CSLB C10 Electrical Contractor Practice
Examination Comprehensive Question Study Guide
Electrical Theory & Calculations
1. What is the minimum working clearance from an electrical panel under 600
V? ---ANSWER/✓ ---36"
2. Voltage drop in wire is a function of ---- - ✓✓ ANSWER---Wire gauge,
Length of wire, Current flow in the wire
3. A 12-volt direct current, 13-watt fluorescent light is controlled by a
photocell. The average daily on-time is 12 hours per day. How many watt-
hours are consumed by the light on an average day? ---- - ✓✓
ANSWER---156
4. 65 street lights are fed by a 2275-volt series circuit. What is the voltage
across each light? ---- - ✓✓ ANSWER---35 V
5. A 5 kW appliance is used for 5 hours. At $0.014 per kWh, the cost of
running the appliance is ---- - ✓✓ ANSWER---$0.35
6. For an electric appliance with a 17.5 A load, the overcurrent device must
not exceed ---- - ✓✓ ANSWER---25 amps
7. One million watts equals one ---- - ✓✓ ANSWER---Megawatt
, 8. What is the formula for calculating power in a DC circuit? ---- - ✓✓
ANSWER---P = I × V
9. How many milliamperes equal one ampere? ---- - ✓✓ ANSWER---1000
10.What is the total resistance of three 6-ohm resistors connected in series? --
-- - ✓✓ ANSWER---18 ohms
11.What is the total resistance of two 10-ohm resistors connected in parallel? -
--- - ✓✓ ANSWER---5 ohms
12.How many kilowatts equal 1500 watts? ---- - ✓✓ ANSWER---1.5 kW
13.What is the current draw of a 240-volt, 4800-watt electric heater? ---- -
✓✓ ANSWER---20 amps
14.What is the turns ratio of a transformer that steps down 480 volts to 120
volts? ---- - ✓✓ ANSWER---4:1
15.What is the voltage drop in a 100-foot run of 12 AWG copper wire carrying
20 amps? (Assume 2 ohms per 1000 feet) ---- - ✓✓ ANSWER---4 volts
Wiring Methods, Boxes & Conduit
16.Where may you use nonmetallic-sheathed cable? ---- - ✓✓ ANSWER--
-Inside floors and walls
17.What is the maximum permitted distance between convenience outlets in
kitchens? ---- - ✓✓ ANSWER---12'
18.What is the maximum distance to an outlet from any point along the wall
behind a kitchen counter? ---- - ✓✓ ANSWER---24"
Examination Comprehensive Question Study Guide
Electrical Theory & Calculations
1. What is the minimum working clearance from an electrical panel under 600
V? ---ANSWER/✓ ---36"
2. Voltage drop in wire is a function of ---- - ✓✓ ANSWER---Wire gauge,
Length of wire, Current flow in the wire
3. A 12-volt direct current, 13-watt fluorescent light is controlled by a
photocell. The average daily on-time is 12 hours per day. How many watt-
hours are consumed by the light on an average day? ---- - ✓✓
ANSWER---156
4. 65 street lights are fed by a 2275-volt series circuit. What is the voltage
across each light? ---- - ✓✓ ANSWER---35 V
5. A 5 kW appliance is used for 5 hours. At $0.014 per kWh, the cost of
running the appliance is ---- - ✓✓ ANSWER---$0.35
6. For an electric appliance with a 17.5 A load, the overcurrent device must
not exceed ---- - ✓✓ ANSWER---25 amps
7. One million watts equals one ---- - ✓✓ ANSWER---Megawatt
, 8. What is the formula for calculating power in a DC circuit? ---- - ✓✓
ANSWER---P = I × V
9. How many milliamperes equal one ampere? ---- - ✓✓ ANSWER---1000
10.What is the total resistance of three 6-ohm resistors connected in series? --
-- - ✓✓ ANSWER---18 ohms
11.What is the total resistance of two 10-ohm resistors connected in parallel? -
--- - ✓✓ ANSWER---5 ohms
12.How many kilowatts equal 1500 watts? ---- - ✓✓ ANSWER---1.5 kW
13.What is the current draw of a 240-volt, 4800-watt electric heater? ---- -
✓✓ ANSWER---20 amps
14.What is the turns ratio of a transformer that steps down 480 volts to 120
volts? ---- - ✓✓ ANSWER---4:1
15.What is the voltage drop in a 100-foot run of 12 AWG copper wire carrying
20 amps? (Assume 2 ohms per 1000 feet) ---- - ✓✓ ANSWER---4 volts
Wiring Methods, Boxes & Conduit
16.Where may you use nonmetallic-sheathed cable? ---- - ✓✓ ANSWER--
-Inside floors and walls
17.What is the maximum permitted distance between convenience outlets in
kitchens? ---- - ✓✓ ANSWER---12'
18.What is the maximum distance to an outlet from any point along the wall
behind a kitchen counter? ---- - ✓✓ ANSWER---24"
