CSLB General Building (B) — All Questions

A single-family dwelling has 2,000 sq ft of habitable floor area. Using the standard calculation method at 3 VA per sq ft, what is the general lighting and general-use receptacle load before any demand factors?

• a.6,000 VA✓
• b.4,000 VA
• c.8,000 VA
• d.3,000 VA

General lighting is figured at 3 VA per sq ft: 2,000 sq ft x 3 VA = 6,000 VA. This value is calculated before applying the general-lighting demand factors.

In the standard dwelling calculation, what is the minimum load to include for two required small-appliance branch circuits plus one laundry branch circuit, before any demand factor?

• a.3,000 VA
• b.4,500 VA✓
• c.6,000 VA
• d.1,500 VA

Each small-appliance and laundry circuit is figured at 1,500 VA. Two small-appliance circuits (2 x 1,500 = 3,000) plus one laundry circuit (1,500) equals 4,500 VA.

A dwelling has 7,200 VA general lighting, 3,000 VA small-appliance, and 1,500 VA laundry. Applying the standard demand factor (first 3,000 VA at 100%, remainder at 35%), what is the net general lighting load?

• a.11,700 VA
• b.7,200 VA
• c.6,045 VA✓
• d.4,095 VA

Sum = 7,200 + 3,000 + 1,500 = 11,700 VA. First 3,000 at 100% = 3,000; remaining 8,700 at 35% = 3,045. Net = 3,000 + 3,045 = 6,045 VA.

Using the demand table for household electric ranges, what is the demand load for one 12-kW electric range in a dwelling (Column C, one appliance)?

• a.12,000 VA
• b.9,600 VA
• c.6,000 VA
• d.8,000 VA✓

For a single household range not over 12 kW, the Column C demand is 8 kW = 8,000 VA. The 12-kW nameplate is reduced to an 8-kW calculated demand for one range.

What is the demand load for two 12-kW household electric ranges served from one feeder (range demand table, Column C, two appliances)?

• a.11,000 VA✓
• b.16,000 VA
• c.12,000 VA
• d.19,200 VA

Two ranges not over 12 kW have a Column C demand of 11 kW = 11,000 VA. This is less than the 24,000 VA connected total because of diversity.

A single household range is rated 16 kW. Using the 5% increase per kW over 12 kW rule on the 8-kW base, what is the demand load?

• a.8,000 VA
• b.9,600 VA✓
• c.16,000 VA
• d.10,400 VA

16 kW is 4 kW over 12 kW, so add 5% x 4 = 20% to the 8-kW base: 8,000 x 1.20 = 9,600 VA.

A dwelling has one 4-kW electric clothes dryer. What value must be used as the dryer demand load in the service calculation?

• a.4,000 VA
• b.4,500 VA
• c.5,000 VA✓
• d.5,500 VA

The dryer load is the nameplate rating or 5,000 VA, whichever is larger. Since 4,000 VA is below 5,000 VA, 5,000 VA must be used.2023 NEC 220.54

A dwelling has four fastened-in-place appliances (dishwasher, disposal, water heater, compactor) totaling 6,000 VA. What is the demand load after applying the fastened-appliance demand factor?

• a.6,000 VA
• b.3,000 VA
• c.7,500 VA
• d.4,500 VA✓

Where four or more fastened-in-place appliances are on the same feeder, a 75% demand factor may be applied: 6,000 x 0.75 = 4,500 VA.2023 NEC 220.53

A dwelling's total calculated load is 24,000 VA on a 240-V, single-phase service. What is the calculated service current?

• a.100 A✓
• b.120 A
• c.83 A
• d.167 A

Current equals volt-amperes divided by voltage: 24,000 VA / 240 V = 100 A.

Using the 75 C column, what is the smallest copper conductor rated to carry a 100-A service load?

• a.#4 AWG
• b.#3 AWG✓
• c.#2 AWG
• d.#1 AWG

At 75 C, #4 Cu is rated 85 A and #3 Cu is rated 100 A. The #3 AWG copper is the smallest conductor that meets the 100-A requirement.2023 NEC Table 310.16

For a 200-A dwelling service using the 83% conductor allowance, what is the smallest copper ungrounded conductor (75 C) permitted for the main power feeder?

• a.#3/0 AWG
• b.#1/0 AWG
• c.#2/0 AWG✓
• d.#4/0 AWG

200 A x 0.83 = 166 A required ampacity. At 75 C, #2/0 Cu is rated 175 A, which satisfies 166 A, so #2/0 is the smallest permitted.2023 NEC 310.12

An electric range has a Column C demand of 8,000 VA. Using the 70% neutral demand for ranges, what is the range contribution to the feeder neutral load?

• a.8,000 VA
• b.4,000 VA
• c.7,000 VA
• d.5,600 VA✓

The feeder neutral for a household range may be figured at 70% of the range demand: 8,000 x 0.70 = 5,600 VA.

From the motor full-load current table, what is the full-load current of a 25-HP, 480-V, three-phase induction motor?

• a.34 A✓
• b.40 A
• c.28 A
• d.42 A

The table value for a 25-HP, 460-480-V three-phase motor is 34 A. Table full-load current (FLC), not nameplate, is used for conductor and protection sizing.2023 NEC Table 430.250

A single continuous-duty motor has a table full-load current of 34 A. What minimum conductor ampacity is required for its branch circuit?

• a.34 A
• b.42.5 A✓
• c.40 A
• d.50 A

Motor branch-circuit conductors must be at least 125% of the FLC: 34 A x 1.25 = 42.5 A minimum ampacity.2023 NEC 430.22

A motor with a service factor of 1.15 has a nameplate full-load current of 34 A. What is the maximum overload protection setting at 125%?

• a.34 A
• b.39.1 A
• c.42.5 A✓
• d.45.9 A

For a motor with service factor 1.15 or greater, overload is set at up to 125% of nameplate FLA: 34 x 1.25 = 42.5 A.2023 NEC 430.32

For a motor with a 34-A full-load current, what is the maximum inverse-time circuit breaker for branch-circuit short-circuit and ground-fault protection (250%, then next higher standard size)?

• a.70 A
• b.80 A
• c.100 A
• d.90 A✓

Inverse-time breaker: 250% of FLC = 34 x 2.50 = 85 A. Where this does not correspond to a standard size, the next higher standard rating (90 A) is permitted.2023 NEC 430.52

A feeder supplies three motors with full-load currents of 34 A, 28 A, and 22 A. What minimum conductor ampacity is required for the feeder?

• a.92.5 A✓
• b.105 A
• c.84 A
• d.110 A

Feeder ampacity = 125% of the largest motor FLC plus the sum of the others: (34 x 1.25) + 28 + 22 = 42.5 + 50 = 92.5 A.2023 NEC 430.24

What is the full-load primary current of a 75-kVA, 480-V, three-phase transformer?

• a.156 A
• b.90 A✓
• c.104 A
• d.72 A

Three-phase current = VA / (1.732 x V): 75,000 / (1.732 x 480) = 90.2 A, about 90 A.

What is the full-load secondary current of a 75-kVA, three-phase transformer with a 208-V secondary?

• a.156 A
• b.180 A
• c.208 A✓
• d.90 A

Secondary current = 75,000 / (1.732 x 208) = 208.2 A, about 208 A.

A 75-kVA transformer has a 90-A primary current (over 9 A). With primary-only protection at 125% max, what is the primary overcurrent device rating (next higher standard permitted)?

• a.110 A
• b.100 A
• c.150 A
• d.125 A✓

125% of 90 A = 112.5 A. Where this does not match a standard rating, the next higher standard device (125 A) is permitted for primary-only protection.2023 NEC 450.3(B)

A 120-V branch circuit carries 16 A over a one-way run of 80 ft using #12 Cu (circular mils = 6,530, K = 12.9). What is the approximate voltage drop?

• a.5.1 V✓
• b.3.0 V
• c.2.5 V
• d.7.4 V

Single-phase VD = (2 x K x I x L) / CM = (2 x 12.9 x 16 x 80) / 6,530 = 33,024 / 6,530 = 5.06 V.

Using the previous circuit (5.06-V drop on a 120-V circuit), what is the approximate percent voltage drop?

• a.2.1%
• b.4.2%✓
• c.6.0%
• d.3.0%

Percent VD = 5.06 / 120 = 0.042 = 4.2%, which exceeds the 3% recommended for branch circuits.

A 208-V three-phase feeder carries 40 A over 150 ft using #6 Cu (CM = 26,240, K = 12.9). What is the approximate voltage drop?

• a.3.0 V
• b.7.2 V
• c.5.1 V✓
• d.9.0 V

Three-phase VD = (1.732 x K x I x L) / CM = (1.732 x 12.9 x 40 x 150) / 26,240 = 134,050 / 26,240 = 5.11 V.

For a 112.5-kVA, 208-V, three-phase transformer with 2% impedance, what is the approximate available fault current at the secondary terminals (infinite primary)?

• a.6,250 A
• b.20,000 A
• c.10,000 A
• d.15,617 A✓

Secondary FLA = 112,500 / (1.732 x 208) = 312.3 A. Isc = FLA / %Z = 312.3 / 0.02 = 15,617 A.

A 45-kVA, 208-V, three-phase transformer has 2% impedance. What is the approximate available fault current at its secondary (infinite primary)?

• a.6,245 A✓
• b.3,120 A
• c.12,500 A
• d.9,000 A

Secondary FLA = 45,000 / (1.732 x 208) = 124.9 A. Isc = 124.9 / 0.02 = 6,245 A.

Six current-carrying THHN conductors share one raceway. If the 90 C ampacity of #6 Cu is 75 A, what is the adjusted ampacity after the fill adjustment factor for 4-6 conductors?

• a.75 A
• b.60 A✓
• c.55 A
• d.52.5 A

For 4 to 6 current-carrying conductors, apply an 80% adjustment factor: 75 A x 0.80 = 60 A.2023 NEC Table 310.15(C)(1)

A #3 Cu THHN conductor has a 90 C ampacity of 110 A. In a 50 C ambient (correction factor 0.82), what is the corrected ampacity?

• a.110 A
• b.100 A
• c.90 A✓
• d.82 A

Corrected ampacity = 110 A x 0.82 = 90.2 A, about 90 A, before comparing to the termination temperature limit.2023 NEC Table 310.15(B)(1)

A #2 Cu THHN (90 C ampacity 130 A) runs with 6 current-carrying conductors (0.80 factor) in a 40 C ambient (0.91 factor). What is the adjusted-and-corrected ampacity?

• a.130 A
• b.115 A
• c.104 A
• d.95 A✓

Apply both factors to the 90 C ampacity: 130 x 0.80 x 0.91 = 94.6 A, about 95 A.

An office has 45 general-use receptacle outlets. At 180 VA per outlet, what is the receptacle load before demand factors?

• a.8,100 VA✓
• b.4,500 VA
• c.9,000 VA
• d.5,400 VA

Each general-use receptacle outlet is figured at 180 VA: 45 x 180 = 8,100 VA.2023 NEC 220.14(I)

A commercial building has a 30,000-VA receptacle load. Applying the demand (first 10 kVA at 100%, remainder at 50%), what is the demand load?

• a.30,000 VA
• b.20,000 VA✓
• c.15,000 VA
• d.25,000 VA

First 10,000 VA at 100% = 10,000; remaining 20,000 at 50% = 10,000. Total demand = 20,000 VA.

What is the maximum number of service disconnecting means permitted for a single set of service-entrance conductors (each in a separate enclosure)?

• a.One
• b.Four
• c.Six✓
• d.Eight

A service is limited to a maximum of six disconnecting means. In the 2023 NEC each of the up-to-six disconnects must be in a separate enclosure or be part of listed equipment.2023 NEC 230.71

A service uses #2/0 Cu ungrounded conductors. What is the minimum copper grounding electrode conductor?

• a.#8 AWG
• b.#6 AWG
• c.#2 AWG
• d.#4 AWG✓

For service conductors over 1/0 through 3/0 Cu, the table requires a #4 Cu grounding electrode conductor.2023 NEC Table 250.66

Where the grounding electrode conductor connects only to a made ground rod, what is the largest copper conductor size ever required?

• a.#6 AWG✓
• b.#4 AWG
• c.#8 AWG
• d.#2 AWG

The portion of the GEC connecting solely to a rod, pipe, or plate electrode need not be larger than #6 Cu.2023 NEC 250.66(A)

A branch circuit is protected by a 100-A overcurrent device. What is the minimum copper equipment grounding conductor?

• a.#10 AWG
• b.#8 AWG✓
• c.#6 AWG
• d.#4 AWG

The equipment grounding conductor table requires #8 Cu for an overcurrent device rating up to 100 A.2023 NEC Table 250.122

A feeder is protected by a 400-A overcurrent device. What is the minimum copper equipment grounding conductor?

• a.#6 AWG
• b.#4 AWG
• c.#3 AWG✓
• d.#1 AWG

For a 400-A overcurrent device the table requires #3 Cu for the equipment grounding conductor.2023 NEC Table 250.122

A service has 500-kcmil Cu ungrounded conductors per phase. What is the minimum copper grounded (neutral) service conductor for bonding purposes?

• a.#4 AWG
• b.#2 AWG
• c.#1 AWG
• d.1/0 AWG✓

The grounded service conductor must be at least the size in Table 250.102(C)(1); for 500-kcmil Cu phase conductors that value is 1/0 Cu.2023 NEC Table 250.102(C)(1)

Service phase conductors total 1,500 kcmil Cu per phase (over 1,100 kcmil). Using the 12.5% rule, what is the minimum copper main bonding jumper?

• a.4/0 AWG✓
• b.3/0 AWG
• c.250 kcmil
• d.2/0 AWG

Above 1,100 kcmil, the main bonding jumper is at least 12.5% of the phase area: 0.125 x 1,500 = 187.5 kcmil, so 4/0 Cu (211.6 kcmil) is the smallest that qualifies.2023 NEC 250.28(D)

A panelboard is rated 225 A. What is the maximum rating of the overcurrent device that may protect it?

• a.200 A
• b.225 A✓
• c.250 A
• d.400 A

Each panelboard must be protected by an overcurrent device rated no more than the panelboard rating, so 225 A is the maximum.2023 NEC 408.36

Which of the following is the next standard overcurrent device rating above 95 A?

• a.90 A
• b.110 A
• c.100 A✓
• d.125 A

Standard ratings include 90, 100, 110, and 125 A. The next standard size above 95 A is 100 A.2023 NEC 240.6

Absent a specific exception, what is the maximum overcurrent protection for a #12 Cu conductor?

• a.30 A
• b.25 A
• c.15 A
• d.20 A✓

Under the small-conductor rule, #12 Cu is limited to a maximum overcurrent device of 20 A.2023 NEC 240.4(D)

Absent a specific exception, what is the maximum overcurrent protection for a #10 Cu conductor?

• a.30 A✓
• b.25 A
• c.20 A
• d.40 A

The small-conductor rule limits #10 Cu to a maximum 30-A overcurrent device.2023 NEC 240.4(D)

A conductor has an allowable ampacity of 115 A, which is not a standard rating. Under the next-standard-size rule (600 A or less), what is the largest permitted overcurrent device?

• a.110 A
• b.125 A✓
• c.150 A
• d.100 A

When ampacity does not match a standard rating and conditions are met, the next higher standard device (125 A) is permitted for 800-A or smaller circuits.2023 NEC 240.4(B)

What is the smallest conductor size generally permitted to be installed in parallel?

• a.#2 AWG
• b.#1 AWG
• c.1/0 AWG✓
• d.2/0 AWG

Conductors are generally permitted in parallel only in sizes 1/0 AWG and larger.2023 NEC 310.10(G)

Two paralleled sets of 500-kcmil Cu (75 C, 380 A each) supply one feeder. What is the combined ampacity before adjustment?

• a.500 A
• b.620 A
• c.380 A
• d.760 A✓

Paralleled conductor ampacities add: 380 A x 2 = 760 A total for the feeder.2023 NEC Table 310.16

What is the minimum service disconnecting-means rating for a one-family dwelling?

• a.100 A✓
• b.60 A
• c.125 A
• d.200 A

The service disconnecting means for a one-family dwelling must be rated at least 100 A, 3-wire.2023 NEC 230.79

What is the minimum vertical clearance of an overhead service drop (not over 300 V) above a residential driveway or sidewalk area limited to pedestrians?

• a.10 ft
• b.12 ft✓
• c.15 ft
• d.18 ft

Service-drop conductors up to 300 V to ground require 12 ft of clearance over residential property and driveways not subject to truck traffic.2023 NEC 230.24(B)

At a separately derived system such as a transformer, what conductor connects the grounded conductor to the system grounding electrode?

• a.Main bonding jumper
• b.Equipment bonding jumper
• c.System bonding jumper✓
• d.Grounding electrode conductor

The system bonding jumper connects the grounded conductor of a separately derived system to the supply-side equipment grounding/bonding at one point.2023 NEC 250.30(A)

An emergency system must be capable of supplying power to its loads within what maximum time after normal supply is lost?

• a.60 seconds
• b.30 seconds
• c.120 seconds
• d.10 seconds✓

Emergency systems must restore power to life-safety loads within 10 seconds of loss of the normal source.2023 NEC 700.12

A legally required standby system must supply its loads within what maximum time after loss of normal power?

• a.60 seconds✓
• b.10 seconds
• c.30 seconds
• d.120 seconds

Legally required standby systems must be able to supply their loads within 60 seconds of a normal-source failure.2023 NEC 701.12

Generator output conductors must have an ampacity of at least what percent of the nameplate current?

• a.100%
• b.115%✓
• c.125%
• d.110%

Generator conductors from the terminals to the first overcurrent device must be at least 115% of the nameplate current rating.2023 NEC 445.13

A feeder supplies a 60,000-VA, 208-V, three-phase load. What is the calculated feeder current?

• a.150 A
• b.200 A
• c.167 A✓
• d.144 A

Three-phase current = 60,000 / (1.732 x 208) = 166.6 A, about 167 A.

A 200-A busbar has a 200-A main breaker at one end. Using the 120% rule, what is the maximum back-fed inverter (PV) overcurrent device at the opposite end?

• a.20 A
• b.60 A
• c.30 A
• d.40 A✓

120% of the 200-A busbar = 240 A. Subtract the 200-A main: 240 - 200 = 40 A maximum for the back-fed supply breaker.2023 NEC 705.12(B)

A single made electrode (ground rod) must be supplemented unless its resistance to earth does not exceed what value?

• a.25 ohms✓
• b.5 ohms
• c.10 ohms
• d.1 ohm

A single rod, pipe, or plate electrode must be supplemented by a second electrode unless it has a resistance to earth of 25 ohms or less.2023 NEC 250.53(A)

A metal underground water pipe qualifies as a grounding electrode if it is in direct contact with earth for at least how many feet?

• a.10 ft
• b.5 ft✓
• c.3 ft
• d.1 ft

A metal underground water pipe electrode must have at least 10 ft of contact with earth (bonding connection made within 5 ft of entry).2023 NEC 250.52(A)(1)

A concrete-encased electrode (Ufer) must consist of at least how many feet of #4 or larger rebar or bare #4 Cu conductor?

• a.10 ft
• b.15 ft
• c.20 ft✓
• d.25 ft

A concrete-encased electrode requires at least 20 ft of 1/2-in (or larger) rebar or 20 ft of bare #4 Cu encased in the concrete footing/foundation.2023 NEC 250.52(A)(3)

A location where ignitable concentrations of flammable gases or vapors exist under normal operating conditions is classified as:

• a.Class II, Division 1
• b.Class III
• c.Class I, Division 2
• d.Class I, Division 1✓

Class I covers flammable gases/vapors; Division 1 means ignitable concentrations can exist under normal operation, so it is Class I, Division 1.2023 NEC 500.5(B)(1)

A location made hazardous by combustible dust is classified as which class?

• a.Class II✓
• b.Class I
• c.Class III
• d.Class IV

Class II locations are those hazardous because of the presence of combustible dust.2023 NEC 500.5(C)

In a Class I, Division 1 location, a sealing fitting must be installed within what distance of an enclosure containing arcing devices?

• a.24 in
• b.18 in✓
• c.12 in
• d.36 in

Seals are required within 18 in of enclosures that contain devices which may produce arcs, sparks, or high temperatures.2023 NEC 501.15(A)

What is the minimum number of receptacles required at a general care (Category 2) patient bed location?

• a.4
• b.6
• c.8✓
• d.14

General care patient bed locations require a minimum of 8 receptacles, served from the normal and/or essential systems.2023 NEC 517.18(B)

What is the minimum number of receptacles required at a critical care (Category 1) patient bed location?

• a.8
• b.10
• c.12
• d.14✓

Critical care patient bed locations require a minimum of 14 receptacles.2023 NEC 517.19(B)

The equipotential bonding grid around a permanently installed pool must use a solid copper conductor no smaller than:

• a.#8 AWG✓
• b.#6 AWG
• c.#10 AWG
• d.#4 AWG

Pool equipotential bonding must use an insulated, covered, or bare solid copper conductor not smaller than #8 AWG.2023 NEC 680.26(B)

A required convenience receptacle for a dwelling pool must be located not less than what distance from the inside pool wall?

• a.10 ft
• b.6 ft✓
• c.5 ft
• d.8 ft

At least one receptacle is required between 6 ft and 20 ft from the inside wall; the minimum setback is 6 ft.2023 NEC 680.22(A)

A wet-niche underwater luminaire operating without GFCI protection is limited to a maximum of:

• a.120 V
• b.24 V
• c.15 V✓
• d.30 V

Underwater luminaires must be GFCI protected unless they operate at not more than the low-voltage contact limit of 15 V.2023 NEC 680.23(A)

A motor disconnecting means must have an ampere rating of at least what percent of the motor full-load current?

• a.100%
• b.110%
• c.125%
• d.115%✓

The disconnecting means for a motor must be rated at least 115% of the motor full-load current.2023 NEC 430.110(A)

A single hermetic refrigerant motor-compressor has a rated-load current of 24 A. What minimum branch-circuit conductor ampacity is required?

• a.30 A✓
• b.24 A
• c.36 A
• d.28 A

Conductors to a single motor-compressor must be at least 125% of the rated-load or branch-circuit selection current: 24 x 1.25 = 30 A.2023 NEC 440.32

A hermetic compressor has a rated-load current of 24 A. What is the maximum branch-circuit short-circuit and ground-fault device at 175% (next standard size)?

• a.40 A
• b.45 A✓
• c.50 A
• d.60 A

175% of 24 A = 42 A; the next standard overcurrent size is 45 A, which is the maximum permitted for short-circuit/ground-fault protection.2023 NEC 440.22(A)

Which nameplate value on an air-conditioning unit is used to size the branch-circuit conductors?

• a.Maximum overcurrent protection
• b.Nameplate horsepower
• c.Minimum circuit ampacity✓
• d.Rated-load amps only

Conductors are sized to the marked minimum circuit ampacity (MCA); the maximum overcurrent protective device (MOCP) sizes the breaker or fuse.2023 NEC 440.4

A Class 2 power-limited circuit at 30 V or less is limited to a maximum power of:

• a.1,000 VA
• b.250 VA
• c.500 VA
• d.100 VA✓

Class 2 circuits are inherently limited low-energy circuits; a typical alternating-current source limit is 100 VA at up to 30 V for reliable low-energy protection.2023 NEC Chapter 9 Table 11(B)

Cables listed for power-limited fire alarm use are marked with which type designation?

• a.FPL✓
• b.CL2
• c.CMR
• d.TC

Power-limited fire alarm cables carry the FPL family markings (FPL, FPLR riser, FPLP plenum).2023 NEC 760.179

Two 10-HP, 460-V motors (14 A each) are supplied by one feeder. What minimum feeder conductor ampacity is required?

• a.28 A
• b.31.5 A✓
• c.35 A
• d.25 A

125% of the largest motor plus the other: (14 x 1.25) + 14 = 17.5 + 14 = 31.5 A.2023 NEC 430.24

A motor without a marked service factor (or with SF under 1.15) has a full-load current of 28 A. What is the maximum overload protection at 115%?

• a.35 A
• b.28 A
• c.32.2 A✓
• d.30 A

For motors with a service factor less than 1.15, overload protection is limited to 115% of nameplate FLA: 28 x 1.15 = 32.2 A.2023 NEC 430.32(A)

Which wiring method is acceptable in a Class I, Division 2 location?

• a.Type NM
• b.Type AC
• c.Nonmetallic Romex
• d.Type MC with listed fittings✓

Class I, Division 2 permits methods such as threaded rigid metal conduit and Type MC cable with listed fittings; ordinary NM/AC cable is not permitted.2023 NEC 501.10(B)

A required branch circuit that supplies a sign or outline lighting system must be rated at least:

• a.20 A✓
• b.15 A
• c.30 A
• d.40 A

Each commercial building must have at least one dedicated 20-A branch circuit for a sign or outline lighting outlet.2023 NEC 600.5(B)

Low-voltage lighting systems covered by Article 411 are limited to a maximum circuit voltage of:

• a.24 V
• b.30 V✓
• c.15 V
• d.12 V

Article 411 low-voltage lighting systems operate at not more than 30 V (or 60 V DC for wet contact limits), commonly through a listed power supply.2023 NEC 411.5

Electrical equipment supplying a decorative fountain must have what protection?

• a.AFCI
• b.Surge protection
• c.GFCI✓
• d.Isolation transformer only

All electrical equipment associated with fountains, including luminaires and pumps, must be protected by a ground-fault circuit interrupter.2023 NEC 680.51(A)

The equipotential plane bonding conductor in an agricultural building must be:

• a.#8 Cu only if insulated
• b.#6 Cu maximum
• c.Insulated conductor only
• d.Copper conductor not smaller than #8✓

Bonding of the equipotential plane in agricultural buildings uses a copper conductor not smaller than #8 AWG, solid or the equivalent.2023 NEC 547.10

A motor feeder supplies motors whose largest branch device is 90 A, plus other motors with 50 A total full-load current. What is the maximum feeder short-circuit/ground-fault device (not to exceed the sum, next standard down)?

• a.125 A✓
• b.150 A
• c.175 A
• d.110 A

The feeder device may not exceed the largest branch-circuit device (90 A) plus the other FLCs (50 A) = 140 A; the largest standard rating not exceeding 140 A is 125 A.2023 NEC 430.62

A load draws 80 kW of real power and 100 kVA of apparent power. What is the power factor?

• a.1.0
• b.0.8✓
• c.0.6
• d.0.9

Power factor = real power / apparent power = 80 kW / 100 kVA = 0.8.

For a load of 80 kW real and 100 kVA apparent, what is the reactive power?

• a.80 kVAR
• b.100 kVAR
• c.60 kVAR✓
• d.40 kVAR

Reactive power = sqrt(kVA^2 - kW^2) = sqrt(100^2 - 80^2) = sqrt(3,600) = 60 kVAR.

What is the real power of a three-phase load at 480 V, 50 A, and 0.85 power factor?

• a.24,960 W
• b.41,568 W
• c.30,000 W
• d.35,326 W✓

P = 1.732 x V x I x PF = 1.732 x 480 x 50 x 0.85 = 35,326 W.

In a balanced wye (star) three-phase system, the line current is:

• a.Equal to the phase current✓
• b.1.732 times the phase current
• c.0.577 times the phase current
• d.2 times the phase current

In a wye connection the same conductor carries phase and line current, so line current equals phase current.

In a balanced delta three-phase system, the line current equals:

• a.The phase current
• b.1.732 times the phase current✓
• c.0.577 times the phase current
• d.3 times the phase current

In a delta connection the line current is the square root of 3 (1.732) times the phase (winding) current.

In a 208Y/120-V wye system, what is the phase (line-to-neutral) voltage?

• a.208 V
• b.240 V
• c.120 V✓
• d.277 V

Line-to-neutral voltage = line-to-line / 1.732 = 208 / 1.732 = 120 V.

In a 480Y/277-V system, what is the line-to-neutral voltage?

• a.120 V
• b.240 V
• c.208 V
• d.277 V✓

Line-to-neutral = 480 / 1.732 = 277 V.

An 80-kW load at 0.80 power factor is to be corrected to 0.95. How many kVAR of capacitance are required (tan 36.87 = 0.75, tan 18.19 = 0.329)?

• a.33.7 kVAR✓
• b.60 kVAR
• c.48 kVAR
• d.20 kVAR

Qc = kW x (tan(theta1) - tan(theta2)) = 80 x (0.750 - 0.329) = 80 x 0.421 = 33.7 kVAR.

In a three-phase, four-wire wye system serving nonlinear loads, which harmonic order adds arithmetically in the neutral?

• a.2nd
• b.3rd✓
• c.5th
• d.7th

Triplen harmonics, principally the 3rd, are in phase across all three phases and add in the neutral rather than canceling.

On a feeder with significant harmonic (nonlinear) load, the neutral conductor is treated as:

• a.Not a current-carrying conductor
• b.A half current-carrying conductor
• c.A current-carrying conductor✓
• d.An ignored conductor

Where the major portion of the load is nonlinear, the neutral carries harmonic current and must be counted as a current-carrying conductor for adjustment.2023 NEC 310.15(E)

A three-phase panel has phase loads of A = 40 A, B = 30 A, C = 20 A. What is the ideal balanced current per phase?

• a.40 A
• b.20 A
• c.25 A
• d.30 A✓

Total = 40 + 30 + 20 = 90 A; balanced across three phases = 90 / 3 = 30 A per phase.

A single-line (one-line) diagram represents an electrical system by:

• a.One line for each circuit or set of conductors✓
• b.Each individual conductor drawn separately
• c.The physical layout of raceways
• d.Only the branch-circuit wiring

A one-line diagram uses a single line and standard symbols to represent circuits and equipment, simplifying analysis of the power system.

A transformer steps 480 V down to 120 V. What is its turns (voltage) ratio?

• a.2:1
• b.4:1✓
• c.1:4
• d.8:1

Turns ratio = primary voltage / secondary voltage = 480 / 120 = 4:1.

A transformer has a 4:1 turns ratio and a 10-A primary current. What is the secondary current (ideal)?

• a.10 A
• b.2.5 A
• c.40 A✓
• d.20 A

Current is inversely proportional to the turns ratio: Is = Ip x (Np/Ns) = 10 x 4 = 40 A.

An AC circuit at 240 V draws 12 A. What is the circuit impedance?

• a.2 ohms
• b.0.05 ohms
• c.288 ohms
• d.20 ohms✓

By Ohm's law for AC, Z = V / I = 240 / 12 = 20 ohms.

A continuous load draws 40 A. At what minimum ampacity must the branch-circuit conductors and overcurrent device be rated?

• a.50 A✓
• b.40 A
• c.32 A
• d.45 A

Continuous loads require 125% sizing: 40 A x 1.25 = 50 A for the conductors and overcurrent device.2023 NEC 210.20(A)

The demand factor of a system is defined as:

• a.A value always greater than 1
• b.Maximum demand divided by total connected load✓
• c.Connected load divided by maximum demand
• d.Always equal to 1

Demand factor = maximum demand / total connected load; it is 1 or less and reflects load diversity.

What are the commonly recommended maximum voltage-drop limits for a branch circuit and for the combined feeder plus branch circuit?

• a.5% and 8%
• b.2% and 4%
• c.3% and 5%✓
• d.1% and 3%

The informational recommendation is 3% maximum on a branch circuit and 5% maximum for feeder plus branch circuit combined.

For equipment operating at 0-150 V to ground under Condition 1, what is the minimum depth of working space in front of the equipment?

• a.2 ft
• b.2.5 ft
• c.4 ft
• d.3 ft✓

Condition 1 (exposed live parts on one side, no grounded parts opposite) requires a minimum working clearance of 3 ft for 0-150 V.2023 NEC 110.26(A)(1)

What is the minimum required width of working space in front of electrical equipment?

• a.30 in or the width of the equipment, whichever is greater✓
• b.24 in
• c.36 in always
• d.18 in

The working space width must be at least 30 in or the width of the equipment, whichever is greater, and must permit a 90-degree door opening.2023 NEC 110.26(A)(2)

What is the minimum headroom (height) of working space about electrical equipment such as panelboards?

• a.6 ft
• b.6.5 ft✓
• c.7 ft
• d.8 ft

The minimum headroom of working space is 6.5 ft (or the height of the equipment, whichever is greater).2023 NEC 110.26(A)(3)

The dedicated equipment space above a panelboard extends how far above the equipment (or to a structural ceiling if lower)?

• a.3 ft
• b.4.5 ft
• c.6 ft✓
• d.7 ft

The dedicated electrical space extends from the equipment to 6 ft above it, or to a structural ceiling if lower, and must be kept clear of foreign systems.2023 NEC 110.26(E)(1)

Equipment rated at what current or more requires two entrances to and egress from the working space when the space is large or contains overcurrent devices?

• a.800 A
• b.600 A
• c.1000 A
• d.1200 A✓

For equipment rated 1,200 A or more and over 6 ft wide, two entrances/egress paths to the working space are required.2023 NEC 110.26(C)(2)

For a circuit rated 100 A or less, conductor ampacity is generally based on which temperature column unless the equipment is listed otherwise?

• a.60 C✓
• b.75 C
• c.90 C
• d.105 C

Terminations on equipment rated 100 A or less are based on the 60 C column unless the equipment and conductors are listed for a higher temperature.2023 NEC 110.14(C)(1)

For circuits rated over 100 A, conductor ampacity for terminations is generally based on which temperature column?

• a.60 C
• b.75 C✓
• c.90 C
• d.Nameplate only

Terminations on equipment over 100 A are based on the 75 C column unless listed and marked for a higher rating.2023 NEC 110.14(C)(1)

Which standard governs electrical safety-related work practices, including arc-flash and shock protection?

• a.NEC (NFPA 70)
• b.NFPA 72
• c.NFPA 70E✓
• d.OSHA 1910 only

NFPA 70E, Standard for Electrical Safety in the Workplace, covers safe work practices, arc-flash boundaries, and PPE selection.

Under safe electrical work practices, what is the preferred condition before working on or near exposed conductors?

• a.Wearing rubber gloves
• b.Energized with a permit
• c.Under observation
• d.An electrically safe (de-energized and verified) work condition✓

The safest and preferred approach is to place equipment in an electrically safe work condition: de-energize, lock out, and verify absence of voltage before work.

What is the primary purpose of a lockout/tagout (LOTO) procedure under Cal/OSHA?

• a.To isolate and control hazardous energy during servicing✓
• b.To label panel directories
• c.To test GFCI devices
• d.To install ground rods

LOTO isolates and controls hazardous energy sources so equipment cannot be re-energized while workers are servicing it.

During electrical construction, a rough-in (rough) inspection is generally performed:

• a.After energizing the system
• b.Before wiring is concealed or covered✓
• c.Only at final occupancy
• d.After the final inspection

The rough inspection occurs after wiring is installed but before walls or wiring are covered, so the inspector can verify concealed work.

Who is responsible for interpreting and enforcing the requirements of the NEC?

• a.The equipment manufacturer
• b.The NFPA
• c.The authority having jurisdiction (AHJ)✓
• d.The serving utility

The authority having jurisdiction enforces the Code, makes interpretations, and grants any special permission where allowed.2023 NEC 90.4

The NEC generally does not cover which of the following installations?

• a.Dwelling branch circuits
• b.Commercial feeders
• c.Industrial services
• d.Utility-owned generation and distribution under exclusive utility control✓

The Code does not apply to installations under the exclusive control of an electric utility for generation, transmission, or distribution of power.2023 NEC 90.2(B)

Service equipment (other than dwellings) must be field marked with what value related to fault protection?

• a.Maximum available fault current✓
• b.The panel interrupting rating only
• c.Installation date only
• d.Phase rotation

Service equipment must be legibly field marked with the maximum available fault current and the date of the calculation.2023 NEC 110.24(A)

Equipment likely to be examined or serviced while energized must carry what type of field-applied marking?

• a.Voltage rating only
• b.An arc-flash hazard warning label✓
• c.Phase-sequence label
• d.Equipment grounding conductor size

An arc-flash warning label must be applied to warn qualified persons of the potential arc-flash hazard before energized examination or servicing.2023 NEC 110.16