Fundamental Code Calculations Practice Test

These questions are part of the practice quiz. Start practicing

• What type of box is installed in a run of conduit for making splices without supplying utilization equipment directly from the box?
• What is the required marking on conduit bodies that contain splices?
• What is a conduit body?
• What is the ampacity of four 14-2 NM cables routed through wood framing filled with caulk?
• What is the maximum load for a conductor not to exceed the table value multiplied by what factor?
• What minimum size aluminum wire is needed for a 440-volt, 3-phase branch circuit supplying a 60-ampere load at 325 feet?
• According to the NEC, when do rules apply regarding conductors that are mixed in size and insulation?
• What is the maximum length of a single-phase, 120-volt branch circuit supplying a 10-ampere load with 14 AWG conductors without exceeding a voltage drop of 3.6 volts?
• What ampacity is needed for twelve 12 AWG conductors in a 3-phase wye-connected system?
• Which formula determines the maximum fuse size for a transformer with a 31.25-ampere full load current rating using primary only protection?
• In the context of conductor sizes, which term refers to the system used to categorize wire gauge?
• A load where the maximum current is expected to continue for 3 hours or more would be defined as?
• What is the minimum length for a pull box when using a four-inch RMC for a straight pull with conductors sized 4 AWG or larger?
• What is a common reason for derating conductors in conduit?
• What size Flexible Metal Conduit is needed for three 14/2 NM cables if each cable has a width of 372 mils and height of 170 mils?
• What is the maximum percentage of cross-sectional area allowed in a nonmetallic wireway?
• What size Schedule 40 Rigid PVC is required for two 10/2 NM cables with specified dimensions?
• What is a unit of an electrical system that carries or controls electric energy as its principal function?
• Which section of the Code would most likely define "Conductor Material Type"?
• For a 208Y/120-volt, 110-ampere feeder supplying a single dwelling unit, what is the minimum size THWN-2 grounded feeder conductor required?
• What conductor size is necessary for a 120-volt circuit supplying a load of 30 amperes considering Code limits?
• What is the maximum number of 14 AWG THWN copper conductors that may be added without exceeding the fill limit in a raceway with four 12 AWG conductors?
• What is the primary purpose of using rigid metal conduit?
• What happens if a conductor is operated above its ampacity rating?
• To what maximum length can a conduit nipple be filled to 60% of its total cross-sectional area?
• For a 4 in. × 11/2 in. square box, how many 6 AWG TW conductors are allowed according to Article 314?
• How is ampacity defined?
• What is the ampacity of two 8 AWG THWN-2 copper conductors installed in rigid metal conduit at an ambient temperature of 86°F?
• According to NEC, which section requires that electrical equipment must be used according to the manufacturer's instructions?
• What size overcurrent protective device is typically required for a noncontinuous load?
• What is the minimum size THW branch circuit conductors required for a 240-volt, 4-kilowatt electric baseboard heater?
• What is the ampacity of each 12 AWG conductors in ambient temperature of 32°C with twelve 12 AWG THHN conductors?
• How many conductor allowances are present in the box with two 12 AWG conductors entering and leaving?
• Does the NEC intend to define terms which have general usage elsewhere?
• Which size Electrical Metallic Tubing is appropriate for containing a circular 6/3 NM Cable with a diameter of 0.672 inches?
• Which item does not typically require special considerations for installation when handling electrical conductors?
• What is the ampacity of each 12 AWG conductor in a 4-conductor metal-clad cable supplying dedicated 20-ampere computer circuits in a temperature of 32°C?
• According to NEC 110.14(C)(1)(a)(2), what column of Table 310.16 is used for the ampacity of a 75°C conductor with devices marked 60°C?
• A load that is expected to last for 3 hours or more would fall under which classification?
• What is the ampacity of a 4/0 AWG THW conductor for use in a branch circuit?
• How much greater is the resistance in ohms per 1,000 feet (Ω/kFT) of an uncoated 10 AWG stranded copper conductor than that of a 10 AWG solid copper conductor?
• What is the ampacity of three 8 AWG THHN copper conductors in a nonmetallic wireway at 35°C?
• What must be considered when calculating box fill for conductors?
• What is the minimum size THW branch-circuit conductor permitted for protection when the overcurrent protective device is rated at 50 A?
• Which section of the NEC places limits on maximum circuit load based on the size of the conductors?
• What wire gauge should be used for the minimum size service conductors for a 200A-rated service in copper?
• What impact does ambient temperature have on the ampacity of conductors?
• A 4-square box with two receptacles installed adds how many additional conductors to the fill allowance?
• Which of the following conductors is classified as a current-carrying conductor according to 310.15(C)(1)?
• What is the minimum size metal device box recommended for an installation with isolated equipment grounding?
• What is the minimum size THWN-2 ungrounded feeder conductor required to supply a dwelling unit with a load at 110°F?
• Throughout the NEC, conductor sizes are expressed in which two units?
• What is the minimum size copper THW grounded service entrance conductor required for a dwelling with a 75-amp load?
• Which two parts of Article 310 contain tables used to calculate conductor ampacity?
• Which of the following loads is generally considered a continuous load?
• Which formula corresponds to the requirement for the ampacity of conductors that connect a capacitor to motor circuit conductors?
• A 120-volt circuit supplies 38 amperes of continuous load. What is the minimum standard size fuse required for overcurrent protection of the circuit?
• What is one main purpose of determining the maximum percentage of fill in conduit installations?
• What size copper conductors are needed to supply a 3-phase, 208-volt, 200-ampere load at a distance of 250 feet with a maximum of 3% voltage drop?
• What type of heat is retained due to the surrounding media's inability to dissipate heat?
• What is the maximum standard size overcurrent protective device allowed for THW conductors rated at 75°C?
• What is the minimum length and width of a handhole enclosure with a three-inch non-metallic conduit entering and exiting?
• Which type of protection is required for circuits supplied from both industrial and commercial locations?
• What is the maximum percentage of fill for 10 feet of Schedule 80 PVC conduit for a 3/0 THWN-2 grounding electrode conductor?
• A box with four internal cable clamps adds how many additional conductors to the fill allowance?
• What is a part of a wiring system that is intended primarily to perform a mechanical function?
• What voltage drop should not be exceeded for a branch circuit supplying a 10 ampere load?
• For a properly designed electrical installation, what should be checked in terms of conductor size and distance?
• How much larger is the diameter of an 8 AWG stranded conductor than that of an 8 AWG solid conductor?
• Under which of the following conditions do the ampacities specified in Table 310.16 apply?
• Which of the following is NOT counted towards box fill?
• A circuit supplying a continuous load must have a circuit breaker rated for what minimum amperage if it has a load of five kilowatts?
• Can both aluminum and copper conductors be supplied with compact wire stranding?
• What is the resistance of 175 feet of 14 AWG stranded uncoated copper conductor?
• What is the ampacity of each 3/0 AWG conductor in a 4-conductor, metal-clad cable supplying discharge lighting?
• What is the ampacity of each current-carrying conductor when nine 8 AWG THHN copper conductors are supplied to three 3-phase motors in a rigid metal conduit?
• What is the minimum standard size overcurrent protective device required for a 480-volt, 3-phase feeder with 85 amperes continuous and 50 amperes noncontinuous load?
• A device box is commonly referred to in the field as what type of box?
• What is the ampacity of two 4 AWG XHHW-2 aluminum conductors in rigid metal conduit at an ambient temperature of 50°C?
• According to Table 314.16(A), dimensions for standard size are specified for which of the following?
• What is the required insulation rating for the 12 AWG copper conductors in the office building circuit?
• What is the maximum number of 3/0 AWG XHHW aluminum conductors permitted through a 6-inch by 6-inch by 24-inch nonmetallic auxiliary gutter?
• What is the minimum size IMC required for the installation of three 4/0 AWG THW copper conductors, three 2 AWG THW copper conductors, and three 1 AWG THW copper conductors in the same conduit?
• What is the minimum standard size overcurrent protective device required for a 120/208-volt, 3-phase feeder supplying a continuous load of 37.5 kVA?
• What is the voltage drop on a single-phase, 208-volt branch circuit supplying a 130-ampere load at a distance of 185 feet with 2/0 AWG THWN aluminum conductors?
• Which of the following is NOT a factor for determining conductor size?
• What is the ampacity of one of twenty-four 12 AWG THWN copper motor circuit conductors?
• What is the minimum standard size square metal box required for two 12 AWG, two 14 AWG, and four 10 AWG THHN copper conductors?
• In electrical terminology, what does OCPD stand for?
• What is the minimum length for a handhole enclosure when installing two four-inch non-metallic conduits on opposite sides, given that the conductors are sized 4 AWG or larger and are not spliced?
• What type of conduit is typically used for outdoor or underground installations?
• What is the maximum ampacity rating of three 3/0 AWG THHN conductors in a 90°C ambient temperature?
• What is the minimum length and width of a pull box having an angle pull with one three-inch conduit coming in and one three-inch conduit leaving on adjacent sides?
• What characteristic of conductors is directly related to the conductor's ampacity?
• Which installation allows the use of Table 310.12(A)?
• What conductor size is recommended for aluminum conductors in a residential service-entrance at 120 amperes?
• What is the minimum size EMT required for the installation of four 12 AWG and four 10 AWG THHN copper conductors?
• When calculating voltage drop, which factor is crucial for determining the appropriate wire size?
• For a 230-volt supply, what is the typical voltage drop acceptable for a 125-ampere load?
• When calculating ampacity, which factor is not typically considered?
• What is the minimum standard size inverse-time circuit breaker for a 480-volt, 3-phase circuit with a 50-kilowatt continuous load?
• What is the minimum box volume requirement for a 120/240-volt, 50-ampere range receptacle supplied by an 8-3 NM-B cable?
• What is the voltage drop in volts for a branch circuit supplying a 215-ampere load at 118 feet?
• What is the ampacity of a single 8 AWG THWN-2 copper conductor installed in free air at an ambient temperature of 50°C?
• What is the minimum size aluminum THW service-entrance conductors required for a load of 120 amperes on a 120/240-volt system?
• What is the maximum fuse size for a transformer with a six-ampere full load current rating using primary only protection?
• What is the maximum number of 12 AWG THHN copper conductors permitted in a standard 3/4-inch LB conduit body?
• What is the maximum number of 10 AWG THWN conductors permitted through a cross-section of 4-inch-wide by 4-inch-deep by 30-foot-long metal wireway?
• What is the ampacity of a 12 AWG THWN-2 copper conductor when connected to a circuit breaker with a termination temperature of 60°C/75°C?
• In a voltage calculation for conductors, the ampacity needs to be greater than what formula?
• What minimum size ungrounded THHN conductors are required for a 120/208-volt, 3-phase feeder supplying continuous load of 37.5 kVA?
• What is the maximum allowable sum of cross-sectional areas for conductors in a nonmetallic auxiliary gutter?
• What is the resistance of 500 feet of uncoated copper with a cross-sectional area of 250,000 circular mils?
• What is the ampacity adjustment factor for three conductors in a conduit?
• What is the ampacity of each 12 AWG conductor when installed in a one-inch EMT with twelve conductors at an ambient temperature of 32°C?
• When comparing a 10 AWG uncoated copper conductor to a 10 AWG coated copper conductor, which statement is NOT true?
• What is the voltage drop on a 240-volt single-phase branch circuit supplying a 100-ampere load at 105 feet using 1 AWG THWN aluminum conductors?
• For a 120-volt, 15-ampere circuit, which conductor size is typically used?
• In what situation does Table 310.17 apply?
• What does TWH stand for in the context of electrical conductors?
• What size conductor should be used for a 50 A overcurrent protective device to ensure compliance?
• What is the ampacity of an 8-3 (plus ground) aluminum SE cable supplying a range receptacle?
• What is the maximum percentage fill of a one-inch IMC nipple 24 inches in length?
• What is the minimum size THWN-2 grounded feeder conductor required for a dwelling unit with a neutral load of 85 amperes?
• How do you calculate the voltage drop for a specific load on a branch circuit?
• What is the minimum size allowable for a conductor in a circuit with a continuous load at 30 amperes?
• What is the minimum length and width of a handhole enclosure for an angle pull with specific conduit entries?
• What factors can affect the ampacity of a conductor?
• What is the minimum box volume required for two 12 AWG conductors and two 14 AWG conductors in a splice?
• Which of the following is NOT part of the definition of ampacity?
• Which factor contributes to the selection of conduit size for a specific number of conductors?
• What term describes the stranding of a conductor that has virtually eliminated voids between the strands?
• What is the voltage drop on a 3-phase, 480-volt feeder supplying a 400-amp load at a distance of 95 feet with 500 kcmil THWN copper conductors?
• What is the typical application for a pull box in a conduit system?
• What is the resistance of 300 feet of 10 AWG solid aluminum conductor?
• Definitions for terms found in a single article will have the article number in parentheses following the definition. True or False?
• What is the ampacity rating of the cable supplying a dwelling unit range receptacle with a 60/75°C breaker?
• What is the ampacity of three 3/0 AWG THHN copper conductors installed in rigid nonmetallic conduit with a 90°C rating?
• What is the ampacity of three 12-2 conductor metallic cables, Type MC, grouped together?
• What is the maximum number of 10 AWG THW-2 conductors that can be added to a trade size 1 EMT raceway containing eight 12 AWG RHH conductors?
• What is the ampacity of a 4/0 AWG THHN aluminum conductor connected to a 200-ampere rated circuit breaker?
• What is the maximum number of 12 AWG THHN conductors permitted in a 4 11/16 in. × 11/2 in. square box?
• What is the maximum voltage drop permissible for a 440-volt circuit at 60 amperes?
• What is the ampacity of three 12 AWG THHN and three 14 AWG TW copper current-carrying conductors in a rigid metal conduit at an ambient temperature of 30°C?
• What does the concept of "weakest link" imply in electrical circuits?
• What minimum size copper wire is needed for a 230-volt branch circuit with a 65-ampere load at a distance of 250 feet?
• What is the minimum box volume needed for the installation of four 14 AWG THHN conductors and four 10 AWG THW conductors?
• What is the maximum current for a single-phase, 230-volt branch circuit supplying a load at a distance of 140 feet with 4 AWG copper conductors and holding the voltage drop to 4.6 volts?
• What is the minimum size metal device box suitable for two 12 AWG conductors passing through and two connected to a switch in a switch box?
• What minimum size copper wire is needed for a 120-volt single-phase branch circuit supplying a 30-ampere load at a distance of 205 feet to limit the voltage drop within the recommended Code limit?
• What is the voltage drop on a 3-phase, 480-volt branch circuit supplying a 120-ampere load at a distance of 65 feet?
• What is the ampacity of each of eighteen 10 AWG THHN copper current-carrying conductors in a metal wireway?
• What is the minimum size EMT required for the installation of eight 12 AWG THW copper current-carrying conductors and one 12 AWG THW copper equipment grounding conductor?
• In a multiwire branch circuit, how many conductors are needed for proper operation?
• What kind of box is designed for making electrical splices in conduit runs?
• The resistance of a conductor will change according to what factor?
• What is the total count of conductors required to determine the total box volume for a splicing box with two 12 AWG conductors in and out and a grounding conductor?
• What term describes heat generated by current flowing through adjacent load-carrying conductors?
• What is the smallest standard size metal box required for four 12 AWG RHH conductors?
• What is the minimum size ungrounded THWN conductors required for a 480-volt, 3-phase feeder with a continuous load of 85 amperes?
• What is the maximum number of 2/0 AWG THW aluminum compact conductors permitted in a 2 1/2-inch PVC conduit, Schedule 80?
• Which of the following formulas deals with the calculation for continuous load and non-continuous load?
• What is the minimum box volume required for a lighting outlet box with two 12 AWG and two sets of spliced 14 AWG conductors?
• What is the minimum length for a pull box when a run of three-inch RMC is installed for a straight pull?
• Does Chapter 9, Table 1 of the National Electrical Code apply when conductor sizes and/or insulations are mixed?
• What is the recommended voltage drop limit for branch circuits according to the Code?
• What is the ampacity of a single 8 AWG THWN-2 copper conductor installed in free air at 30°C?
• Which of the following is the required temperature rating for the ampacity of a conductor?
• In which situation would you typically calculate voltage drop?
• What is the recommended practice before selecting the size of an overcurrent device?
• Which of the following statements is true regarding the sizing of circuit conductors and the overcurrent device?
• What is the ampacity of an 8 AWG THHN cable with 23 other conductors at an ambient temperature of 30°C?
• A box with four external cable clamps contributes how many additional conductors to the fill allowance?
• In wiring installations, what would result from mixing different temperature-rated insulation?
• What is the ampacity of three 1/0 AWG THW aluminum conductors installed in rigid metal conduit at an ambient temperature of 104°F?
• In a 4-inch by 4-inch metal wireway, how many 1 AWG THHN conductors can be added if there are twelve 8 AWG THW conductors already present?
• In a scenario with two 2-conductor, 14 AWG copper wires and one 2-conductor, 10 AWG copper wire in EMT, what is the ampacity of one 10 AWG copper conductor in 101°F ambient temperature?
• Which table in Chapter 9 of the NEC is used to determine the approximate area of a compact aluminum conductor with XHHW insulation?
• What methodology should be used to calculate the ampacity of wires in a metal wireway?
• What is the maximum number of 6 AWG THW copper conductors permitted in a one-inch EMT?
• What minimum size aluminum THWN grounded service-entrance conductor is required for a dwelling unit with a neutral load of 99 amperes?
• For which of the following would you apply circuit protection standards?
• Which type of conduit is mentioned for installation of conductors in the given specifications?
• How many conductors are considered when calculating the box volume for a device where splicing occurs?
• What is the minimum size EMT needed for a combination of six 1 AWG, eight 2 AWG, and four 1/0 AWG THW conductors?
• What is the voltage drop on a single-phase, 208-volt branch circuit supplying a 54-ampere load at a distance of 98 feet using 6 AWG RHW uncoated copper conductors?
• What is the minimum size THHN feeder circuit conductors required for a circuit with 80 amperes of continuous load?
• How is the ampacity affected for conductors located in a conduit alongside other conductors?
• Do the following items count towards box fill: Bushings, Hickeys, and Single pole switch?
• What is the minimum length for a pull box when two runs of three-inch RMC are installed adjacent to each other?
• What is the voltage drop on a single-phase, 240-volt branch circuit supplying a 48-ampere load at a distance of 88 feet using 4 AWG RHW aluminum conductors?
• Which is true regarding the length of installations for specific conductor sizes?
• What is the minimum length for a handhole enclosure when a run of three and one half-inch PVC is installed for a straight pull through the enclosure?
• What is the purpose of a pull box installed in a run of conduit?
• According to the NEC, the ampacity of capacitor circuit conductors should not be less than what percentage of the rated current of the capacitor?
• How long of a conduit nipple is allowed to be filled to 60% capacity?
• Which of the following loads would typically be considered a continuous load?
• What is the maximum length for a single-phase, 110-volt branch circuit with a 40-ampere load using 6 AWG aluminum conductors?
• What is the maximum number of 4/0 AWG THHN copper conductors permitted to be installed in a two-inch IMC?
• Which Code section deals with voltages used for calculating loads?
• What is the maximum number of 10 AWG THWN-2 conductors allowed in a 1-inch Electrical Nonmetallic Tubing?
• What principle is applied to determine the temperature rating of a circuit with mixed component temperature limitations?
• Which of the following does not specifically change the DC resistance of a particular conductor?
• For the listed voltages, which ones are NOT accounted for by the Code's calculations?
• What is the maximum number of 12 AWG THWN-2 conductors permitted in a trade size 1/2 RMC conduit, 18 inches in length?
• Which of the following installations does NOT require the application of Table 310.15(C)(1)?
• When a load is applied to the system, how does the ampacity of conductors change with respect to temperature adjustments?
• What is the minimum box volume requirement for two 12-2 NM-B cables and one 14-3 NM-B cable?
• Are aluminum conductors available with compact wire stranding?
• What is the relationship between conductor size and ampacity according to standard code?
• What is the voltage drop on a 3-phase, 230-volt branch circuit supplying a 125-ampere load at a distance of 175 feet with 4/0 AWG THWN copper uncoated conductors?
• What size Electrical Metallic Tubing is required for a 12/3 NM Cable with a width of 524 mils and height of 190 mils?
• Which of the following is NOT a valid formula according to the NEC?
• For residential wiring, the maximum number of conductors allowed in a box is guided by which standard?
• What size copper branch-circuit conductors are required for a 38-ampere, 3-phase load to avoid exceeding a 5% voltage drop at a distance of 110 feet?
• What is the ampacity of a 10 AWG THWN copper conductor when terminated to a circuit breaker with a maximum temperature of 60°C?
• Which of the following voltages are nominal system voltages specified for use in calculations by the Code?
• What is the resistance of 200 feet of 8 AWG coated solid copper conductor?
• What is the minimum depth of a handhole enclosure when installing a four-inch non-metallic conduit containing four 350kcmil THWN conductors?
• What is the resistance in ohms per 1,000 feet of a typical 10 AWG solid copper conductor?
• For a 100A-rated service, what is the minimum size THW service conductor using aluminum?
• What is the ampacity of a 14 AWG THW copper conductor connected to a motor marked with design letter B?