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Arizona CR-11 Electrical Contractor EXAM WITH 300
QUESTIONS AND CORRECT DETAILED SOLUTIONS WITH
RATIONALES LATEST UPDATED VERSION THIS YEAR
Question 1 Which of the following expressions correctly represents Ohm's Law for a DC circuit? A) V = I × R B) I = V × R C) R = V ÷ I² D) P = V ÷ I Correct Answer: A Rationale: Ohm's Law states that voltage (V) equals current (I) multiplied by resistance (R) in a DC circuit. Question 2 Which unit is used to measure electrical capacitance? A) Ohm B) Farad
C) Henry D) Siemens Correct Answer: B Rationale: Capacitance is measured in farads (F). Ohms measure resistance, henrys measure inductance, and siemens measure conductance. Question 3 In an AC circuit, apparent power (S) is measured in kVA. Which formula calculates S for a three- phase system? A) S = V × I × √ B) S = V ÷ I C) S = P × PF D) S = V² ÷ R Correct Answer: A Rationale: Apparent power in a three-phase AC system equals line-to-line voltage times line current times √3.
Rationale: Power factor (PF) is the ratio of true power (watts) to apparent power (volt-amperes) in an AC circuit, ranging from 0 to 1. Question 6 What is the color code for the equipment grounding conductor in a 120/240 V residential system? A) Black B) White C) Bare copper or green D) Red Correct Answer: C Rationale: The equipment grounding conductor must be bare copper, green, or green with yellow stripes per NEC requirements. Question 7 In a series circuit, which of the following remains constant? A) Voltage
B) Current C) Resistance D) Power Correct Answer: B Rationale: In a series circuit, the current is the same through all components. Voltage divides across each component based on resistance. Question 8 In a parallel circuit, which of the following remains constant? A) Current B) Voltage C) Resistance D) Power Correct Answer: B Rationale: In a parallel circuit, the voltage is the same across all branches. Current divides among the branches based on resistance.
Question 11 What is the current drawn by a 1,200-watt heater connected to a 120-volt circuit? A) 5 A B) 10 A C) 15 A D) 20 A Correct Answer: B Rationale: Using the power formula, I = P ÷ V = 1,200 W ÷ 120 V = 10 A. Question 12 Which of the following is NOT a factor that affects the resistance of a conductor? A) Length B) Cross-sectional area C) Temperature D) Voltage Correct Answer: D
Rationale: Resistance depends on length (directly proportional), cross-sectional area (inversely proportional), material type, and temperature. Voltage does not affect resistance. Question 13 What is the maximum continuous load allowed on a 15-ampere branch circuit? A) 12 A B) 15 A C) 18 A D) 20 A Correct Answer: A Rationale: Continuous loads must not exceed 80% of the breaker rating: 0.8 × 15 A = 12 A. Question 14 What is the color code for the neutral conductor in a 120/240 V system? A) Black B) Green C) White or gray
Question 16 The peak voltage of a 120 V RMS AC waveform is approximately: A) 120 V B) 169.7 V C) 240 V D) 84.9 V Correct Answer: B Rationale: Peak voltage = RMS voltage × √2 = 120 V × 1.414 = 169.7 V. Question 17 Which instrument is used to measure electrical resistance? A) Voltmeter B) Ammeter C) Ohmmeter D) Wattmeter Correct Answer: C
Rationale: An ohmmeter measures resistance. A voltmeter measures voltage, an ammeter measures current, and a wattmeter measures power. Question 18 A transformer that increases voltage is called a: A) Step-down transformer B) Step-up transformer C) Isolation transformer D) Autotransformer Correct Answer: B Rationale: A step-up transformer increases voltage from the primary to the secondary winding. A step-down transformer decreases voltage. Question 19 What is the apparent power of a single-phase circuit with 120 V and 10 A? A) 1,200 W B) 1,200 VA
Question 21 Which NEC article governs the installation of service-entrance conductors? A) 230 B) 310 C) 300 D) 210 Correct Answer: A Rationale: NEC Article 230 governs the installation of service-entrance conductors and services. Question 22 In a single-phase 120 V branch circuit, a 15 A breaker is installed. What is the maximum continuous load allowed on this circuit? A) 12 A B) 15 A C) 18 A D) 20 A
Correct Answer: A Rationale: Continuous loads must not exceed 80% of the breaker rating: 0.8 × 15 A = 12 A. Question 23 A feeder is required to supply 30 kVA at 240 V three-phase. What is the approximate ampacity needed (ignoring power factor)? A) 72 A B) 60 A C) 85 A D) 100 A Correct Answer: A Rationale: I = P ÷ (√3 × V) = 30,000 VA ÷ (1.732 × 240 V) ≈ 72 A. Question 24 When sizing a feeder for a 30 A continuous load, which multiplier must be applied to the load current per NEC 210.19(A)(1)? A) 1.
Question 26 The voltage drop on a branch circuit should not exceed what percentage? A) 5% B) 3% C) 8% D) 10% Correct Answer: B Rationale: To ensure efficient operation and minimize losses, the industry recommends a maximum of 3% voltage drop for branch circuits. Question 27 What is the maximum voltage drop recommended for feeder and branch circuit combined? A) 3% B) 5% C) 8% D) 10% Correct Answer: B
Rationale: The total voltage drop for feeders and branch circuits combined should not exceed 5% (3% branch + 2% feeder). Question 28 How many 15-ampere general lighting circuits are required for a 2,000 sq ft residence? A) 1 B) 2 C) 3 D) 4 Correct Answer: C Rationale: General lighting load = 2,000 sq ft × 3 VA/sq ft = 6,000 VA. Circuits required = 6, VA ÷ (15 A × 120 V) = 6,000 ÷ 1,800 = 3.33, so at least 4 circuits are needed. Question 29 A dwelling unit has a connected load of 20,000 VA. What is the standard demand factor for the first 3,000 VA? A) 100%
Question 31 What is the minimum size copper conductor for a 100-ampere service? A) #8 AWG B) #6 AWG C) #4 AWG D) #2 AWG Correct Answer: C Rationale: According to NEC Table 310.15(B)(16), a 100-ampere service typically requires # AWG copper for 75°C rated conductors. Question 32 Service-entrance conductors must be sized to carry: A) 100% of the calculated load B) 125% of the calculated load C) 150% of the calculated load D) 80% of the calculated load Correct Answer: A
Rationale: Service-entrance conductors must be sized to carry 100% of the calculated load, but must also meet the minimum size requirements for the service rating. Question 33 The demand factor for electric ranges in a dwelling unit is found in which NEC article? A) Article 210 B) Article 220 C) Article 230 D) Article 240 Correct Answer: B Rationale: NEC Article 220 contains the demand factors and load calculations for branch circuits, feeders, and services, including electric ranges. Question 34 A 240-volt, 5 kW electric water heater draws approximately: A) 15.6 A B) 20.8 A
