Unit 2: Branch Circuits

Question 1

In general, for other than dwelling units, all 15- and 20-ampere, 125-volt, single-phase receptacles installed on rooftops must be provided with:

I. GFCI protection
II. AFCI protection

Answer 1

I only

Question 2

Fill in the blank:

Where the motor controller also serves as a disconnecting means, it shall open all _____ conductors to the motor.

Answer 2

ungrounded

Question 3

Fill in the blank:

Before demand factors are taken into consideration for commercial occupancies, general-purpose 125-volt, single-phase 15- or 20-ampere rated receptacles are to be computed at not less than _____ per duplex or single receptacle outlet mounted on one yoke.

Answer 3

180 VA

Question 4

Fill in the blank:

Conductors with ____\__ insulation have a greater ampacity when used in a dry location compared to when used in a wet location.

Answer 4

THHW

Question 5

Fill in the blank:

Where a submersible pump is used in a metal well casing, the well casing shall be _____ the pump circuit equipment grounding conductor.

Answer 5

connected to

Question 6

Fill in the blank:

In a health care facility, low voltage electrical equipment that is likely to become energized that is frequently in contact with the bodies of patients, shall operate on a voltage of _____ or less if the equipment is not approved as intrinsically safe, double insulated or moisture resistant.

Answer 6

10 volts

Question 7

Fill in the blank:

When ambient temperature is not a factor, a size 8 AWG single-insulated copper conductor with type FEPB insulation, installed in free air, has an ampacity of _____.

Answer 7

80 amperes

Question 8

Fill in the blank:

For the purpose of determining conductor fill in a device box, a three-way toggle switch is counted as equal to _____ conductor(s), based on the largest conductor connected to the switch.

Answer 8

two

Question 9

Fill in the blank:

When determining the required ampacity of the branch circuit conductors to supply a 3-phase, continuous duty ac motor, current values given on _____ shall be used.

Answer 9

Table 430.250 of the NEC

Question 10

When calculating the total load for a building or structure, what is the minimum computed branch circuit load, in volt-amps, permitted by the NEC for a branch circuit serving an exterior continuous-duty electric sign?

Answer 10

1,500 volt-amps

1,200 VA x 125% = 1,500 VA

Question 11

Determine the maximum number of size 1 AWG XHHW copper conductors permitted in a trade size 3 in. Schedule 40 rigid PVC conduit more than 24 inches long.

Answer 11

19

Question 12

Fill in the blank:

Infrared commercial and industrial heating appliances shall have overcurrent protection not exceeding _____.

Answer 12

50 amperes

Question 13

Fill in the blank:

Class _____ hazardous locations are those in which flammable liquidproduced vapors, or combustible liquid-produced vapors are or may be present in the air in quantities sufficient to produce explosive or ignitable mixtures.

Answer 13

I

Question 14

Fill in the blank:

In indoor areas where walls are frequently washed, such as laundries or car washes, metallic conduit and metallic panelboards shall be mounted with a _____ space between the wall and conduit or panelboard when the equipment is installed exposed.

Answer 14

1/4 in.

Question 15

Fill in the blank:

A branch circuit served by size 12 AWG conductors is a _____ rated branch circuit when protected by a 15-ampere circuit breaker.

Answer 15

15 ampere

Question 16

What is the maximum overcurrent protection allowed for the protection of resistance-type fixed electric space heating equipment?

Answer 16

60 amperes

Question 17

Fill in the blank:

Information technology equipment shall be permitted to be connected to a branch circuit by a listed power-supply cord having a length not to exceed _____.

Answer 17

15 feet

Question 18

Fill in the blank:

Type MI cable shall be supported and secured by straps, staples or similar fittings at intervals not exceeding _____.

Answer 18

6 feet

Question 19

Fill in the blank:

General use snap switches supplying inductive loads shall be loaded to no more than _____ of the ampere rating of the switch at the applied voltage.

Answer 19

50 percent

Question 20

Fill in the blank:

Direct-buried conductors emerging from grade shall be protected by raceways or covers up to a point of at least _____ above finished grade.

Answer 20

8 feet

Question 21

What is the required size wire-type copper equipment grounding conductor for a 50-ampere rated branch circuit where the conductors are installed in PVC conduit?

Answer 21

10 AWG

Question 22

Fill in the blank:

Disregarding exceptions, all 3-phase, 4-wire, 480Y/277-volt, electrical services, require ground-fault protection for each service disconnecting means, when rated for at least _____ or more.

Answer 22

1,000 amperes

Question 23

Determine the conductor ampacity given the following related information:
* conductors are size 500 kcmil copper
* conductor insulation is THWN
* eight (8) current-carrying conductors are in the raceway
* ambient temperature is 125 deg. F
* conduit length is 50 feet
* installation is a wet location

Answer 23

178.2 amperes

Size 500 KCMIL THWN copper ampacity before derating = 380 amperes

380 amperes x .67 (temp. correction) x .7 (adjustment factor) = 178.22 amperes

Question 24

Fill in the blank:

When connecting to luminaires, trade size 3/8 in. flexible metal conduit (FMC) is permitted to enclose tap conductors, provided the length of the FMC does not exceed _____.

Answer 24

6 feet

Question 25

# Fill in the blank: Where a trade size 1/2 in. rigid metal conduit (RMC) is installed in a Class I location and a 1/2 in. conduit completed seal is required, the minimum thickness of the sealing compound shall not be less than \_\_\_\_\_.

Answer 25

5/8 in.