Electrical Problem-Solving

When using a load of 20 amps and Type R copper wire, at what length of run does the conductor size first change from 12 to 10?

• 30

• 40

• 50

• 75

What is the minimum allowable size conductor for a 20-amp load using Type R aluminum?

• 10

• 8

• 6

• 4

Which type wire has the same minimum allowable size for conductors regardless of load?

• overhead in air

• Type R cable

• Type T cable

• Type TW cable

When using Type TW copper cable for a 100ˈ run, the minimum size conductor allowed is:

• 3 if carrying a 30 amp load

• 4 if carrying a 30 amp load

• 6 if carrying a 30 amp load

• 8 if carrying a 30 amp load

Mr. Blair has a 24′ x 40′ workshop.  He uses 8 ceiling fans rated at 50 watts and 8 four-bulb florescent lights.  If each fixture is equipped with 60-watt bulbs, how many watts of electricity will the fans and lights use during a 30-day period if they operate for 8 hours per day?

• 55,056

• 96,000

• 460,800

• 556,800

Mr. Cole’s shop has the same lights and fans as Mr. Blair’s shop in problem one.  However, he will also be using the electrical devices in the table below.  What will be the electrical bill for the shop for 30 days if electricity costs $.10619 per Kwh?  (Round the cost to the nearest cent.)

• $367.97

• $432.76

• $508.45

• $521.41

 The current rate for electricity is $.10619.  However, the rate will go up to $.10706 on July 1st.  Mr. Bowden has the same lights and equipment as Mr. Blair and Mr. Cole.  How much more than Mr. Cole will it cost for him to run his lights and equipment during the month of July than in the month of June, if they are run for the same time period that Mr. Blair and Mr. Cole run theirs?  (Round the cost to the nearest cent.)

• $2.69

• $3.54

• $3.77

• $4.05

Ms. Taylor has a 12″ Delta Table Saw wired on a 220-volt circuit.  The saw motor requires 4600 watts to start, but once started will run on 2000 watts.  How many more amperes of electricity are required to start the saw than to keep it running?  (Round the answer to the nearest hundredth.)

• 9.96

• 10.14

• 11.82

• 12.17

How many watts of electricity will a 5 – ampere motor running on 120 volts of electricity consume during a 30-day period if it operates for 6 hours per day?  W = VA

• 108,000

• 144,000

• 234,000

• 324,000