Electrician Practice Test

Part III of Article 310- Conductors for General Wiring, covers the general installation requirements for conductors rated up to and including 2000 volts. Section 310.14(B) tells the reader the ampacity of each conductor within a raceway needs to be corrected for ambient temperatures other than 30°C (86°F). Using the values shown in Table 310.15(B)(1), multiply the ampacities of the conductors specified in the ampacity tables by the appropriate correction factor shown in Table 310.15(B)(1) to correct the ampacities of the conductors. Also, Section 310.14(C) tell us the ampacity of each conductor is to be adjusted as shown in Table 310.15(C)(1) where the number of current-carrying conductors within a raceway or cable exceeds three. Again, multiply the conductor ampacities as shown in the ampacity tables by the percentage values given in Table 310.15(C)(1).

Part VI of Article 250 explains the wiring methods and installation requirements for equipment grounding and equipment grounding conductors. Section 250.118 lists the approved types of equipment grounding conductors. 250.122(5)d. specifies where flexible metal conduit (FMC) is longer than 6 ft. it is not considered an effective ground-fault current path.

Article 210 provides the general requirements for branch circuits. Section 210.8(A)(2) requires all 125-volt through 250-volt, single-phase receptacles installed in residential garages to be provided with ground-fault protection for personnel. There are no exceptions to this rule, the receptacles must be provided with GFCI protection for the user of appliances or other equipment regardless of where the receptacle is located in the garage.

The uses and ampacity ratings of conductors for general wiring are found in Article 310. Section 310.3 specifies the minimum size of conductors for general wiring shall be 14 AWG copper or 12 AWG aluminum except as permitted elsewhere in the Code.

Article 406 covers the rating and installation of receptacles. Section 406.9(B)(1) addresses the installation of receptacles of 15- and 20-amperes placed in a wet location and specifies where the plug-and-cord connection to receptacles is in a wet location, the enclosure is required to be weatherproof regardless of whether or not the plug is inserted.

Section 310.12 of Article 310, Conductors for General Wiring, permits the values given in Table 310.12 for use when sizing service and feeder conductors under this condition. The table indicates size 4/0 AWG aluminum conductors are the smallest size permitted for a 200-ampere rated service if no adjustment or correction factors are applied. Note, the service-entrance conductors for dwellings, under this condition, is reduced in size in relation service-entrance conductors for commercial and industrial occupancies due to the dwelling unit's diversified load.

Article 314 governs the installation and use of all outlet and device boxes. Table 314.16(A) shows six (6) size 12 AWG conductors are permitted in the FS box however, Section 314.16(B)(4) tell us the number of conductors allowed in the box shall be reduced by two (2) due to the receptacle contained in the FS box. Therefore, the box is permitted to have only four (4) size 12 AWG conductors.

Part III of Article 210 provides the general requirements for the required 125-volt, single-phase 15- and 20-ampere receptacle outlets in a dwelling unit. Section 210.52(C)(2)(b) specifies at least one receptacle outlet shall be located within 2 feet of the outer end of a peninsular countertop or work surface. Additional required receptacle outlets are permitted to be located as determined by the installer, home owner, or builder. This rule eliminates the need for extension cords.

Section 210.12 of Article 210, Branch Circuits, explains the rules for AFCI protection of 120-volt, single-phase, 15- and 20-ampere branch circuits supplying outlets or devices in a dwelling unit. 210.12(A)(4)b. calls for the conductors to have length restrictions to the first outlet from the overcurrent device, based on the size of the conductors; 50 feet for 14 AWG and 70 feet for 12 AWG conductors. This rule is in place to restrict voltage-drop and prevent nuisance tripping of the overcurrent protection device.

The rules for service equipment and service conductors and their installation requirements are found in Article 230. Section 230.85 tells the reader the required emergency disconnect provided for one- and two-family dwellings is to be installed in a readily accessible outdoor location. This mandate was established because of the need for first responders and utility personnel to have a way to safely remove power from the house in an emergency.

Part VI of Article 250 covers the wiring methods and installation requirements for equipment grounding and equipment grounding conductors. Section 250.118 lists the approved types of equipment grounding conductors and liquid-tight flexible metal conduit (LFMC) is included in the list. However, 250.122(6)d. tells the reader where the flex is longer than 6 feet it is not considered an effective type of equipment grounding conductor and a wire-type equipment grounding conductor needs to be installed.

Article 430 covers motors, motor conductors, motor protection, motor controllers, motor control circuits, and motor control centers. Section 430.6(A)(1) explains for a motor of this type, Table 430.250 that shows the full-load current (FLC) of motors, shall be used to determine the ampacity of conductors or ampere ratings of switches, branch-circuit short-circuit and ground-fault protection, instead of the actual ampere rating marked on the motor nameplate. Section 430.6(A)(2) indicates the ampere rating (FLA) provided on the motor nameplate is used to size the overload protective devices that protects the motor, motor controller, and motor branch-circuit conductors. Overloads are not a fault condition, overloads happen when there is excessive current in the circuit. An overload is where the current is more than the equipment ampere rating and the overload may result in overheating and damaging equipment. Overload protection does not protect against short-circuits or ground-fault currents.

Part II of Article 250 addresses the general requirements for system grounding and bonding of alternating-current systems to be grounded. Section 250.24(B) requires an unspliced main bonding jumper to connect the equipment grounding conductor and the service disconnect enclosure to the neutral (grounded conductor) within the enclosure. The size of the main bonding jumper is determined in accordance with Table 250.102(C)(1).

The provisions of Article 680 apply to the installation and wiring methods of storable or permanently installed swimming pools, hot tubs and spas, and to their metallic auxiliary equipment, such as pumps and similar equipment. Section 680.41 in Part II of Article 680 was initiated because, a local disconnecting device, not less than 5 ft. away from the hot tub, that is capable of being used in an emergency is needed for hot tubs and spas to allow rapid disconnection if someone becomes entrapped by the water recirculation system intake.

Article 440 applies to air-conditioning and refrigeration equipment and to branch circuits and controllers for the equipment. Section 440.14 prohibits the disconnecting means to be located on panels that are designed to allow access to the equipment or to obscure the equipment nameplate.

The rules regarding the use and installation of rigid metal conduit (RMC) are found in Article 344. As per Section 344.30(A), as a general rule, RMC is required to be supported least every 10 feet and within 3 feet of each outlet box, junction box, panelboard or any similar cabinet unless otherwise permitted by 334.30(B). Section 334.30(B)(3) permits the exposed vertical risers of RMC from industrial machinery or fixed equipment to be supported at intervals of 20 feet when the conduit has threaded couplings, fastened at the top and bottom of the riser, and no other means of immediate support is readily available.

Article 445 contains installation and other requirements for generators. Section 445.13 specifies, the ampacity of the conductors from the generator terminals to the first overcurrent protection shall not be less than 115 percent of the nameplate current rating of the generator. Apply the single-phase current formula to solve this problem. I = P ÷ E

  I =  22 kw x 1000  = 22,000  = 92 amperes x 1.15 = 106 amperes
          240 volts            240
 

Article 605 covers electrical equipment, wiring methods and conductors installed in office furnishings. Section 605.9(D) does not permit an individual office furnishing to contain multiwire circuits. Although multiwire branch circuits are not permitted in cord-connected office furnishings, they may be supplied by one phase of a multiwire branch circuit.

Part VI of Article 250 explains the wiring methods an installation requirements for equipment grounding and equipment grounding conductors. Section 250.118 lists the approved types of equipment grounding conductors. 250.118(5)c. specifies where flexible metal conduit (FMC) exceeds trade size 1¼ in. it is not approved for use as an equipment grounding conductor and an additional wire-type equipment grounding conductor needs to be installed in the flex.

Part II of Article 680 applies to the rules governing the installation and wiring methods of permanently installed swimming pools. Section 680.21(A) mandates when wiring a swimming pool pump motor, the raceway containing the supply conductors shall also contain an insulated copper equipment grounding conductor not smaller than 12 AWG in order to have an effective ground-fault path.