THE QUIZ – Test your electrician’s skills
It’s always a good idea to put the sparks into your memory and shed light on things you have learned years ago. Whether you are a rookie in a field of electrical engineering or a professional electrical engineer or electrician, try to complete this quiz without peeking on answers at the bottom of this article.
In most cases the test for the Master electrician’s exam has 30+ questions, lasts long and includes advanced electrical fundamentals and formulas. This quiz should be a piece of cake for you :)
Ok, let’s take a quiz:
Two resistors connected in a series across a 120 volt power source, where the first has a resistance of 28 ohms and the second has a resistance of 7 ohms, will generate a voltage drop across the first 28 ohms resistor of which of the following?
- 96 volts
- 60 volts
- 28 volts
- 120 volts
Based on the diagram below, a 4 ohms resistor, a 6 ohms resistor and a 12 ohms resistor are all connected in parallel. The total resistance in the circuit will be which of the following?
- 22 ohms
- 12 ohms
- 4 ohms
- 2 ohms
Electrical motors with the highest voltage rating are used for which of the following purpose(s)?
- To produce the maximum possible power from the motors
- To lower power consumption
- To reduce the size of the supply conductors required
- All of the above
Two incandescent 100 watt lamps operating for 8 hours at an average electrical energy cost of .12 cents per kilowatt hour will have a total energy cost equal to which of the following?
In a dry type transformer with a primary to secondary turns ratio of 4:1, if the primary is rated at 480 volts, then the secondary voltage will be which of the following?
- 1200 volts
- 480 volts
- 240 volts
- 120 volts
In a single phase, 3-wire 120/240 volt service entrance, where the hot conductor current is 28 amperes on the first leg and 42 amperes on the second leg, the current in the neutral will be which of the following?
- 14 amperes
- 56 amperes
- 84 amperes
- 126 amperes
Based on the diagram options below, which figure illustrates a 3-phase electrical system where one ungrounded conductor has a higher voltage to the ground than the other hot conductor?
The total resistance of the circuit conductors for a single-phase load with a copper conductor resistance of 0.510 ohms/k ft. that is 125 feet from the current supply is which of the following?
- 1.255 ohms
- 0.5100 ohms
- 0.2550 ohms
- 0.1275 ohms
If the diameter of a solid copper conductor is 0.125 inches, then the area of the conductor is equal to which of the following?
- 15,625 cmil
- 12,265 cmil
- 31,250 cmil
- 12,500 cmil
Which of the following conductors has the largest cross-sectional area in size?
- 14 AWG
- 4 AWG
- 6 AWG
- 12 AWG
According to the National Electric Code (NEC), which of the following must be true of wiring installed to meet the minimum Code requirements?
- It must provide the most convenient wiring applications
- It is safe and free from hazards
- It must allow for future expansion needs
- All of the above
When a 120/240 volt 100 amp panelboard with a removable front cover is installed in a single-family dwelling, and the opposite wall in front of the panelboard is concrete block construction, the minimum allowable distance between the front of the panelboard and the concrete block wall is which of the following?
- 18 inches
- 24 inches
- 36 inches
- 42 inches
The grounding electrode conductor connection to a driven ground rod shall be which of the following:
- Made with wire taps
- Not be required to be accessible
Low voltage equipment in a hospital that comes in frequent contact with people’s bodies must be which of the following:
- Able to operate at an electrical potential of 10 volts or less
- Approved as intrinsically safe
- Be moisture resistant
- All of the above
If a 240 volt conductor is 500 feet long and supplies a 10 amp load and the conductor has a resistance of 1.45 ohms per 1000 feet, then the total voltage drop in the conductor circuit conductors would be which of the following:
- 10 percent
- 7 percent
- 3 percent
- 1.45 percent
Grounding equipment with a 40 amp automatic overcurrent device in the circuit ahead of the equipment requires a minimum size copper equipment grounding conductor of which of the following sizes:
- None of the above
To confirm your electrician skills, your results should be the same as provided answers. NEC articles mentioned in answers you can observe in a free draft version of NEC 2014 //
- A | The voltage drop will be in the same proportion as each resistor in a series is to the total circuit resistance. 28 ohms is 80 percent of the total resistance (35 ohms, which is 28 + 7), so 80 percent of the voltage will be across the 28 ohms resistor. 0.8 × 120 volts = 96 volts
- D | 1/RT = 1/4 + 1/6 + 1/12 = 6/12; RT = 12/6 = 2 ohms
- C | Check the current of a particular motor at two different voltages in Table [430.148] or Table [430.150].
- D | 100 watts × 2 bulbs = 200 watts or 0.2 kW
0.2kW × 8 hours = 1.6 kilowatt hours
1.6 kWh × $0.12 = $0.19
- D | Primary voltage / Turns ratio = Secondary voltage;
480V / 4 = 120 volts SDF
- A | In a single-phase, 3-wire system, the current on the common neutral is the difference in the current flowing on the ungrounded legs.
42A − 28A = 14 amperes
- B | The question describes a 4-wire delta. The voltage from the neutral is connected to the center of one of the transformers at 208 volts to the phase at the top of the delta.
- D | There are two wires in the 125-foot run. 2 × 125 = 250, which is 25 percent of 1000 feet (k/ft.).
0.25 × 0.510 = 0.1275 ohms
- A | 0.125 inches = 125 mils
125 mils × 125 miles = 15,625 cmil
- B | Article 310, Table [310.16]
- B | Section [90.1(A)]
- C | Article 110, Table [110.26(A)(1)] column
- D | Section [250.68(A)] Exception
- D | Section [517.64(A)(1) & (2)]
- C | General Electrical Knowledge of E = I × R;
E = 10 × (500 / 1000) × 1.45 which equals 7.25 volts.
The percentage of the voltage drop is:
7.25 / 240 volts × 100 = 3 percent
- B | Table [250.122]
Reference // Electrician’s Exam Study Guide (Purchase at Amazon)