TheoryElectrician Practice Questions
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Electrician Questions
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Q1Circuit breakers and switches containing fuses shall be located so that they may be operated from a readily accessible place. They shall be installed such that the center of the grip of the operating handle of the switch or circuit breaker, when in its highest position, is not more than <code>________</code> above the floor or working platform.
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✓ Correct answer: 6 feet 7 inches
240.24. The maximum height above the floor or the working platform that a switch or circuit breaker is allowed to be installed is 6 feet 7 inches.<br/><br/>This is measured from the center of the grip of the operating handle when in its highest position.
Q2All 125-volt, single-phase receptacles not exceeding 30 amperes located at least within <code>________</code> measured horizontally of the inside wall of a hydromassage tub shall be protected by a ground-fault circuit interrupter.
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✓ Correct answer: 6 feet
The intent of this rule, addressed in Section 680.71, is to prevent a shock hazard in the area surrounding a hydromassage tub that may have the presence of water. <br/><br/>Therefore, all 125-volt, single-phase receptacles of not more than 30 amperes and located within 6 ft. of the tub are to be GFCI protected.
Q3The NEC mandates specific branch circuits, receptacle outlets and utilization equipment to be provided with a ground-fault circuit interrupter (GFCI); this device is intended <code>________</code>.
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✓ Correct answer: for the protection of personnel
Article 100, where definitions are found, reveals a ground-fault circuit interrupter is a device intended for the protection of personnel that functions to de-energize a circuit when a ground-fault occurs.
Q4Circuit breakers used as switches in high-intensity discharge lighting circuits shall be listed and shall be marked as:
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Q5Where an ac transformer arc welder has a 50-ampere rated primary current and a 60 percent duty cycle, determine the minimum size copper 60 deg. C rated conductors required to supply this welder.
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✓ Correct answer: 8 AWG
The loads on transformer arc welders are considered intermittent. <br/><br/>Therefore, the minimum ampacity of the branch-circuit conductors is permitted to be determined by applying the percentage values shown in Table 630.11(A). This calculation is done by selecting the appropriate factor from the table, based on the duty cycle and type of welder, then multiply by the value of the welder rated primary current. The conductors are to be selected from Table 310.16.<br/><br/>.78 (duty cycle factor) x 50 amperes (primary current) = 39 amperes<br/><br/>Table 310.16 requires size 8 AWG 60°C rated conductors.
Q6Which of the following listed conductor insulations is oil resistant?
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✓ Correct answer: MTW
Table 310.4(1) shows conductors with MTW insulation to be oil resistant.
Q7When a 2-wire circuit is derived from two ungrounded conductors of a multiwire circuit and is used with switched lampholders, the switching device required is to be:
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Q8Determine the voltage drop on a branch circuit given the following related information:<br/><ul><li>current = 5 amperes</li><li>conductor length = 300 ft.</li><li>conductor resistance = 4 ohms per 1,000 feet</li></ul>
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✓ Correct answer: 6 volts
To determine the voltage drop on this circuit, first find the resistance total with the information given in the question:<br/><br/>Resistance = 4 ohms ÷ 1000 ft. = .004 ohms per ft.<br/><br/>.004 ohms x 300 ft. = 1.2 ohms total resistance<br/><br/>Next, apply the voltage drop formula, VD = I X R:<br/><br/>VD= 5 amperes x 1.2 ohms = 6 volts dropped.
Q9The maximum approved electrical trade size for LFNC is <code>________</code>:
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Q10The branch-circuit conductors supplying fixed electric space-heating equipment and any associated motors shall be sized not smaller than <code>________</code> of the load.
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✓ Correct answer: 125%
Fixed electric space-heating equipment is covered in Article 424. <br/><br/>Section 424.4(B) specifically requires branch-circuit conductors for fixed electric space-heating equipment and any associated motors to be sized not smaller than 125% of the load. <br/><br/>This mandate is necessary to protect conductors and overcurrent devices, particularly those in panelboards and load centers, from overheating during periods of prolonged operation.
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