Journeyman Electrician (2024/25Nec)
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Conductors with _____ marked on the insulation are NOT approved for use in a wet II II II II II II II II II II II II II II
location.
II
a. THW II
b. THHW II
c. THHN II
d. THWN - THHN
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As shown in Table 310.104(A), conductors with THHN insulation are approved for use in
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dry and damp locations only and conductors with THWN, THHW, and THW insulation are
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recognized for use in dry and wet locations.
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Given: A one-family dwelling unit with a demand load of 200 amperes is supplied with a
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120/240 volt, single-phase, electrical system from the local utility company. What is the
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MINIMUM size aluminum THW conductors required for use as service-entrance
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conductors for this residence?
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a. 1/0 AWGII II
b. 4/0 AWGII II
c. 3/0 AWGII II
d. 2/0 AWG - 4/0 AWG
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Section 310.15(B)(7)(1) permits one-family dwelling 120/240 volt, single-phase, service-
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entrance conductors to be sized at an ampacity of not less than 83% of the service rating.
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Therefore, 200 amperes x 83% = 166 amperesTable 310.15(B)(16) indicates size 4/0
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AWG THW aluminum conductors with an allowable ampacity of 180 amperes should be
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selected for this dwelling.
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Where a 150 kVA, single-phase transformer having a secondary voltage of 120/240 is
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installed at a multi-family dwelling, the full-load current rating, in amperes, of the
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secondary is _____.
II II II
a. 625 amperes
II II
b. 265 amperes
II II
c. 526 amperes
II II
d. 1250 amperes - 625 ampreres
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To find the full-load current rating of the single-phase transformer apply the single-phase
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current formula as shown:
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I = (150 kVA x 1000) / 240 volts = 15,000/240 = 625 amperes
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Which one of the following listed circuit breakers is NOT a standard ampere rating?a. 75
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amperes
II
b. 90 amperes
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c. 110 amperes
II II
d. 225 amperes - 75 amperes
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, Table 240.6(A) illustrates the standard ampere ratings for fuses and circuit breakers. A
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circuit breaker with an ampere rating of 75 amperes is not a standard ampere rating.
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The MINIMUM length of free conductor to be left at each junction box for the purpose of
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splicing conductors, or making connections to luminaires or devices shall be _____ .a. 4
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inches
II
b. 10 inches
II II
c. 8 inches
II II
d. 6 inches - 6 inches
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As per Section 300.14 at least 6 in. of free conductor is to be left at each junction box for
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splices or the connection of luminaires or devices. The intent of this rule is to ensure
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enough conductor slack for the terminal connections or splices to be made easily.
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In general, overhead service-drop conductors shall NOT be smaller than _____.
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a. 2 AWG copper
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b. 4 AWG copper
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c. 6 AWG copper
II II II
d. 8 AWG copper - d. 8 AWG copper
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Section 230.23(B) requires overhead service-drop conductors to be not smaller than 8
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AWG copper or 6 AWG aluminum or copper-clad aluminum. Do not get service-drop
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conductors, the overhead conductors between the utility electric supply system and the
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service point, confused with the service-entrance conductors, the conductors from the
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service point from the utility company to the service disconnecting means.
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When a galvanized eye-bolt is to be used as the point of attachment for an electrical
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service, the NEC requires the eye-bolt to be installed NOT less than _____ above finished
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grade.
II
a. 8 ft.II II
b. 10 ft.
II II
c. 12 ft.
II II
d. 15 ft. - 10 Ft
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The intent of Section 230.26 is to provide adequate vertical clearance of the conductors
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and prevent physical damage to the conductors and prevent persons from making
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accidental contact with the conductors which may create a shock hazard or electrocution.
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In no case shall the point of attachment of the service-drop conductors to be less than 10
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ft. above finished grade.
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Why is electrical continuity required for metallic conduit?
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a. To reduce voltage drop.
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b. To limit galvanic corrosion.
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c. To establish an effective ground-fault path and facilitate the operation of the overcurrent
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protective device.
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d. To reduce electrolysis. - To establish an effective ground-fault path and facilitate the
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operation of the overcurrent protective device.
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