CFESA Electrical UPDATED ACTUAL
Exam Questions and CORRECT Answers
What do the following prefixes mean? Micro,Kilo,Mega,Milli - CORRECT ANSWER -
1/1,000,000, 1000, 1,000,000, 1/1000
If you know the wattage and voltage, how do you determine the current? - CORRECT
ANSWER - Divide the wattage by the voltage
If you know the voltage and current how do you determine the wattage? - CORRECT
ANSWER - Multiply voltage times current
If a circuit is supplied with 100 volts and the total resistance of the circuit is 200 ohms, how
much current will the circuit draw? - CORRECT ANSWER - .5 amps
If a piece of equipment is supplied 208 volts and the amp meter clamped to the hot line reads 20
amps, what is the wattage of the load? - CORRECT ANSWER - 4160 Watts
How much voltage is in one hot line? - CORRECT ANSWER - None
What happens to current in a parallel circuit? - CORRECT ANSWER - It divides across
resistances
what happens to voltage across the loads in a parallel circuit? - CORRECT ANSWER -
stays the same
what happens to the voltage across the loads in a series circuit? - CORRECT ANSWER -
it divides across the resistances
,what happens to the current in a series circuit? - CORRECT ANSWER - It stays the same
everywhere
in a parallel circuit the total resistance of the circuit will always be less than what resistance? -
CORRECT ANSWER - the smallest resistance
how do you find the total resistance of a series circuit? - CORRECT ANSWER - add the
resistances together
how do you find the total resistance of a parallel circuit? - CORRECT ANSWER - 1/RT =
1/R1 + 1/R2 + 1/R3 ...
If a circuit is wired parallel, and the supply voltage is 120 volts, each load must be rated at what
voltage? - CORRECT ANSWER - 120 volts
if a circuit has two elements wired in series, and each is rated at 120 volts, what voltage must be
supplied to the circuit in order for the elements to heat at full power? - CORRECT
ANSWER - 240 volts
What is the advantage of using higher voltages? - CORRECT ANSWER - Lower Current
and wire size
Is there a negative and positive line in AC power supplies? - CORRECT ANSWER - No
What is the voltage between two hot lines in a 230-volt system? - CORRECT ANSWER -
230V
What is the voltage between two hot lines in a 208-volt system? - CORRECT ANSWER -
208V
,What is the voltage between a hot line and a neutral in a 230-volt single phase supply? -
CORRECT ANSWER - 115V
What is the voltage between a hot line and a neutral in a 208-volt single phase supply? -
CORRECT ANSWER - 120V
What is the accepted maximum voltage difference between the name plate voltage and the
supplied voltage? - CORRECT ANSWER - + or - 10%
What is the voltage between any two hot lines of a 230 volt delta power supply? - CORRECT
ANSWER - 230V
what is the voltage between a hot line and ground on a 240 volt delta power supply - CORRECT
ANSWER - No usable voltage
what is the voltage between any two hot lines of a 230 volt grounded delta power supply -
CORRECT ANSWER - 230V
draw a diagram of a 230 volt grounded delta power supply. label all of the voltages and the wild
leg - CORRECT ANSWER -
what is the wild leg? - CORRECT ANSWER - leg with higher than 120v to ground or
neutral
what danger is the wild leg? - CORRECT ANSWER - high voltage that will damage 120v
component in the circuit
what is the voltage between either of the non wild leg hot lines and neutral in a 230 volt
grounded delta system? - CORRECT ANSWER - 115v
, how do you determine which hot line is the wild leg in a 250 volt grounded delta power supply?
- CORRECT ANSWER - the one that does not measure 120 volts to neutral or ground
what danger is there when replacing a three phase circuit breaker in a 230 volt grounded delta
power supply? - CORRECT ANSWER - crossing the hot lines and supplying the wild leg
to the wrong terminal in the unit.
Why is a "WYE" power supply so versatile - CORRECT ANSWER - can get 120v and
208v as well as single and three phase
What is the voltage between any two hot lines in a 208 volt WYE power supply? - CORRECT
ANSWER - 208v
What is the voltage between any hot line and neutral or ground in a 208 volt WYE power
supply? - CORRECT ANSWER - 120v
What is the voltage from any hot line to ground or neutral, on a 480 volt WYE power supply? -
CORRECT ANSWER - 277v
if you had a commercial building and you had a three phase supply to your building how many
different incoming power supplies would you need if the incoming three phase supply was three
phase delta? - CORRECT ANSWER -2
if you had a commercial building and you had a three phase supply to your building, how many
different incoming power supplies would you need if the incoming three phase supply was three
phase grounded delta? - CORRECT ANSWER -1
if you had a commercial building and you had a three phase supply to your building how many
different incoming power supplies would you need if the incoming three phase supply was three
phase WYE 208v? - CORRECT ANSWER -1
Exam Questions and CORRECT Answers
What do the following prefixes mean? Micro,Kilo,Mega,Milli - CORRECT ANSWER -
1/1,000,000, 1000, 1,000,000, 1/1000
If you know the wattage and voltage, how do you determine the current? - CORRECT
ANSWER - Divide the wattage by the voltage
If you know the voltage and current how do you determine the wattage? - CORRECT
ANSWER - Multiply voltage times current
If a circuit is supplied with 100 volts and the total resistance of the circuit is 200 ohms, how
much current will the circuit draw? - CORRECT ANSWER - .5 amps
If a piece of equipment is supplied 208 volts and the amp meter clamped to the hot line reads 20
amps, what is the wattage of the load? - CORRECT ANSWER - 4160 Watts
How much voltage is in one hot line? - CORRECT ANSWER - None
What happens to current in a parallel circuit? - CORRECT ANSWER - It divides across
resistances
what happens to voltage across the loads in a parallel circuit? - CORRECT ANSWER -
stays the same
what happens to the voltage across the loads in a series circuit? - CORRECT ANSWER -
it divides across the resistances
,what happens to the current in a series circuit? - CORRECT ANSWER - It stays the same
everywhere
in a parallel circuit the total resistance of the circuit will always be less than what resistance? -
CORRECT ANSWER - the smallest resistance
how do you find the total resistance of a series circuit? - CORRECT ANSWER - add the
resistances together
how do you find the total resistance of a parallel circuit? - CORRECT ANSWER - 1/RT =
1/R1 + 1/R2 + 1/R3 ...
If a circuit is wired parallel, and the supply voltage is 120 volts, each load must be rated at what
voltage? - CORRECT ANSWER - 120 volts
if a circuit has two elements wired in series, and each is rated at 120 volts, what voltage must be
supplied to the circuit in order for the elements to heat at full power? - CORRECT
ANSWER - 240 volts
What is the advantage of using higher voltages? - CORRECT ANSWER - Lower Current
and wire size
Is there a negative and positive line in AC power supplies? - CORRECT ANSWER - No
What is the voltage between two hot lines in a 230-volt system? - CORRECT ANSWER -
230V
What is the voltage between two hot lines in a 208-volt system? - CORRECT ANSWER -
208V
,What is the voltage between a hot line and a neutral in a 230-volt single phase supply? -
CORRECT ANSWER - 115V
What is the voltage between a hot line and a neutral in a 208-volt single phase supply? -
CORRECT ANSWER - 120V
What is the accepted maximum voltage difference between the name plate voltage and the
supplied voltage? - CORRECT ANSWER - + or - 10%
What is the voltage between any two hot lines of a 230 volt delta power supply? - CORRECT
ANSWER - 230V
what is the voltage between a hot line and ground on a 240 volt delta power supply - CORRECT
ANSWER - No usable voltage
what is the voltage between any two hot lines of a 230 volt grounded delta power supply -
CORRECT ANSWER - 230V
draw a diagram of a 230 volt grounded delta power supply. label all of the voltages and the wild
leg - CORRECT ANSWER -
what is the wild leg? - CORRECT ANSWER - leg with higher than 120v to ground or
neutral
what danger is the wild leg? - CORRECT ANSWER - high voltage that will damage 120v
component in the circuit
what is the voltage between either of the non wild leg hot lines and neutral in a 230 volt
grounded delta system? - CORRECT ANSWER - 115v
, how do you determine which hot line is the wild leg in a 250 volt grounded delta power supply?
- CORRECT ANSWER - the one that does not measure 120 volts to neutral or ground
what danger is there when replacing a three phase circuit breaker in a 230 volt grounded delta
power supply? - CORRECT ANSWER - crossing the hot lines and supplying the wild leg
to the wrong terminal in the unit.
Why is a "WYE" power supply so versatile - CORRECT ANSWER - can get 120v and
208v as well as single and three phase
What is the voltage between any two hot lines in a 208 volt WYE power supply? - CORRECT
ANSWER - 208v
What is the voltage between any hot line and neutral or ground in a 208 volt WYE power
supply? - CORRECT ANSWER - 120v
What is the voltage from any hot line to ground or neutral, on a 480 volt WYE power supply? -
CORRECT ANSWER - 277v
if you had a commercial building and you had a three phase supply to your building how many
different incoming power supplies would you need if the incoming three phase supply was three
phase delta? - CORRECT ANSWER -2
if you had a commercial building and you had a three phase supply to your building, how many
different incoming power supplies would you need if the incoming three phase supply was three
phase grounded delta? - CORRECT ANSWER -1
if you had a commercial building and you had a three phase supply to your building how many
different incoming power supplies would you need if the incoming three phase supply was three
phase WYE 208v? - CORRECT ANSWER -1
