ESAA Intermediate Level Exam common mistakes
ESAA Intermediate Level Exam · Understand the traps and how to avoid them.
Treating motor horsepower as input power and using it directly in current or efficiency calculations, so full-load current, kW input, and heat loss figures all come out wrong.
Nameplate horsepower is shaft output, and candidates memorize 'HP = volts × amps × 1.732' without the efficiency and power factor terms that convert electrical input to mechanical output. The formula looks familiar, so the missing denominator goes unnoticed.
What to do instead
Write the conversion chain on scratch paper before computing: input watts = HP × 746 / (efficiency), and input watts = √3 × V × I × PF for three-phase. Solve for the unknown only after both expressions are written, and sanity-check that output HP is always less than input kVA converted to HP.
Applying the motor's nameplate voltage and current rating to a VFD-fed motor as if it were across-the-line, then sizing conductors, overloads, or drive output current from that number.
Candidates learn the NEC motor tables and the drive section separately and never reconcile them. The drive's output current rating, the motor's service factor, and the 1.0 vs 1.15 SF derating rules for inverter duty blur together under time pressure.
What to do instead
Separate the two questions explicitly: branch circuit and disconnect sizing follow the motor tables plus the drive's input current rating, while overload protection follows the motor's actual nameplate FLA and the drive's programmable overload setting. Practice one worked example of each path side by side until the two rule sets stop merging.
Reading a process measurement as the true value without applying the transmitter's zero and span, the 4 mA live zero, or the square-root extraction for a differential-pressure flow element.
A 4–20 mA signal is linear in the measured variable only after scaling, and DP flow is proportional to the square of flow. Candidates convert mA to percent, stop there, and report a flow that is wrong by the square root factor, or they forget that 4 mA equals zero percent, not zero mA.
What to do instead
Always state the transfer function before converting: percent = (mA − 4)/16 × 100, then apply the process relation (linear, or flow = full scale × √percent). For DP flow, verify with a known point such as 25 percent DP equals 50 percent flow, and check that the transmitter's configured LRV and URV match the element's calibrated range.
Diagnosing a PLC input fault by assuming the field device is bad, without first checking the input module's common, the sinking versus sourcing configuration, and the actual voltage at the terminal.
PLC input wiring conventions vary by module family, and a field device that works when jumpered may still fail because the module common is not referenced to the supply it expects. Candidates jump to the sensor because it is the visible component.
What to do instead
Use a fixed sequence: measure voltage at the input terminal with the field device both energized and de-energized, confirm the module's input type and common wiring against the drawing, then force the input in the programming software to split module faults from field faults. Only after the module is proven good do you test the device.
Stating that a fuse or breaker protects a motor against overload, or that the overload relay protects against short circuit, and then selecting the wrong device for the wrong fault.
Both devices sit in the same starter enclosure and both 'protect the motor', so the distinction collapses. Candidates memorize trip classes and interrupting ratings without mapping each device to the fault current and time scale it addresses.
What to do instead
Build a two-column comparison in your notes: short-circuit and ground-fault protection (instantaneous, high current, breaker or fuse sized to the motor tables) versus overload protection (thermal, sustained slight overcurrent, sized to nameplate FLA and service factor). For every practice question, name the fault type first, then pick the device.
Answering arc flash or shock questions using approach boundaries and PPE categories from memory of an older edition, or mixing NFPA 70E boundary names with the wrong voltage or equipment condition.
The standard is revised on a cycle, tables are renumbered, and incident energy depends on the specific equipment label rather than a generic category. Candidates study a summary sheet that has drifted out of date.
What to do instead
Anchor answers to the equipment's arc flash label and the current edition's definitions: limited, restricted, and arc flash boundaries, and the requirement that energized work be justified before any PPE discussion. When a question gives an incident energy value, use it directly rather than recalling a category table.
Jumping to a component replacement based on the reported symptom instead of gathering evidence in a fixed order, so the first 'fix' is a guess and the real cause returns.
Symptom-to-part shortcuts feel efficient under exam time pressure, and many practice scenarios reward the obvious answer. Real faults are often upstream: a loose neutral, a blown control fuse, or an open interlock explains several 'failed' devices at once.
What to do instead
Apply a repeatable sequence on every troubleshooting item: verify the symptom, check power and control voltage at the source, trace the circuit in order, isolate by substitution or forcing, then confirm the repair under load. State which measurement would distinguish the top two hypotheses before naming the failed part.
Confusing power factor with efficiency, or treating them as interchangeable when computing current draw, kVA demand, or utility penalty.
Both are dimensionless ratios below one that appear in the same motor discussion, and both reduce the useful output for a given input. Candidates pick whichever term the answer choices seem to favor.
What to do instead
Define each in one sentence and keep them apart: power factor is real power divided by apparent power (phase relationship between volts and amps), efficiency is useful output divided by total input (losses). Work one problem where PF is corrected with capacitors at constant kW and note that efficiency does not change.
Misreading a wiring diagram's control circuit by ignoring the difference between normally open and normally closed contacts as drawn versus as actuated, and by missing the holding contact in a start-stop circuit.
Schematics show contacts in their de-energized state, while the physical device may be actuated in service. Candidates read the drawing literally and predict the wrong state after the start button is released.
What to do instead
Before answering, redraw the circuit in its energized state: mark each contact open or closed as it actually is, trace the path from control transformer through the coil, and identify which contact seals around the start button. Verify the stop circuit is wired as a series break, not a parallel path.
Skipping the preventive maintenance reasoning behind a reliability question and answering from a generic 'replace it more often' instinct rather than from failure-mode or condition-monitoring logic.
Maintenance questions often describe a symptom and ask for the correct action, and candidates default to the most conservative-sounding option. That ignores the difference between time-based and condition-based tasks and between failure modes that benefit from inspection versus those that do not.
What to do instead
Classify the described failure mode first (wear-out, random, or condition-indicated), then choose the task type that addresses it: scheduled replacement for wear-out, condition monitoring such as vibration or thermography for developing faults, and failure-finding for hidden protective functions. Reject any option that adds work without naming the failure mode it prevents.