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ELECTRICAL LEVEL 4-MOD 1 - LOAD CALCULATIONS, FEEDERS AND SERVICES EXAM
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ELECTRICAL LEVEL 4-MOD 1 - LOADCALCULATIONS, FEEDERS AND SERVICES
EXAM 2024-2025
Feeder - Answer All circuit conductors connect the service equipment, the source
of a separately derived system, or another power supply source to the final
branch-circuit overcurrent device.
Service: ANSWER The cables and equipment used to carry electric energy from
the serving utility to the served premises' wiring systems.
Tap Conductors - Answer A conductor with overcurrent protection ahead of its
point of supply that exceeds the maximum value allowed for similarly protected
conductors.
Feeder Circuit - Answer The goal of ______ load calculations is to establish the
size of these overcurrent safety devices and circuit wires based on NEC standards.
Typically provide transformers, motor control centres, and subpanels.
NEC Article 215: ANSWER What NEC article addresses feeder circuits? It goes
on to clarify that feeders must have at least the ampacity required to serve the load.
Feeder-Circuit Conductor Size - Answer The minimum permissible ampacity for
________________ is 100% of the non-continuous load + 125% of the continuous
load.
ANSWER The factor for a CONTINUOUS load is 125% or a 1.25 multiplication.
100% or a multiplier of one - ANSWER The factor for a non-continuous load.
, Branch Circuits, Feeders, and Services - Answer What are the three electrical
calculation sections? (Not from the NEC.)
Sequence of Calculating Loads - Answer 1.) Determine the load on the branch
circuits. 2. Calculate the feeder load. 3. Determine the service load.
increased in size (NEC SECTION 110.14c) - ANSWER After complying with the
NEC, the conductors may need to be adjusted to accommodate the revised
allowable ampacity for that conductor.
3 Hours or More - Answer A constant duty load is one that functions without any
interruptions.
Reciprocals (multiplicative inverses): ANSWER When derating, these can be
utilised to quickly locate a conductor to service a load. A calculator will typically
display 1/x. [Ex. 3 (1/x) = 1/3]
Voltage Drop for Feeders - Answer The NEC advises that "this" should not be
more than 3% to the farthest outlet, and 5% for the combination of feeders and
branch circuits.
The formula for voltage drop is VD= 2xLxIxR/1000.
CM- ANSWER In a voltage drop formula, how is the conductor's area represented
in "circular mils"?
K: ANSWER Which letter is used to denote the constant in a voltage drop formula?
ANSWER: Copper (12.9) and Aluminium (21.2) What are the constants for copper
and aluminium conductors?
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