STSC Exam Flashcards

Q: How many flashcards are in this set?

This set includes 50 original cards covering 29 CFR 1926 standards, the Fatal Four, fall protection and scaffolds, excavation, electrical safety and LOTO, silica and industrial hygiene, fire and confined space, PPE, and construction safety leadership.

Q: What is the difference between STS and STSC?

STS (Safety Trained Supervisor) is a general-industry credential built around 29 CFR 1910, while STSC (Safety Trained Supervisor Construction) is built entirely around 29 CFR 1926 construction standards, with heavy emphasis on fall protection, scaffolds, excavation, cranes, steel erection, and silica. Construction supervisors should pursue the STSC.

Question 1

What are the Fatal Four in construction?

Accepted Answer

Falls, struck-by, caught-in/between, and electrocutions. They cause roughly 60% of construction worker deaths each year (BLS CFOI). Most of 29 CFR 1926 and OSHA's emphasis programs target these four, so they dominate the STSC.

Question 2

Hierarchy of controls: order most to least effective

Accepted Answer

Elimination, substitution, engineering controls, administrative controls, then PPE. Higher levels physically remove or reduce the hazard; PPE only protects the individual wearer and depends on correct use, so it is the last resort.

Question 3

Why is PPE considered the least effective control?

Accepted Answer

PPE does not remove the hazard. It only reduces exposure for one worker and fails if it is the wrong type, worn incorrectly, damaged, or removed. Engineering controls protect everyone in the area regardless of behavior.

Question 4

Caught-in/between vs. struck-by: the distinction

Accepted Answer

Struck-by means a moving object strikes the worker (falling tool, swinging load, vehicle). Caught-in/between means the worker is crushed, pinched, or compressed between objects or by collapsing material, such as a trench cave-in or being pinned by equipment.

Question 5

What is Stop Work Authority?

Accepted Answer

The right and duty of any worker to halt a task when an imminent or uncontrolled hazard appears, without fear of reprisal. It shifts safety from a supervisor-only decision to a shared responsibility and is a hallmark of a strong safety culture.

Question 6

What is the 6-foot fall protection trigger?

Accepted Answer

Under 29 CFR 1926.501, workers on a walking/working surface with an unprotected edge 6 feet or more above a lower level must use guardrails, safety nets, or a personal fall arrest system. (General industry under 1910 uses 4 feet.)

Question 7

Required guardrail top-rail height in construction

Accepted Answer

42 inches plus or minus 3 inches (39 to 45 inches) above the surface, per 1926.502(b). The top rail must withstand 200 pounds of outward or downward force, and a midrail sits at about half that height.

Question 8

The ABCs of a Personal Fall Arrest System (PFAS)

Accepted Answer

Anchorage, Body harness (full-body), and Connecting device (shock-absorbing lanyard or self-retracting lifeline). Body belts have been prohibited for fall arrest since 1998 because they concentrate arrest forces on the abdomen.

Question 9

Minimum anchor strength for personal fall arrest

Accepted Answer

5,000 pounds per attached worker, unless the anchorage is engineered as part of a complete system with a safety factor of at least two under a qualified person's supervision (1926.502(d)(15)).

Question 10

Why does fall protection trigger at 10 feet on scaffolds?

Accepted Answer

Scaffolds fall under Subpart L (1926.451(g)), which sets the fall protection threshold at more than 10 feet, not the 6-foot general trigger. Knowing that scaffolds, steel erection, and general work each have different triggers is a common STSC trap.

Question 11

Maximum free-fall distance in a PFAS

Accepted Answer

A personal fall arrest system must limit free fall to 6 feet or less and stop the worker before contacting a lower level. It must also limit arresting force on the body to 1,800 pounds when used with a full-body harness.

Question 12

What is a controlled access zone (CAZ)?

Accepted Answer

A bounded area where certain work (like leading-edge or overhand bricklaying) may proceed without conventional fall protection, entered only by authorized workers. It is paired with a safety monitoring system as an alternative measure, not a default.

Question 13

Scaffold platform: how big can plank gaps be?

Accepted Answer

Gaps between planks and between the platform and uprights must be no more than 1 inch, per 1926.451(b). Wider gaps (up to 9.5 inches) are allowed only where the configuration cannot be fully planked. Platforms must also be fully decked.

Question 14

Who must inspect a scaffold, and when?

Accepted Answer

A competent person, before each work shift and after any event that could affect structural integrity (1926.451(f)(3)). A competent person can both identify hazards and is authorized to take prompt corrective action.

Question 15

Scaffold height-to-base ratio limit before restraint

Accepted Answer

When a supported scaffold's height exceeds 4 times its minimum base width, it must be restrained from tipping by guying, tying, or bracing. Tip-over from excessive height-to-base ratio is a leading scaffold fatality cause.

Question 16

How far must an extension ladder reach above the landing?

Accepted Answer

At least 3 feet above the upper landing surface (1926.1053(b)(1)). If it cannot extend 3 feet, secure the top and provide a grab rail. This gives a worker something to hold while stepping off.

Question 17

The 4-to-1 ladder pitch rule

Accepted Answer

A portable straight or extension ladder should be set so its base is 1 foot out from the wall for every 4 feet of working height (a 75-degree angle). Too steep risks tipping backward; too shallow risks the base sliding out.

Question 18

Why can't cross-braces be used as scaffold access?

Accepted Answer

Cross-braces are diagonal and not designed as a climbing surface, so 1926.451(e) prohibits using them for access. Workers must use a ladder, stair tower, ramp, or integral prefabricated access when the platform is more than 2 feet above the access point.

Question 19

Three soil classifications for excavations

Accepted Answer

Type A (most stable cohesive soil, e.g., clay), Type B (moderately stable), and Type C (least stable, e.g., gravel, sand, or submerged soil). Classification determines the allowable sloping angle and protective system.

Question 20

Maximum allowable slope for Type A, B, and C soil

Accepted Answer

Type A slopes at 3/4:1 (about 53 degrees), Type B at 1:1 (45 degrees), and Type C at 1.5:1 (about 34 degrees). Less stable soil requires a flatter, wider cut to prevent cave-in.

Question 21

When is a protective system required in a trench?

Accepted Answer

At 5 feet deep or more, unless the excavation is entirely in stable rock. Below 5 feet a competent person may waive it only if the soil shows no potential for cave-in. At 20 feet or deeper the system must be engineered.

Question 22

Spoil pile setback from a trench edge

Accepted Answer

Excavated soil, materials, and equipment must be kept at least 2 feet from the trench edge (1926.651(j)). This prevents material from rolling back in and reduces surcharge load that can trigger a wall collapse.

Question 23

Egress requirement for trenches 4 feet or deeper

Accepted Answer

A ladder, ramp, stairway, or other safe means of exit must be within 25 feet of lateral travel for every worker (1926.651(c)). This lets workers escape quickly if the trench begins to fail.

Question 24

Sloping vs. shoring vs. shielding

Accepted Answer

Sloping/benching cuts the walls back to a safe angle. Shoring (e.g., hydraulic) braces the walls in place. Shielding (a trench box) does not stop a cave-in but protects workers inside it. All three are accepted protective systems.

Question 25

What must happen before workers enter an excavation each day?

Accepted Answer

A competent person inspects the excavation, adjacent areas, and protective systems daily and as conditions change (rain, vibration, added load). If hazardous conditions are found, workers are removed until corrected.

Question 26

What is GFCI protection and where is it required?

Accepted Answer

A Ground-Fault Circuit Interrupter cuts power within milliseconds when current leaks to ground. Under 1926.404, all 120V single-phase 15- and 20-amp receptacles on a construction site must have GFCI protection, or an Assured Equipment Grounding Conductor Program must be used instead.

Question 27

GFCI vs. circuit breaker: what each protects

Accepted Answer

A breaker protects equipment and wiring from overload and short circuits (high current). A GFCI protects people from electrocution by tripping on small ground-fault current (as little as 5 milliamps). They guard against different failures and are not interchangeable.

Question 28

Purpose of lockout/tagout (LOTO)

Accepted Answer

LOTO isolates and de-energizes a machine or circuit, then locks the energy-isolating device so it cannot be re-energized while workers service it. It controls hazardous energy, electrical, hydraulic, pneumatic, mechanical, thermal, and gravity, not just electricity.

Question 29

Lock vs. tag in lockout/tagout

Accepted Answer

A lock physically prevents the device from being operated; a tag only warns. A tag alone is allowed only when a device cannot accept a lock, and it must give protection equivalent to a lock. Locks are always the preferred, more reliable control.

Question 30

Minimum approach for unqualified persons near overhead power lines

Accepted Answer

Equipment and unqualified workers must stay clear of energized overhead lines, generally at least 10 feet for lines up to 50 kV, with greater clearance for higher voltage. Contact with overhead lines is a leading electrocution cause for crane and aerial-lift work.

Question 31

What is an Assured Equipment Grounding Conductor Program?

Accepted Answer

An alternative to GFCIs in which a competent person inspects and tests all cord sets, receptacles, and plug-connected equipment on a set schedule, recording results. It verifies the equipment grounding path is intact so a fault returns safely to ground.

Question 32

Silica permissible exposure limit on construction sites

Accepted Answer

Under 1926.1153, the PEL for respirable crystalline silica is 50 micrograms per cubic meter as an 8-hour TWA, with an action level of 25. Silica dust from cutting concrete, brick, or stone causes silicosis, lung cancer, and kidney disease.

Question 33

What is the silica standard's Table 1?

Accepted Answer

Table 1 lists specified construction tasks with matched engineering controls (water/wet methods or vacuum dust collection) and respirator requirements. Following Table 1 fully lets an employer skip individual air monitoring for that task.

Question 34

What does a PEL represent?

Accepted Answer

A Permissible Exposure Limit is the maximum legal airborne concentration of a substance a worker may be exposed to, usually as an 8-hour time-weighted average. Exceeding it triggers controls, monitoring, and sometimes medical surveillance.

Question 35

Action level vs. permissible exposure limit

Accepted Answer

The action level is a lower concentration (often half the PEL) that triggers requirements like exposure monitoring, training, and medical surveillance, before the legal limit is reached. It is an early-warning threshold designed to keep exposures from climbing to the PEL.

Question 36

When does construction noise require a hearing conservation program?

Accepted Answer

When the 8-hour time-weighted average noise exposure reaches 85 dBA (the action level), employers must provide audiometric testing, hearing protection, and training. Feasible engineering or administrative controls are required when exposure exceeds 90 dBA.

Question 37

Heat illness: heat exhaustion vs. heat stroke

Accepted Answer

Heat exhaustion brings heavy sweating, weakness, and nausea, and is treated with rest, shade, and fluids. Heat stroke is a medical emergency: hot dry skin or confusion, high body temperature, and possible collapse. Call 911 and cool the worker immediately; it can be fatal.

Question 38

What is a fit test for respirators?

Accepted Answer

A test (qualitative or quantitative) confirming a tight-fitting respirator seals to a specific worker's face. It is required before first use and at least annually. Facial hair at the seal makes a fit test fail, so a respirator cannot be relied upon.

Question 39

What is a permit-required confined space?

Accepted Answer

A confined space, limited entry/exit and not designed for continuous occupancy, that also has at least one of: hazardous atmosphere, engulfment potential, an inwardly converging shape, or any other serious hazard. Construction confined space is covered by 1926 Subpart AA.

Question 40

Safe oxygen range in a confined space

Accepted Answer

About 19.5% to 23.5% oxygen. Below 19.5% is oxygen-deficient; above 23.5% is oxygen-enriched and dangerously raises fire risk. Atmosphere must be tested before and during entry in the order: oxygen, then flammables, then toxics.

Question 41

What is a hot work permit?

Accepted Answer

An authorization, required before welding, cutting, grinding, or other spark-producing work, that confirms the area is cleared of combustibles, a fire watch is posted, and extinguishers are ready. The fire watch typically stays for at least 30 minutes after work ends.

Question 42

The PASS technique for a fire extinguisher

Accepted Answer

Pull the pin, Aim at the base of the fire, Squeeze the handle, and Sweep side to side. Aiming at the flames instead of the fuel base wastes the agent. Use an extinguisher only on a small, contained fire with a clear escape path behind you.

Question 43

What must an Emergency Action Plan cover?

Accepted Answer

Procedures for reporting emergencies, evacuation routes and exits, accounting for all personnel after evacuation, rescue and medical duties, and an alarm system. On a changing construction site, routes and muster points must be updated as the work progresses.

Question 44

Crane operations: what does the qualified rigger handle?

Accepted Answer

A qualified rigger selects and inspects slings and hardware, determines load weight and center of gravity, and rigs the load so it lifts level and secure. Rigging must be inspected before each shift; damaged slings are removed from service immediately.

Question 45

Why keep workers out of the crane swing radius?

Accepted Answer

The rotating superstructure (counterweight and boom) can crush a worker against a fixed object, a caught-between hazard. The swing radius must be barricaded so no one can enter the area where the crane body rotates.

Question 46

What is a JHA / Job Hazard Analysis?

Accepted Answer

A method that breaks a task into steps, identifies the hazard in each step, and defines a control for it before work starts. In construction it is often called an AHA (Activity Hazard Analysis) and is reviewed with the crew during the pre-task briefing.

Question 47

Why use root cause analysis after an incident?

Accepted Answer

It finds the underlying system failures (training gaps, missing guards, poor procedures) rather than blaming the worker. Asking 'why' repeatedly past the immediate cause prevents recurrence; stopping at 'employee error' leaves the real hazard in place.

Question 48

Which injuries are recordable on the OSHA 300 Log?

Accepted Answer

Work-related injuries and illnesses beyond first aid: any death, days away from work, restricted duty or job transfer, medical treatment beyond first aid, or loss of consciousness. Simple first-aid cases are not recordable.

Question 49

What is a leading vs. lagging safety indicator?

Accepted Answer

Lagging indicators measure failures after the fact (injury rates, lost-time incidents). Leading indicators are proactive measures (inspections completed, near-miss reports, training hours) that predict and prevent incidents. Strong programs track both.

Question 50

Why are toolbox talks effective for supervisors?

Accepted Answer

Short, frequent, jobsite-specific safety briefings reinforce hazard awareness for the day's actual tasks and conditions, give workers a chance to raise concerns, and build engagement. Consistency and crew participation matter more than length.

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