1. Conductors with marked on the insulation are NOT approved for use
in a wet location.: 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?: 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 .: 625 amperes
To find the full-load current rating of the single-phase transformer apply the sin-
gle-phase current formula as shown:I = (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?: 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 .: 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
.: 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
in a wet location.: 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?: 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 .: 625 amperes
To find the full-load current rating of the single-phase transformer apply the sin-
gle-phase current formula as shown:I = (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?: 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 .: 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
.: 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
