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20 multiple-choice questions and 11 flashcards on Focus Four — Electrocution, about 7% of the OSHA 30 bank. Every one carries a written rationale.
Focus Four — Electrocution is one of 10 chapters in CoStudy's OSHA 30 (Construction) bank, and it holds 20 of the bank's 300 multiple-choice questions — roughly 7% of the total. That proportion is not arbitrary: chapters follow the certifying body's published exam outline, and the number of questions in each is set by that domain's published weight, so the share of your practice time this chapter takes matches the share of the real exam it accounts for.
Studying by chapter is worth doing once you have a diagnostic score. A single overall percentage tells you whether you are close; it does not tell you which domain is dragging. Working a weak chapter in isolation, and re-testing it in isolation, is the fastest way to move a score that has stalled — and it is why the mock exams in CoStudy report by domain rather than as one number.
5 questions drawn from this chapter, with the full rationale shown — the controlling principle behind the right answer, and why each wrong option tempts and fails.
A GFCI is designed to trip at a ground-fault current of approximately:
Answer: A — 5 milliamps
Off-by-one trap. ~4–6 mA.
Lockout/tagout (LOTO) is primarily governed by:
Answer: D — 29 CFR 1910.147
A is confined spaces; B is fall protection; C is recordkeeping; D correct.
Power line clearance for ≤50 kV:
Answer: B — 10 ft
A/C/D) Wrong. B) Correct.
For temporary power on a construction site, which two approaches are acceptable for protecting workers using cord-connected tools?
Answer: B — Ground-fault circuit interrupters or an assured grounding program
B) Correct — the standard recognizes GFCI protection or an assured equipment grounding conductor program as the two acceptable approaches. A) Labels and reminders are not either recognized approach. C) Overcurrent devices protect conductors, not people, from shock. D) PPE-first thinking that skips the required system-level protection.
NFPA 70E identifies arc-flash PPE in categories numbered:
Answer: A — 1 to 4
PPE Categories 1 through 4 in NFPA 70E.
4 cards from the 11 in this chapter.
How does a GFCI protect a worker, and at what leakage level does it trip?
It compares current on the hot and neutral conductors and opens the circuit when the imbalance reaches roughly 5 milliamps, before the current level becomes lethal. It does not protect against line-to-line contact.
Lockout/tagout (LOTO)?
Procedure to isolate energy sources before maintenance: identify, notify, shutdown, isolate, lock/tag, verify zero energy. 29 CFR 1910.147 (general) + 1926 references.
What are the six steps of a basic lockout/tagout procedure?
Prepare and notify affected workers • Shut down equipment • Isolate all energy sources • Apply locks and tags • Release stored (residual) energy • Verify zero energy before work.
What is the minimum clearance for equipment operating near overhead power lines up to 50 kV?
10 feet for general equipment. For cranes under 1926.1408, 20 feet unless the voltage is known and the table clearance or an encroachment-prevention option is used.
These are a sample. The full Focus Four — Electrocution chapter runs 31 items with per-chapter progress tracking, on the web and in the iOS app.