FREE IEC Electrical Calculations and Theory Questions and Answers

Question 1

What is the monthly expense for operating a 250-watt high-pressure sodium lamp? The electricity is priced at $0.15 per kWh, and the lamp will be in operation for 8 hours each day, with a billing month consisting of 30 days.

Accepted Answer

$9.00

Answer

$5.15

Answer

$10.50

Answer

$15.50

Question 2

What should be minimized to reduce conductor insulation damage and arcing damage to electrical equipment during a ground fault or short circuit?

Accepted Answer

The time duration of the fault should be minimized.

Answer

The mechanical interlock should be minimized.

Answer

The service point should be minimized.

Answer

The wattage should be minimized.

Question 3

How many feet should an extension ladder extend above the top of a building to ensure proper safety and be securely anchored?

Accepted Answer

3 feet

Answer

6 feet

Answer

10 feet

Answer

12 feet

Question 4

What term accurately describes a service lateral?

Accepted Answer

It is the underground feed.

Answer

It is a volt-ampere.

Answer

It is the overhead drop.

Answer

It is the service ground.

Question 5

What is the minimum quantity of receptacles needed in an unfinished basement?

Accepted Answer

1 receptacle

Answer

5 receptacles

Answer

8 receptacles

Answer

10 receptacles

Question 6

What reading will the voltmeter display if its leads are connected to T3 and T4?

Accepted Answer

120 volts

Answer

250 volts

Answer

220 volts

Answer

110 volts

Question 7

What is the smallest allowable AWG size for copper THHN/THWN conductors used in underground conductors for a 125-amp, 120/240-V, 3W residential service?

Accepted Answer

2 AWG copper

Answer

1 AWG copper

Answer

10 AWG copper

Answer

220 AWG copper

Question 8

How much is allowed for each branch circuit serving laundry receptacles when calculating residential service load?

Accepted Answer

1,500 volt-amperes

Answer

2,000 volt-amperes

Answer

2,500 volt-amperes

Answer

3,000 volt-amperes

Question 9

What voltage threshold, as per the Standard for Electrical Safety in the Workplace, necessitates de-energizing and locking out all electrical equipment before permitting work on or near it?

Accepted Answer

Over 50 volts

Answer

Over 110 volts

Answer

Over 120 volts

Answer

Over 150 volts

Question 10

How much current is flowing in the neutral conductor if circuits 7 and 9, sharing a neutral in a multi-wire branch circuit, draw 13 amps and 16 amps, respectively?

Accepted Answer

3 amps

Answer

2 amps

Answer

20 amps

Answer

50 amps