CFESA ELECTRICAL EXAM QUESTIONS
AND CORRECT ANSWERS. VERIFIED
2025/2026.
What do the following prefixes mean? Micro,Kilo,Mega,Milli - ANS 1/1,000,000, 1000,
1,000,000, 1/1000
If you know the wattage and voltage, how do you determine the current? - ANS Divide the
wattage by the voltage
If you know the voltage and current how do you determine the wattage? - ANS 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? - ANS .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? - ANS 4160 Watts
How much voltage is in one hot line? - ANS None
What happens to current in a parallel circuit? - ANS It divides across resistances
1 @COPYRIGHT 2025/2026 ALLRIGHTS RESERVED.
,what happens to voltage across the loads in a parallel circuit? - ANS stays the same
what happens to the voltage across the loads in a series circuit? - ANS it divides across the
resistances
what happens to the current in a series circuit? - ANS It stays the same everywhere
in a parallel circuit the total resistance of the circuit will always be less than what resistance? -
ANS the smallest resistance
how do you find the total resistance of a series circuit? - ANS add the resistances together
how do you find the total resistance of a parallel circuit? - ANS 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? - ANS 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? - ANS 240 volts
What is the advantage of using higher voltages? - ANS Lower Current and wire size
Is there a negative and positive line in AC power supplies? - ANS No
What is the voltage between two hot lines in a 230-volt system? - ANS 230V
2 @COPYRIGHT 2025/2026 ALLRIGHTS RESERVED.
,What is the voltage between two hot lines in a 208-volt system? - ANS 208V
What is the voltage between a hot line and a neutral in a 230-volt single phase supply? -
ANS 115V
What is the voltage between a hot line and a neutral in a 208-volt single phase supply? -
ANS 120V
What is the accepted maximum voltage difference between the name plate voltage and the
supplied voltage? - ANS + or - 10%
What is the voltage between any two hot lines of a 230 volt delta power supply? - ANS 230V
what is the voltage between a hot line and ground on a 240 volt delta power supply - ANS No
usable voltage
what is the voltage between any two hot lines of a 230 volt grounded delta power supply -
ANS 230V
draw a diagram of a 230 volt grounded delta power supply. label all of the voltages and the wild
leg - ANS
what is the wild leg? - ANS leg with higher than 120v to ground or neutral
what danger is the wild leg? - ANS high voltage that will damage 120v component in the
circuit
3 @COPYRIGHT 2025/2026 ALLRIGHTS RESERVED.
, what is the voltage between either of the non wild leg hot lines and neutral in a 230 volt
grounded delta system? - ANS 115v
how do you determine which hot line is the wild leg in a 250 volt grounded delta power supply?
- ANS 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? - ANS crossing the hot lines and supplying the wild leg to the wrong terminal
in the unit.
Why is a "WYE" power supply so versatile - ANS 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? - ANS 208v
What is the voltage between any hot line and neutral or ground in a 208 volt WYE power
supply? - ANS 120v
What is the voltage from any hot line to ground or neutral, on a 480 volt WYE power supply? -
ANS 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? - ANS 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? - ANS 1
4 @COPYRIGHT 2025/2026 ALLRIGHTS RESERVED.
AND CORRECT ANSWERS. VERIFIED
2025/2026.
What do the following prefixes mean? Micro,Kilo,Mega,Milli - ANS 1/1,000,000, 1000,
1,000,000, 1/1000
If you know the wattage and voltage, how do you determine the current? - ANS Divide the
wattage by the voltage
If you know the voltage and current how do you determine the wattage? - ANS 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? - ANS .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? - ANS 4160 Watts
How much voltage is in one hot line? - ANS None
What happens to current in a parallel circuit? - ANS It divides across resistances
1 @COPYRIGHT 2025/2026 ALLRIGHTS RESERVED.
,what happens to voltage across the loads in a parallel circuit? - ANS stays the same
what happens to the voltage across the loads in a series circuit? - ANS it divides across the
resistances
what happens to the current in a series circuit? - ANS It stays the same everywhere
in a parallel circuit the total resistance of the circuit will always be less than what resistance? -
ANS the smallest resistance
how do you find the total resistance of a series circuit? - ANS add the resistances together
how do you find the total resistance of a parallel circuit? - ANS 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? - ANS 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? - ANS 240 volts
What is the advantage of using higher voltages? - ANS Lower Current and wire size
Is there a negative and positive line in AC power supplies? - ANS No
What is the voltage between two hot lines in a 230-volt system? - ANS 230V
2 @COPYRIGHT 2025/2026 ALLRIGHTS RESERVED.
,What is the voltage between two hot lines in a 208-volt system? - ANS 208V
What is the voltage between a hot line and a neutral in a 230-volt single phase supply? -
ANS 115V
What is the voltage between a hot line and a neutral in a 208-volt single phase supply? -
ANS 120V
What is the accepted maximum voltage difference between the name plate voltage and the
supplied voltage? - ANS + or - 10%
What is the voltage between any two hot lines of a 230 volt delta power supply? - ANS 230V
what is the voltage between a hot line and ground on a 240 volt delta power supply - ANS No
usable voltage
what is the voltage between any two hot lines of a 230 volt grounded delta power supply -
ANS 230V
draw a diagram of a 230 volt grounded delta power supply. label all of the voltages and the wild
leg - ANS
what is the wild leg? - ANS leg with higher than 120v to ground or neutral
what danger is the wild leg? - ANS high voltage that will damage 120v component in the
circuit
3 @COPYRIGHT 2025/2026 ALLRIGHTS RESERVED.
, what is the voltage between either of the non wild leg hot lines and neutral in a 230 volt
grounded delta system? - ANS 115v
how do you determine which hot line is the wild leg in a 250 volt grounded delta power supply?
- ANS 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? - ANS crossing the hot lines and supplying the wild leg to the wrong terminal
in the unit.
Why is a "WYE" power supply so versatile - ANS 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? - ANS 208v
What is the voltage between any hot line and neutral or ground in a 208 volt WYE power
supply? - ANS 120v
What is the voltage from any hot line to ground or neutral, on a 480 volt WYE power supply? -
ANS 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? - ANS 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? - ANS 1
4 @COPYRIGHT 2025/2026 ALLRIGHTS RESERVED.
