Ques ons and answers | Updated RATED A+ 2026
Conductors with _____ marked on the insula on are NOT approved for use in a wet loca on.
THHN
conductors with THHN insula on are approved for use in dry and damp loca ons only and
conductors with THWN, THHW, and THW insula on are recognized for use in dry and wet
loca ons.
Given: A one-family dwelling unit with a demand load of 200 amperes is supplied with a
120/240 volt, single-phase, electrical system from the local u lity 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 ra ng. 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.
Where a 150 kVA, single-phase transformer having a secondary voltage of 120/240 is installed
at a mul -family dwelling, the full-load current ra ng, in amperes, of the secondary is _____.
625 amperes
To find the full-load current ra ng of the single-phase transformer apply the single-phase
current formula as shown:I = (150 kVA x 1000) / 240 volts = 15,000/240 = 625 amperes
Which one of the following listed circuit breakers is NOT a standard ampere ra ng?
75 amperes
the standard ampere ra ngs for fuses and circuit breakers. A circuit breaker with an ampere
ra ng of 75 amperes is not a standard ampere ra ng.
The MINIMUM length of free conductor to be le> at each junc on box for the purpose of
splicing conductors, or making connec ons to illuminares or devices shall be _____ .
, 6 inches
free conductor is to be le> at each junc on box for splices or the connec on of luminaires or
devices. The intent of this rule is to ensure enough conductor slack for the terminal connec ons
or splices to be made easily.
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 overhead conductors between
the u lity electric supply system and the service point, confused with the service-entrance
conductors, the conductors from the service point from the u lity company to the service
disconnec ng means.
When a galvanized eye-bolt is to be used as the point of aAachment for an electrical service, the
NEC requires the eye-bolt to be installed NOT less than _____ above finished grade.
10 >.
provide adequate ver cal 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 electrocu on. In no case shall the point of aAachment of the service-
drop conductors to be less than 10 >. above finished grade.
Why is electrical con nuity required for metallic conduit?
To establish an effec ve ground-fault path and facilitate the opera on of the over-current
protec ve device.
Electrical con nuity is required for metallic conduit to establish an effec ve ground-fault path
and facilitate the opera on of the overcurrent protec ve device.
In dwelling units, receptacle outlets installed for countertop surfaces, must be located above,
but NOT more than _____ above the countertop or work surface.
20 inches
receptacle outlets installed for countertop or work surfaces in dwelling units may be located on
or above, but not more than 20 in. above the countertop or work surface. The intent of this rule
is to eliminate the use of unsightly extension cords (which reduces the amount of usable