NCCER Journeyman Electrician Practice Test
Questions and Answers
1.Conductors with marked on the insulation are NOT approved for
use in a wet location.
ANS THHN
conductors with THHN insulation are approved for use in dry and damp
locations only and conductors with THWN, THHW, and THW insulation
are recognized for use in dry and wet locations.
2.Given; A one-family dwelling unit with a demand load of 200 amperes is
sup- plied with a 120/240 volt, single-phase, electrical system from the local
utility company. What is the MINIMUM size aluminum THW conductors
required for use as service-entrance conductors for this residence?
ANS 4/0 AWG
one-family dwelling 120/240 volt, single-phase, service-entrance
conductors to be sized at an ampacity of not less than 83% of the
service rating. Therefore, 200 amperes x 83% = 166 amperes; size 4/0
AWG THW aluminum conductors with an allowable ampacity of 180
amperes should be selected for this dwelling.
3.Where a 150 kVA, single-phase transformer having a secondary voltage
,of 120/240 is installed at a multi-family dwelling, the full-load current rating,
in amperes, of the secondary is .
ANS 625 amperes
To find the full-load current rating of the single-phase transformer
apply the sin- gle-phase current formula as shownI = (150 kVA x 1000)
/ 240 volts = 15,000/240
= 625 amperes
4.Which one of the following listed circuit breakers is NOT a standard
ampere rating?
ANS 75 amperes
the standard ampere ratings for fuses and circuit breakers. A circuit
breaker with an ampere rating of 75 amperes is not a standard ampere
rating.
5.The MINIMUM length of free conductor to be left at each junction box for
the purpose of splicing conductors, or making connections to illuminares
or devices shall be .
ANS 6 inches
free conductor is to be left at each junction box for splices or the
connection of luminaires or devices. The intent of this rule is to ensure
enough conductor slack for the terminal connections or splices to be
made easily.
, 6.In general, overhead service-drop conductors shall NOT be smaller than
.
ANS 8 AWG copper
overhead service-drop conductors to be not smaller than 8 AWG copper
or 6 AWG aluminum or copper-clad aluminum. Do not get service-drop
conductors, the
overhead conductors between the utility electric supply system and the
service point, confused with the service-entrance conductors, the
conductors from the service point from the utility company to the
service disconnecting means.
7.When a galvanized eye-bolt is to be used as the point of attachment for an
electrical service, the NEC requires the eye-bolt to be installed NOT less
than
above finished grade.
ANS 10 ft.
provide adequate vertical clearance of the conductors and prevent
physical damage to the conductors and prevent persons from making
accidental contact with the conductors which may create a shock
hazard or electrocution. In no case shall the point of attachment of the
service-drop conductors to be less than 10 ft. above finished grade.
Questions and Answers
1.Conductors with marked on the insulation are NOT approved for
use in a wet location.
ANS THHN
conductors with THHN insulation are approved for use in dry and damp
locations only and conductors with THWN, THHW, and THW insulation
are recognized for use in dry and wet locations.
2.Given; A one-family dwelling unit with a demand load of 200 amperes is
sup- plied with a 120/240 volt, single-phase, electrical system from the local
utility company. What is the MINIMUM size aluminum THW conductors
required for use as service-entrance conductors for this residence?
ANS 4/0 AWG
one-family dwelling 120/240 volt, single-phase, service-entrance
conductors to be sized at an ampacity of not less than 83% of the
service rating. Therefore, 200 amperes x 83% = 166 amperes; size 4/0
AWG THW aluminum conductors with an allowable ampacity of 180
amperes should be selected for this dwelling.
3.Where a 150 kVA, single-phase transformer having a secondary voltage
,of 120/240 is installed at a multi-family dwelling, the full-load current rating,
in amperes, of the secondary is .
ANS 625 amperes
To find the full-load current rating of the single-phase transformer
apply the sin- gle-phase current formula as shownI = (150 kVA x 1000)
/ 240 volts = 15,000/240
= 625 amperes
4.Which one of the following listed circuit breakers is NOT a standard
ampere rating?
ANS 75 amperes
the standard ampere ratings for fuses and circuit breakers. A circuit
breaker with an ampere rating of 75 amperes is not a standard ampere
rating.
5.The MINIMUM length of free conductor to be left at each junction box for
the purpose of splicing conductors, or making connections to illuminares
or devices shall be .
ANS 6 inches
free conductor is to be left at each junction box for splices or the
connection of luminaires or devices. The intent of this rule is to ensure
enough conductor slack for the terminal connections or splices to be
made easily.
, 6.In general, overhead service-drop conductors shall NOT be smaller than
.
ANS 8 AWG copper
overhead service-drop conductors to be not smaller than 8 AWG copper
or 6 AWG aluminum or copper-clad aluminum. Do not get service-drop
conductors, the
overhead conductors between the utility electric supply system and the
service point, confused with the service-entrance conductors, the
conductors from the service point from the utility company to the
service disconnecting means.
7.When a galvanized eye-bolt is to be used as the point of attachment for an
electrical service, the NEC requires the eye-bolt to be installed NOT less
than
above finished grade.
ANS 10 ft.
provide adequate vertical clearance of the conductors and prevent
physical damage to the conductors and prevent persons from making
accidental contact with the conductors which may create a shock
hazard or electrocution. In no case shall the point of attachment of the
service-drop conductors to be less than 10 ft. above finished grade.
