Licensed Electrical Contractor Code, Theory, and Calculations 2

Question 1

According to NEC Article 310, what is the ampacity of a 12 AWG copper conductor with THHN insulation installed in a conduit with an ambient temperature of 30°C?

Accepted Answer

30 A

Answer

20 A

Answer

25 A

Answer

15 A

Question 2

When applying the NEC demand factor for household electric dryers in a multifamily building with 20 dryers, what demand factor applies per Table 220.54?

Accepted Answer

35%

Answer

50%

Answer

70%

Answer

100%

Question 3

Kirchhoff's Voltage Law (KVL) states that the algebraic sum of all voltages around any closed loop equals:

Accepted Answer

Zero

Answer

The supply voltage

Answer

The total current times resistance

Answer

The maximum branch voltage

Question 4

A 240 V single-phase motor draws 18 A at a power factor of 0.85. What is the true (real) power consumed?

Accepted Answer

3,672 W

Answer

4,320 W

Answer

2,040 W

Answer

5,100 W

Question 5

Under NEC 230.70, the service disconnecting means must be located:

Accepted Answer

Inside the building as close as practicable to the point of service entry

Answer

At the utility transformer

Answer

On the exterior of the building only

Answer

In the main panelboard regardless of location

Question 6

In a parallel circuit, if one branch has a resistance of 10 Ω and another has 15 Ω, what is the total equivalent resistance?

Accepted Answer

6 Ω

Answer

25 Ω

Answer

12.5 Ω

Answer

7.5 Ω

Question 7

NEC Article 500 classifies hazardous locations. A Class I, Division 1 location is defined as one where:

Accepted Answer

Flammable gases or vapors are present under normal operating conditions

Answer

Combustible dust is present intermittently

Answer

Ignitable fibers are stored but not processed

Answer

Flammable liquids are present only during maintenance