Code, Standards, and Practices 1, Based on the 2020 NEC Online Materials: Lesson 6 Understanding Conductor Insulation and NEC Specifications

Question 1

A conductor having no covering or electrical insulation whatsoever is defined in the NEC as a(n) ? conductor.
Select one:

a.
aluminum

b.
bare

c.
copper

d.
grounded

Answer 1

bare

Question 2

A conductor meeting the definition of a covered conductor is not considered an insulated conductor.
Select one:
True
False

Answer 2

True

Question 3

In order for a material to be recognized as an insulation, it must ? .
Select one:

a.
be made of material recognized as insulation by the Code

b.
have the proper thickness as specified by the Code

c.
both a. and b.

d.
neither a. nor b.

Answer 3

both a. and b.

Note: See Table 310.4(A) Insulation column and Thickness of Insulation columns.

Question 4

Insulated conductors installed in a conduit, in a concrete slab, in contact with the earth, would be considered to be installed in a ? .
Select one:

a.
damp location

b.
dry location

c.
semi-dry location

d.
wet location

Answer 4

wet location

Question 5

Electrical conductors installed in the office area of a building would be considered located in a ? .
Select one:

a.
damp location

b.
dry location

c.
hazardous location

d.
wet location

Answer 5

dry location

Question 6

Electrical conductors installed in a cold storage warehouse could be considered located in a ? .
Select one:

a.
damp location

b.
dry location

c.
semi-dry location

d.
wet location

Answer 6

damp location

Question 7

Electrical conductors directly buried in the earth would be considered located in ? .
Select one:

a.
damp location

b.
dry location

c.
semi-dry location

d.
wet location

Answer 7

wet location

Question 8

One of the primary functions of insulation is to ? .
Select one:

a.
contain the heat

b.
contain the voltage

c.
make the conductors easier to pull

d.
protect the resistance of the conductor

Answer 8

contain the voltage

Question 9

High heat will have a deteriorating effect on a conductor’s insulation.
Select one:
True
False

Answer 9

True

Question 10

Which of the following is/are characteristic(s) of good insulation?
Select one:

a.
Ability to withstand heat

b.
Long life

c.
Mechanical flexibility

d.
Resistance to moisture

e.
All of the above

Answer 10

All of the above

Question 11

Informational note guidance advises that thermoplastic insulation may stiffen at temperatures lower than 14°F.
Select one:
True
False

Answer 11

True

Question 12

Which of the listed heat sources does not normally contribute to the deteriorating of the conductor’s insulation?
Select one:

a.
Adjacent load-carrying conductors

b.
Ambient temperature

c.
Heat from containment

d.
Heat generated by current flow

e.
All of the above contribute to the deteriorating of the conductor insulation

Answer 12

All of the above contribute to the deteriorating of the conductor insulation

Question 13

When current flows through a conductor, ? .
Select one:

a.
heat will be generated within the conductor

b.
the conductor will become hardened

c.
the conductor will increase in size

d.
the insulation will cool the conductor

Answer 13

heat will be generated within the conductor

Question 14

NEC Table 310.4(A) and the Reference may be used for the following question.

Which statement(s) is/are true concerning the conductor insulation?

Select one:

a.
The insulation will have a temperature rating.

b.
The insulation will have a voltage rating.

c.
Both a. and b.

d.
Neither a. nor b.

Answer 14

Both a. and b.

Question 15

NEC Table 310.4(A) and the Reference may be used for the following question.

NEC Table 310.4(A) covers conductor ? and ? rated 600 volts.

Select one:

a.
applications / insulations

b.
construction / application

c.
construction / insulations

d.
none of the above

Answer 15

applications / insulations

Question 16

NEC Table 310.4(A) and the Reference may be used for the following question.

The Code trade name for type THHN insulation is heat-resistant thermoplastic.

Select one:
True
False

Answer 16

True

Question 17

Use NEC Table 310.4(A) and the Reference for the following question.

Match the following letter to the insulation characteristic or material for which it stands.

H is heat resistant
R is rubber covering
T is thermoplastic
X is cross-link poly

Question 18

NEC Table 310.4(A) and the Reference may be used for the following question.

Which statement(s) is/are true when applied to conductor coverings?

Select one:

a.
Conductor covering materials are considered to have the same insulating properties as conductor insulating materials.

b.
When the letter “L” is used, it indicates a linen covering over the insulation.

c.
Both a. and b.

d.
Neither a. nor b.

Answer 18

Neither a. nor b.

Question 19

NEC Table 310.4(A) and the Reference may be used for the following question.

Type “MI” insulation is identified as ? .

Select one:

a.
magnetic insulation

b.
metallic insulation

c.
mineral insulation

d.
none of the above

Answer 19

mineral insulation

Question 20

NEC Table 310.4(A) and the Reference may be used for the following question.

The Centigrade and Fahrenheit temperature ratings of THW conductor insulations used in a dry location are ? .

Select one:

a.
30°C (86°F)

b.
60°C (140°F)

c.
75°C (167°F)

d.
90°C (194°F)

Answer 20

75°C (167°F)

Question 21

NEC Table 310.4(A) and the Reference may be used for the following question.

The Centigrade and Fahrenheit temperature rating of THHW conductor insulation used in a dry location is ? .

Select one:

a.
30°C (86°F)

b.
60°C (140°F)

c.
75°C (167°F)

d.
90°C (194°F)

Answer 21

90°C (194°F)

Question 22

NEC Table 310.4(A) and the Reference may be used for the following question.

The maximum operating temperature of type USE insulation is ? .

Select one:

a.
30°C (86°F)

b.
60°C (140°F)

c.
75°C (167°F)

d.
90°C (194°F)

Answer 22

75°C (167°F)

Question 23

NEC Table 310.4(A) and the Reference may be used for the following question.

Match each of the letters of Type THWN insulation with its insulation material or characteristic.

T is thermoplastic
H is heat resistant
W is wet locations
N is nylon covering

Question 24

NEC Table 310.4(A) and the Reference may be used for the following question.

The thickness of the insulation on a conductor is measured in ? .

Select one:

a.
centimeters

b.
inches

c.
meters

d.
mils

Answer 24

mils

Question 25

When conductors are to be spliced or terminated in a junction box, Section 300.14 generally requires at least ? of free conductor to be left available for splicing or terminating.

Select one:

a.
4”

b.
6”

c.
8”

d.
10”

Answer 25

6”

Question 26

Which statement(s) is/are true when applying Section 310.8 for marking electrical conductors?
Select one:

a.
The maximum rated voltage for which the conductor is listed shall be durably marked on the surface of the conductor.

b.
The size of the conductor shall be durably marked on the surface of the conductor.

c.
Both a. and b.

d.
Neither a. nor b.

Answer 26

Both a. and b.