Electrical level 4 - Mod 1 - Load
Calculations, Feeders and Services
UPDATED ACTUAL Exam Questions and
CORRECT Answers
Feeder - CORRECT ANSWER - All circuit conductors between the service equipment, the
source of a separately derived system, or other power supply source and the final branch-circuit
overcurrent device.
Service - CORRECT ANSWER - The conductors and equipment for delivering electric
energy from the serving utility to the wiring system of the premises served.
Tap Conductors - CORRECT ANSWER - A conductor that has overcurrent protection
ahead of its point of supply that exceeds the value permitted for similar conductors that are
protected.
Feeder Circuit - CORRECT ANSWER - The purpose of _____ _____ load calculations is
to determine the size of these overcurrent protection devices and the circuit conductors using
NEC requirements. Typically supply transformers, motor control centers, and subpanels.
NEC Article 215 - CORRECT ANSWER - What NEC Article covers feeder circuits? It
goes on to state that feeders shall have an ampacity that is not less than that required to supply
the load.
Feeder-Circuit Conductor Size - CORRECT ANSWER - The minimum
________________ shall have an allowable ampacity of not less than 100% of the non-
continuous load plus 125% of the continuous load.
125% or a multiplier of 1.25 - CORRECT ANSWER - The factor for a CONTINUOUS
load.
, 100% or a multiplier of 1 - CORRECT ANSWER - The factor for a NON-CONTINUOUS
load.
Branch Circuits, Feeders, and Services - CORRECT ANSWER - What are the three
electrical calculation sections? (Not of the NEC)
Sequence of Calculating Loads - CORRECT ANSWER - 1.) Determine the load on branch
circuits. 2.) Calculate the feeder load. 3.) Determine the service load.
Increased in Size (NEC SECTION 110.14c) - CORRECT ANSWER - After complying
with the NEC, the conductors may have to be __________ to accomodate the altered alloawable
ampacity for that conductor.
3 Hours or More - CORRECT ANSWER - A continuous duty load is a load that operates
without ANY interruption.
Reciprocals (multiplicative inverses) - CORRECT ANSWER - When derating, these can
be used to quickly find a conductor to serve a load. Typically shown on a calculator as 1/x. [Ex. 3
(1/x) = 1/3]
Voltage Drop for Feeders - CORRECT ANSWER - The NEC recommends that "this"
shouuld not exceed 3% to the farthest outlet, and 5% for the combination of feeders and branch
circuits to the farthest outlet.
Formula for Voltage Drop - CORRECT ANSWER - VD= 2xLxIxR / 1000
CM - CORRECT ANSWER - What is used to represent the area of the conductor in
"circular mils" of a voltage drop formula?
K - CORRECT ANSWER - What letter is used to represent the constant of a voltage drop
formula?
Calculations, Feeders and Services
UPDATED ACTUAL Exam Questions and
CORRECT Answers
Feeder - CORRECT ANSWER - All circuit conductors between the service equipment, the
source of a separately derived system, or other power supply source and the final branch-circuit
overcurrent device.
Service - CORRECT ANSWER - The conductors and equipment for delivering electric
energy from the serving utility to the wiring system of the premises served.
Tap Conductors - CORRECT ANSWER - A conductor that has overcurrent protection
ahead of its point of supply that exceeds the value permitted for similar conductors that are
protected.
Feeder Circuit - CORRECT ANSWER - The purpose of _____ _____ load calculations is
to determine the size of these overcurrent protection devices and the circuit conductors using
NEC requirements. Typically supply transformers, motor control centers, and subpanels.
NEC Article 215 - CORRECT ANSWER - What NEC Article covers feeder circuits? It
goes on to state that feeders shall have an ampacity that is not less than that required to supply
the load.
Feeder-Circuit Conductor Size - CORRECT ANSWER - The minimum
________________ shall have an allowable ampacity of not less than 100% of the non-
continuous load plus 125% of the continuous load.
125% or a multiplier of 1.25 - CORRECT ANSWER - The factor for a CONTINUOUS
load.
, 100% or a multiplier of 1 - CORRECT ANSWER - The factor for a NON-CONTINUOUS
load.
Branch Circuits, Feeders, and Services - CORRECT ANSWER - What are the three
electrical calculation sections? (Not of the NEC)
Sequence of Calculating Loads - CORRECT ANSWER - 1.) Determine the load on branch
circuits. 2.) Calculate the feeder load. 3.) Determine the service load.
Increased in Size (NEC SECTION 110.14c) - CORRECT ANSWER - After complying
with the NEC, the conductors may have to be __________ to accomodate the altered alloawable
ampacity for that conductor.
3 Hours or More - CORRECT ANSWER - A continuous duty load is a load that operates
without ANY interruption.
Reciprocals (multiplicative inverses) - CORRECT ANSWER - When derating, these can
be used to quickly find a conductor to serve a load. Typically shown on a calculator as 1/x. [Ex. 3
(1/x) = 1/3]
Voltage Drop for Feeders - CORRECT ANSWER - The NEC recommends that "this"
shouuld not exceed 3% to the farthest outlet, and 5% for the combination of feeders and branch
circuits to the farthest outlet.
Formula for Voltage Drop - CORRECT ANSWER - VD= 2xLxIxR / 1000
CM - CORRECT ANSWER - What is used to represent the area of the conductor in
"circular mils" of a voltage drop formula?
K - CORRECT ANSWER - What letter is used to represent the constant of a voltage drop
formula?
