FE Electrical & Computer Practice Question Solution included after investigation
CASE E-030 Β· FE

The Feeder That Delivered 228 V Instead of 240 V

The source measured 240 V. The load saw only 228 V because the feeder resistance was treated as one-way.

β–Ά INTERACTIVE CASE FILE β€’ 5–10 MIN β€’ CLICK TO INVESTIGATE

Inspect, commit, prove, fix, and sign off.

Case E-030 engineering failure visual
HOW THIS WORKS

Think like
a real engineer.

Follow the investigation process used in the field β€” in five guided steps.

1

Inspect

Review the problem, diagram, and evidence.

2

Commit

Choose your hypothesis.

3

Prove

Run calculations and test your idea.

4

Fix

Select and validate a safe correction.

5

Sign Off

See the full debrief and key takeaways.

Case Brief

SAME PRINCIPLES. HIGHER STANDARDS.
PROBLEM STATEMENT

A 240 V single-phase source supplies a 30 A load through a two-wire feeder. Each conductor has 0.20 Ξ© resistance. The design note predicts only a 6 V drop, but the load measures about 228 V. Diagnose the path error, calculate actual voltage drop and feeder loss, and choose a correction that cuts the drop in half.

Power Systems Electrical & Computer Design Verification Root Cause Analysis Safe Correction
E-030
INVESTIGATION WORKSPACE WORK THROUGH THE CASE β€” YOUR CHOICES MATTER.
πŸ”’
DEBRIEF (LOCKED)

Complete the investigation
to unlock the full debrief.

Find the root cause, confirm the fix, and see how this connects to the exam.

πŸ”’Root causeComplete the case
to reveal
πŸ”’Correct fixComplete the case
to reveal
πŸ”’Exam takeawayComplete the case
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CASE CLOSED Β· ENGINEERING VERDICT

What actually failed β€” and what should change.

What failed

The load received 228 V.

What was assumed

Only one conductor resistance was included.

Corrected model

Use full loop resistance for voltage drop and IΒ²R loss.

QUICK ANSWER

For a two-wire single-phase feeder, current travels through both conductors. If each is 0.20 Ξ©, the loop is 0.40 Ξ©. At 30 A, the drop is 12 V, so a 240 V source delivers about 228 V.

ENGINEERING TAKEAWAY

Use total loop resistance: Rloop = Rout + Rreturn, then Ξ”V = I Rloop and Ploss = IΒ² Rloop.

CASE QUESTIONS

Questions this case should settle.

Do you include both conductors in single-phase voltage drop?

Yes. Use the resistance of the complete out-and-back path.

What is the feeder loss at 30 A and 0.40 Ξ©?

IΒ²R = 360 W.

NEXT FE PRACTICE QUESTION

The 8 Ohm Load That Became 128 Ohms

Power Systems Β· 5–10 min

Continue Practice β†’
WHAT YOU’LL LEARN

Real failures. Lasting skills.

Each case is designed to build the judgment, analysis, and confidence you need for engineering exams β€” and beyond.

  • Apply core engineering concepts to real-world problems
  • Practice structured troubleshooting and analysis
  • Strengthen exam-ready thinking through realistic scenarios
COMMON QUESTIONS
Do I need prior knowledge to use these cases?

Basic subject familiarity helps, but every case is designed to teach through the investigation itself.

How long does a case take?

Most cases are designed for a focused 5–10 minute investigation.

Are the cases aligned with engineering exams?

Each case is mapped to a verified exam, subject, topic, and misconception before publication.

What happens after I complete a case?

The sealed debrief unlocks with the root cause, corrected reasoning, fix, and takeaway.