in length) to enclose tap conductors between an outlet box and a luminaire. Also, reference Section 410.117(C).

Because it is practically impossible to prevent the communication of gases and gas vapors in threaded conduit joints installed in Class I locations, as per Section 501.15(A)(1), a conduit seal shall be installed within 18 in. of an enclosure. Section 501.15(C)(3) mandates the thickness of sealing compound contained within the sealing fittings shall not be less than 5/8 in.

Section 210.8(A)(10) specifies dwelling unit laundry areas to provide GFCI protection for all 125-volt, single-phase, 15- or 20-ampere receptacles regardless of the presence of a sink or the distance from the sink. Laundry areas typically involve electrical appliances and the presence of water, which increases the risk of electrical shock hazards. This rule is in place as an effective means of reducing the potential for electrical shock hazards for residential occupants. Section 210.12(A) lists the areas of a dwelling unit where 120-volt branch-circuits supplying outlets and devices are required to have AFCI protection; laundry areas are included in this area. The purpose of an arc-fault circuit interrupter is to de-energize the branch circuit when an arc fault is detected; thus, reducing the potential of fire occurring.

The full-load running current values of three-phase, ac motors are shown in Table 430.250. When applying this table be careful to reference the correct horsepower and voltage.

As provided in Section 210.52(G), the branch-circuits supplying garage receptacles are permitted to supply only garage outlets. This is an effort to recognize the possibility of electric vehicle (EV) and plug-in hybrid vehicle (PHEV) charging stations being utilized. This rule assists in the ability of the garage receptacle outlets to have enough capacity to handle a load such as an EV charging station.

Section 200.6(D)(2) requires when different electrical systems are installed in the same raceway, one grounded conductor shall be white or gray in color and the other system grounded conductor shall have colored stripes (other than green) for the entire conductor insulation length. This requirement applies only where grounded conductors of different supply systems are installed in a common raceway or enclosure. Where grounded systems of different supply systems are installed in a common enclosure, identifying the grounded conductors associated with one system from the grounded conductors of another system helps to ensure proper system connections.

As per Section 376.56, splices and taps are permitted within a wireway, provided they are accessible. The splices and taps shall not fill the wireway to more than 75 percent at that point. Conductors in wireways can be accessed through hinged or removable covers.

The purpose of this rule found in Section 352.26 is to limit the number of bends in a conduit run to reduce pulling tension on the conductors and to help ensure easy insertion of the conductors.

As indicated in Section 250.52(A)(5)(a), a metallic pipe or conduit is permitted for use as a driven ground rod provided the pipe or conduit is not smaller than trade size in., galvanized or corrosion protected.

In accordance with Section 350.12(1), liquidtight flexible metal conduit is not intended for use where subject to physical damage.

The 3 ft. clearance rule required by Section 230.9(A) applies to open conductors, not to a raceway or to a cable assembly. The intent is to protect the conductors from physical damage and to protect persons from accidental contact with the conductors.

Section 110.14(C)(1)(a) requires that conductor terminations, as well as conductors, be rated for the operating temperature of the circuit. In other words, conductors must be sized to the lowest temperature rating of the wire, circuit breaker terminal, or device. In compliance with Section 110.14(C)(1)(a)(1), when terminating conductor sizes 14 AWG through 1 AWG on circuit breakers, unless the circuit breakers are marked and otherwise listed, the conductors have a temperature rating of 60C.

To ensure PVC conduit is securely supported and stable, Table 352.30 shows trade size 2 in. PVC conduit is to be supported at least every 5 feet.

The intent of Section 250.24(C) is to clarify if the utility service supplying the premises wiring system is grounded, the grounded conductor, whether or not is used to supply a load, must be run to the service equipment, be bonded to the equipment and be connected to a grounding electrode system.

The reason Section 392.10(B)(1)(a) requires the rung spacing of ladder type cable tray containing single conductor cables of sizes 1/0 AWG through 4/0 AWG to be no more than 9 in. is to ensure the cable tray can adequately support the cables.

As indicated in Table 314.16(A) the FS box is permitted to contain no more than six (6) size 12 AWG conductors.

Section 210.8(B)(2) was initiated because accident data related to electrical incidents in nondwelling kitchens revealed the presence of many hazards, including poorly maintained electrical appliances, damaged electrical cords, and wet floors. Therefore, all 15-and 20-ampere, 125 volt receptacles in nondwelling type kitchens are required to be GFCI protected.

Because of the diversity of the loads associated with dwelling units, Section 310.15(B)(7) allows an ampacity reduction of not less than 83% of the ampacity values of Table 310.15(B)(16) to be used to size the service-entrance conductors.

150 amperes x 83% = 124.5 amperes Size 1 AWG copper THHW Type SE cable with an ampacity of 130 amperes should be selected from Table 310.15(B)(16).

The requirement of Section 430.24(1)&(2) is based on the principle that the conductors supplying more than one motor should be sized to have an ampacity equal to 125 percent of the full-load current of the highest rated motor in the group, plus the full-load currents of all other motors and all other loads supplied by the conductors.

As per Section 250.122(A), the size of the equipment grounding conductors are based on the size of the overcurrent protective device and selected from Table 250.122

The main rules of Section 430.102(A) and (B) require that the disconnecting means be in sight of the controller. As per the exception to 430.102(B) the disconnecting means is permitted to be out of sight of the motor if it is capable of being locked in the open position.

As mandated by Section 440.32, branch-circuit conductors supplying a single motor-compressor are to have an ampacity of not less than 125% of the rated-load current as indicated on the nameplate.

35 amperes x 125% = 43.75 amperes

Size 8 AWG 75 C copper conductors with an ampacity of 50 amperes should be selected from Table 310.15(B)(16).

In compliance with Section 250.66, the size of the grounding electrode conductor at the service at each building or structure is based on the size of the largest ungrounded service-entrance conductor or equivalent area for parallel conductors. The size of the grounding electrode conductor shall not be less than given in Table 250.66. Apply Table 250.66 as shown:

Size 500 kcmil x 4 conductors = 2,000 kcmil total area

*NOTE: Aluminum service-entrance conductors over 1750 kcmil require a size 3/0 AWG copper grounding electrode conductor.

As required in Section 334.15(B), where exposed Type NM cable passes through a floor it is to be protected from physical damage by an approved means up to a height of 6 in. above the floor.

Section 647.1 requires when installing wiring for sensitive electronic equipment, the maximum voltage to ground is permitted to be no more than 60 volts.

Section 517.19(B)(1)&(2) specifies the number of receptacles and the type of circuits required for patient bed locations in critical care areas of health care facilities. Each patient bed location must be provided with at least fourteen receptacles that may be of the single, duplex, or quadplex type, provided they are listed hospital-grade type and are identified as such, typically with a green dot.

Where intermediate metal conduit is threaded in the field, a standard cutting die with a taper of 3/4 in. per foot shall be used. Refer to Section 342.28.

Section 424.44(G) requires the use of GFCI protection where heating cables are installed in concrete or poured masonry floors of bathrooms, kitchens and hydromassage bathtub locations. This requirement helps to reduce shock hazards to persons with bare feet in these areas. The GFCI protection is mandatory regardless of the type of floor covering over the concrete or poured masonry.

An acceptable marking method for the grounding pole on a grounding type receptacle is a green-colored hexagonal-headed or shaped terminal screw or nut, not readily removable. Refer to Section 406.10(B)(1).

Section 680.21(A)(5) allows pool-associated motors to employ cord-and-plug connections, provided the flexible cord does not exceed 3 feet in length.

Section 250.53(H) mandates plate grounding electrodes to be installed not less than 30 inches below the surface of the earth.

All fuses in circuits over 150 volts to ground shall be provided with a disconnecting means on their supply side so that each circuit containing fuses can be independently disconnected from their source of power. Refer to Section 240.40.

To determine the voltage-drop, first find the circular mil area of the conductors as shown in Chapter 9, Table 8. Then apply the single-phase voltage-drop formula as follows:

VD = 2KID VD = 2 x 12.9 x 80 amps x 200 ft. = 7.84 volts
CM 52,620 CM

The requirements for the location of conduit seals are to prevent an explosion from traveling through the conduit to another enclosure and to minimize the passage of gasses or vapors from hazardous locations to locations that are not considered hazardous. In Class I, Division I locations, where the conduit enters an enclosure that contains arcing devices, a sealing fitting is required to be installed within 18 in. of the enclosure. Refer to Section 501.15(A)(1).

In compliance with Section 110.3(B), listed or labeled equipment shall be installed and used in accordance with any instructions included in the listing or labeling.

Table. 514.3(B)(1) indicates, up to 18 in. above grade level, and extending a distance horizontally of 20 ft. from the outdoor motor fuel dispensing pumps, the area is considered a Class I, Division 2 hazardous location.

As described at Section 517.30(B), the three mandatory separate branches of the hospital essential electrical system are the life safety, critical and equipment branch. These three separate branches of the essential electrical system are to be capable of supplying a limited amount of lighting and power service that is considered essential for life safety and effective hospital operation during the time the normal electrical service is interrupted for any reason.

Section 725.179(H) specifies that Class 3 single conductors shall not be smaller than 18 AWG and shall be Type CL3.

In compliance with Section 200.6(B)(4), an insulated grounded conductor of size 4 AWG and larger is permitted to be identified by means of white marking at its terminations. This marking shall encircle the conductor or insulation. The most common method of marking neutral conductors is by the use of white colored tape.

The intent of Section 680.26(B) is to ensure all metals parts of a swimming pool, such as the structural reinforcing steel and metal ladders, as well as metal components surrounding the pool, such as fences, be bonded together by use of a size 8 AWG, or larger, bare, solid, copper conductor.

Section 310.15(B)(3)(c) indicates to apply the ambient temperature adjustment values shown in Table 310.15(B)(3)(c) where conductors or cables are installed in raceways exposed to direct sunlight on or at least within 36 in. above a rooftop. The conductors in outdoor conduits installed on or near the surface of the roof are subject to a significant increase in temperature when the roof is exposed to direct sunlight. The closer the conduit is to the roof, the greater the ambient temperature adjustment.

Operation of a motor in excess of its normal full-load rating for a prolonged period of time causes damage or overheating that may cause a fire. Motors are required to be protected from overloads. Those motors with a temperature rise of more than 40C indicated on the nameplate are incapable of withstanding an overload for an extended period of time. Therefore, the rating or setting of the overload device shall be not more than 115% the full-load current rating as indicated on the motor nameplate. Refer to Section 430.32(A)(1).

As per Table. 210.21(B)(3) and Table 210.24, where a branch circuit is protected by a 15-ampere rated circuit breaker and size 14 AWG conductors are used, the receptacles must be rated 15-amperes.

Section 250.64(C)(1) prohibits the splicing of a grounding electrode conductor by use of a split-bolt connector, but permits a more permanent method of connection such as by exothermic welding or by irreversible compression-type connectors.

To determine how many conductors may be added to a junction box, first find the volume, in cubic inches, of the existing conductors in the box by applying the values, in cubic inches, as shown on Table 314.16(B). Size 12 AWG = 2.25 cu. in. x 6 (existing wire in box) = 13.5 cu. in. Next, subtract the cu. in. volume of the existing wires in the box from the allowable fill of the box to find the remaining space available.

27.0 cu. in. (allowable fill of box)
-13.5 cu. in. (existing wire in box)
13.5 cu. in. (remaining space available)

Then, divide the remaining space available by the cu. in. volume of the size10 AWG conductors to be added.

13.5 cu. in. (remaining space) = 5.4 = 5 size 10 AWG wires may be added
2.5 cu. in. (10 AWG)

As per Section 550.10(G) the trade size 1 1/4 in. conduit is of adequate size to enclose and protect the conductors.

You should have selected all of the above because Section 511.7(A)(1) permits all of the wiring methods listed to be used for fixed wiring in an area above Class I locations in a commercial garage.

Section 225.19(B) requires a clearance of not less than 3 ft. from outside open conductors and signs, chimneys, and TV antennas to prevent a shock hazard and a ground-fault.

As per Section 422.13, for the purposes of sizing branch circuits for a fixed storage-type water heater, the water heater shall be considered a continuous load. In compliance with Section 422.10(A), branch circuit conductors supplying an appliance considered a continuous load are required to have an ampacity of not less than 125% of the marked rating of the appliance.

The reason for subdividing the overcurrent protection on household-type appliances with surface heating elements is to minimize the amount of damaging energy released into the heating elements during a short circuit, hereby reducing the risk of fire. Refer to Section 422.11(B).

Section 250.53(G) requires that all rod and pipe grounding electrodes have at least 8 ft. in length in contact with the soil. Where rock bottom is encountered, the electrodes are permitted to be buried in a 2 ft. (30 in.) deep trench.

Section 310.15(B)(3)(a)(2) clarifies that adjustment factors for more than three (3) current-carrying conductors in raceways shall not apply where the raceway is not more than 24 inches in length. Where more than 3 current-carrying conductors are installed in short lengths of conduit or tubing, the heating effect caused from the additional conductors is insignificant. Therefore, the allowable ampacity of the conductors is not greatly reduced.