Deck 7: Introduction to Residential Service Entrances

Question 1

The point of connection between the wiring of the electric utility and the house wiring is called the __________.

A) service drop
B) service lateral
C) service point
D) service conductors

Answer 1

C

Question 2

If a concrete encased electrode is used, the end of the 4 AWG copper conductor or the end of the re-bar (whichever is used) can be extended from its location in the concrete to an accessible location above the concrete.

Answer 2

True

Question 3

Grounding electrode conductors do not need to comply with the Section 300.5 rules for burial depths when being installed underground.

Answer 3

True

Question 4

If a single grounding electrode that is a rod, pipe or plate does not have resistance to earth of 25 ohms or less, an additional electrode must be installed.

Question 5

The enclosure housing a temporary service entrance disconnecting means must be dust-tight.

Question 6

The NEC requires a vertical clearance of at least __________ feet above public streets, alleys, roads, and parking areas subject to truck traffic.

A) 10
B) 12
C) 15
D) 18

Question 7

The NEC requires a minimum clearance of __________ feet above residential property and driveways where the voltage to ground does not exceed 300 volts.

A) 18
B) 10
C) 15
D) None of the above

Question 8

A coupling connecting two conduits together for a service mast can be located above the last point of securement to the house.

Question 9

Overhead service conductors are permitted to be attached to trees for support.

Question 10

Direct buried conductors emerging from the ground must be protected to a point at least __________ feet above finished grade.

A) 1.5
B) 2.5
C) 5
D) 8

Question 11

A metal underground water pipe in contact with the earth for 10 feet or more is permitted to be the only grounding electrode needed to meet NEC requirements.

Question 12

Service conductors are considered outside of a house when they are installed under at least 2 inches (50 mm) of concrete beneath a house; where installed in a conduit under at least 18 inches (450 mm) of earth beneath a house; or where they are installed in rigid metal conduit (RMC) or intermediate metal conduit (IMC) when used as a service mast that extends through an eave.

Question 13

The NEC requires a clearance of at least __________ feet above final grade for service conductors where they are connected to the building, above sidewalks and other areas accessible to pedestrians.

A) 18
B) 12
C) 10
D) 8

Question 14

When a warning ribbon is required to mark the location of buried underground service conductors, it must be placed at least __________ inches above the buried conductors.

A) 8
B) 12
C) 18
D) 24

Question 15

Outdoor light fixtures are permitted to be attached to trees.

Question 16

When installing service drop conductors above a residential roof, conductors must have a vertical clearance of at least __________. (General Rule)

A) 3 feet
B) 5 feet
C) 8 feet
D) 10 feet

Question 17

__________ is a general term used for material, fittings, devices, appliances, lighting fixtures, apparatus, machinery, and other parts used in connection with an electrical installation.

A) Circuit
B) Equipment
C) Enclosure
D) Electrode

Question 18

Who is the final authority for determining the required vertical clearances for service conductors?

A) Underwriters Laboratories
B) National Electrical Code
C) National Electrical Manufacturers Association
D) Utility Company

Question 19

The overhead service conductors from the last pole to the point connecting them to the service entrance conductors at the building are called __________ conductors.

A) service drop
B) riser
C) service lateral
D) None of the above

Question 20

Underground service conductors installed as a cable assembly are required to be buried at least __________ feet by the NEC.

A) 1
B) 2
C) 3
D) 4

Question 21

The wiring methods allowed for underground service entrance installations are listed in Section 230.30(B). They include rigid metal conduit (RMC), intermediate metal conduit (IMC), __________, and USE conductors or cables.

A) rigid PVC conduit (PVC)
B) Type NM cable
C) Type AC cable
D) electrical metallic tubing (EMT)

Question 22

The type of cable normally used as the service drop for a residential service entrance is called __________.

A) quadplex cable
B) Romex
C) triplex cable
D) UF cable

Question 23

When a ground ring is used as a grounding electrode, it must be at least a 2 AWG copper conductor at least __________ feet long.

A) 15
B) 20
C) 30
D) 50

Question 24

According to NEC Table 250.66, the minimum size copper grounding electrode conductor for a service entrance installed with 4/0 copper conductors is__________.

A) 8 AWG
B) 6 AWG
C) 4 AWG
D) 2 AWG

Question 25

When a metal underground water pipe is used as a grounding electrode, it must be in contact with the earth for at least __________ feet.

A) 5
B) 8
C) 10
D) 12

Question 26

When bonding together the noncurrent carrying metal parts of a service entrance, which of the following methods may be used?

A) exothermic welding
B) listed pressure connectors
C) listed clamps
D) all of the above

Question 27

A system or circuit conductor that is intentionally grounded is called a(n) _______________ conductor.

Question 28

Where service entrance conductors extend from the weatherhead, a _______________ is required to keep water from entering the weatherhead and getting into the meter enclosure.

Question 29

Where more than one ground rod, pipe, or plate is used, the grounding electrodes must be at least __________ feet apart.

A) 4
B) 8
C) 10
D) None of the above

Question 30

A(n) __________ is the conductor connected to the neutral point of a system and is intended to carry current under normal conditions.

A) grounding conductor
B) ungrounded conductor
C) service conductor
D) neutral conductor

Question 31

120/240-volt overhead service conductors must maintain a vertical clearance of at least __________ feet above the back yard of a house.

A) 10
B) 12
C) 15
D) 18

Question 32

The __________ is the conductor used to connect the grounding electrode to a system conductor or equipment.

A) grounding electrode conductor
B) grounding conductor
C) neutral conductor
D) service conductor

Question 33

One set of service entrance conductors is permitted to supply __________ service disconnecting means instead of a single main disconnect.

A) 2 to 4
B) 2 to 6
C) 3 to 6
D) 3 to 5

Question 34

_______________ is the term for being connected together to establish electrical continuity and conductivity.

Question 35

Copper coated steel ground rods must be listed and be at least __________ in diameter.

A) 1/2"
B) 5/8"
C) 3/4"
D) 1"

Question 36

If a service entrance is rated at 200 amps, the service entrance conductor size would be a minimum of 2/0 copper or 4/0 aluminum. According to Table 250.102(C)(1) the minimum bonding jumper size would be _____ AWG.

A) 1
B) 2
C) 3
D) 4

Question 37

Section 250.4(A) explains that electrical systems are grounded to limit the voltage imposed by lightning, line surges, or unintentional contact with higher-voltage lines and to ________ the voltage to earth during normal operation.

A) alter
B) stop
C) stabilize
D) permit

Question 38

A(n) __________ is a conducting object through which a direct connection to the earth is established.

A) bond wire
B) grounding electrode
C) main bonding jumper
D) grounded conductor

Question 39

Service entrance cables must be supported by straps or staples within __________ inches of any electrical enclosure or weatherhead and at intervals not exceeding __________ inches.

A) 8, 24
B) 12, 24
C) 8, 30
D) 12, 30

Question 40

Ground rods must be at least ________ feet long.

A) 6
B) 8
C) 10
D) 12

Question 41

Article _______________ of the NEC covers the grounding and bonding requirements for residential services.

Question 42

Explain why the NEC and local utility companies require the service entrance disconnecting means, if located inside a house, to be installed as close as possible to where the service conductors enter the house.

Question 43

A length of raceway that extends up a utility pole and encloses the service entrance conductors in an underground service is called a(n) _______________.

Question 44

A piece of electrical equipment used by the utility company to step down the high voltage of the utility system to the 120/240 volts required for a residential electrical system is called a(n) _______________.

Question 45

Explain why a seal is required anytime a raceway containing electrical conductors is installed from a cold area to a warm area.

Question 46

The _______________ conductor of an AC service is connected to a grounding electrode system to limit the voltage to ground from lightning, line surges, and unintentional high voltage crossovers, and to stabilize the voltage to ground during normal operation.

Question 47

A transformer designed to be mounted directly on a foundation at ground level is called a(n) ____________________________.

Question 48

A ground rod cannot be driven completely into the ground because of large rocks in the soil. Explain what options you have to meet NEC requirements.