NEIEP Mechanic Exam common mistakes
NEIEP Mechanic Exam · Understand the traps and how to avoid them.
When calculating total load on a hoisting system, the candidate adds the car weight, rated load, and counterweight but forgets to include the weight of the suspension ropes (and traveling cables) in the traction calculation, or uses the counterweight imbalance incorrectly.
Candidates memorize the basic formula (car + load − counterweight) and treat ropes as negligible, but on high-rise units the rope weight is a significant portion of the load and changes the traction and motor sizing. They also confuse the counterweight balance point (typically 40–50% of rated load) with a 100% balance.
What to do instead
Write the full static force balance for the worst-case position (car at bottom, full load; car at top, empty) including rope weight per side and traveling cable. Practice with a numerical example where rope weight is 8–10% of rated load and verify that the imbalance never exceeds the machine's traction capability. Remember the counterweight is sized to balance the car plus 40–50% of rated load, not the full load.
On a wiring/control schematic question, the candidate traces a circuit by assuming that a normally closed (NC) contact is closed only when the coil is energized, or misreads a seal-in (holding) contact as a limit switch.
Candidates learn relay logic from ladder diagrams but do not consistently apply the convention that NC contacts are drawn closed in the de-energized state. They also confuse the holding contact (wired in parallel with the start button) with a safety-string contact.
What to do instead
Before answering, redraw the rung in the de-energized state and label each contact as 'closed when de-energized' or 'closed when energized.' Trace the circuit step by step from the power rail through the safety string to the coil. Practice identifying seal-in contacts by their parallel connection across the start device.
During a maintenance scenario, the candidate proposes adjusting or bypassing a safety device (e.g., door interlock, governor switch, final limit) to clear a fault, rather than diagnosing the root cause.
Exam questions often present a 'nuisance trip' symptom, and candidates choose the fastest fix (jumper the switch) because they have seen it done in the field. They underestimate how strictly the exam enforces code-compliant troubleshooting.
What to do instead
Adopt a rule: no safety device is ever bypassed for troubleshooting except with a documented, controlled procedure and never left bypassed. For each safety device, memorize its function, its test procedure, and the code requirement (e.g., ASME A17.1 door interlock must prevent car motion unless doors are closed and locked). When a question offers 'bypass' as an answer, eliminate it first.
The candidate calculates elevator traffic or handling capacity using the wrong formula, e.g., uses the building population instead of the peak-hour demand, or forgets to convert between passengers per hour and cars required.
Traffic analysis involves several chained formulas (population, peak demand, round-trip time, handling capacity) and candidates mix up which variable goes where. They also forget that round-trip time includes door dwell and acceleration/deceleration penalties.
What to do instead
Memorize the chain: building population = floor area × occupancy density; peak-hour demand = population × peak factor; handling capacity = (300 × car capacity) / round-trip time; cars required = demand / handling capacity. Work through a full example with a 10-story office building and verify units at each step.
When asked to identify the correct rigging or scaffolding setup for installing a machine or escalator truss, the candidate selects a method based on convenience rather than on load rating, center of gravity, and code-required inspection.
Candidates focus on the installation sequence and overlook the rigging hardware (shackles, slings, beam clamps) and the requirement for a pre-lift inspection. They also forget that escalator trusses are long and flexible and need multiple pick points.
What to do instead
For every rigging question, first identify the load weight and center of gravity, then check the working load limit (WLL) of each component with a safety factor (typically 5:1 for slings). Memorize that a pre-use inspection of rigging is mandatory and that tag lines are required for long loads. Practice matching sling types (wire rope, synthetic, chain) to load and environment.
The candidate misdiagnoses an escalator handrail or step-chain fault by replacing the handrail drive when the actual cause is a worn step chain or a misadjusted tension carriage.
Handrail speed and step speed are linked through the drive, so a handrail symptom can originate in the step chain. Candidates jump to the most visible component (handrail) instead of checking the drive chain tension, the tension carriage, and the step chain elongation.
What to do instead
Follow a diagnostic sequence: check handrail speed relative to step speed (should be 0–2% faster), inspect the handrail drive belt/chain, then measure step chain elongation and tension carriage position. Know the wear limits (e.g., step chain elongation typically limited to 1.5–2% depending on manufacturer) and that a misadjusted tension carriage causes both handrail and step speed faults.
On a code question, the candidate cites a general requirement but misses the specific exception or the edition/year of the code that applies, or confuses ASME A17.1 with A17.3 (existing installations).
Codes are long and candidates study summaries rather than the actual clause structure. They do not consistently note that A17.1 covers new installations and A17.3 covers existing installations, and that local amendments may apply.
What to do instead
Build a one-page map of the code: A17.1 (new), A17.3 (existing), A17.5 (components), A17.6 (suspension), plus the applicable local code. For each safety topic (door interlocks, pit ladders, machine-room access, escalator clearances), write the clause number and the key dimension. When answering, state the code and edition before the requirement.
The candidate calculates motor horsepower or current for a given load and speed but forgets to include the counterweight, the efficiency of the machine/gearbox, or the acceleration torque.
The basic formula P = F × v is memorized, but candidates plug in the full load instead of the unbalanced load and ignore efficiency (typically 0.7–0.85 for geared machines) and acceleration. They also mix units (lb vs. N, ft/min vs. m/s).
What to do instead
Use the full equation: P = (F_unbalanced × v) / (33000 × η) for horsepower in US units, where F_unbalanced = (car + load − counterweight) plus rope weight difference, and η is the mechanical efficiency. Add acceleration torque using T = Iα or the equivalent linear form. Always carry units and convert ft/min to ft/s before dividing.
When answering a lockout/tagout (LOTO) or pit-entry question, the candidate lists the steps in the wrong order or omits verification of zero energy (try-out) and the removal of stored energy (e.g., hydraulic pressure, capacitors, counterweight).
Candidates memorize the acronym but not the sequence, and they forget that elevators store energy in the counterweight, hydraulic accumulators, and controller capacitors. They also skip the try-out step because it seems redundant.
What to do instead
Memorize the six-step LOTO sequence: notify, shut down, isolate, lock and tag, release stored energy, verify zero energy. For elevators, add: park the car at a landing, set the car top/pit stop switch, block the counterweight, and relieve hydraulic pressure. Practice writing the sequence for a pit entry and a controller repair.
The candidate confuses the function of the governor and the safety gear, e.g., states that the governor directly stops the car or that the safety gear is engaged by the final limit switch.
The governor, safety gear, and final limit are all overspeed/over-travel devices, and candidates blur their roles. They also forget that the governor trips the safety gear mechanically via a rope and linkage, and that the final limit switch cuts power but does not mechanically stop the car.
What to do instead
Draw the chain: overspeed → governor flyweights extend → governor rope grips → safety gear linkage pulls wedges → safety gear grips guide rails. Separately, over-travel → final limit switch opens → power removed. Memorize the governor trip speed formula (typically 115% of rated speed) and the safety gear test procedure (no-load and full-load tests).