CHST General 4

Question 1

A competent person classifies the soil in a 10-foot-deep trench as Type A. The trench will be open for only 18 hours. Under OSHA 1926 Subpart P, Appendix B, what is the steepest maximum allowable slope for this short-term excavation?

Accepted Answer

1/2H:1V (63°)

Answer

Appendix B normally limits Type A soil to 3/4H:1V (53°). There is one exception: a simple slope excavation in Type A soil that is 12 feet deep or less and open 24 hours or less (short-term) may be sloped at 1/2H:1V (63°). This trench is 10 feet deep and open for 18 hours, so it qualifies. 1H:1V is the limit for Type B soil. Vertical sides without protection are only allowed in stable rock or in excavations under 5 feet deep.

Question 2

A construction employee's annual audiogram shows a Standard Threshold Shift (STS) in the left ear. For the injury to be recorded on the OSHA 300 Log as a hearing loss case, what additional condition must be met?

Accepted Answer

The employee's total hearing level in that same ear must be 25 dB or more above audiometric zero, averaged at 2000, 3000, and 4000 Hz

Answer

Under 29 CFR 1904.10, a case is recordable only when both conditions are met in the same ear: (1) an STS, meaning an average change of 10 dB or more at 2000, 3000, and 4000 Hz compared with the baseline, and (2) a total hearing level of 25 dB or more above audiometric zero, averaged at the same frequencies. The employer may retest within 30 days, not 7. An STS in one ear is enough; both ears are not required.

Question 3

A mobile crane will operate near an overhead power line rated at 230 kV. The utility has confirmed the voltage, and the employer uses Table A of 29 CFR 1926.1408. What is the minimum clearance distance that must be kept from the line?

Accepted Answer

20 feet

Answer

Table A in 1926.1408 sets these minimum clearances: up to 50 kV = 10 ft; over 50 to 200 kV = 15 ft; over 200 to 350 kV = 20 ft; over 350 to 500 kV = 25 ft. A 230 kV line falls in the 200–350 kV band, so 20 feet applies. 50 feet is the default distance when the voltage is unknown and over 350 kV, or when the employer does not use Table A for lines over 350 kV. It does not apply to a confirmed 230 kV line.

Question 4

A rebar worker is tied off on a vertical wall using a positioning device system, not a personal fall arrest system. Under 29 CFR 1926.502(e), which requirement applies specifically to positioning device systems?

Accepted Answer

It must be rigged so the employee cannot free fall more than 2 feet, and anchorages must support at least twice the potential impact load or 3,000 lb, whichever is greater

Answer

1926.502(e) requires positioning device systems to be rigged so the employee cannot free fall more than 2 feet. Anchorages must support at least twice the potential impact load of the employee's fall, or 3,000 lb, whichever is greater. The 6-ft free fall limit, 5,000-lb anchorage, 1,800-lb maximum arresting force, and 3.5-ft deceleration distance are all personal fall arrest system requirements. That makes them tempting distractors.

Question 5

Per 29 CFR 1926.451, each suspension rope on a two-point adjustable suspension scaffold, including its connecting hardware, must be able to support at least how much?

Accepted Answer

6 times the maximum intended load applied or transmitted to that rope

Answer

1926.451(a)(4) requires each suspension rope, including connecting hardware, to support at least 6 times the maximum intended load applied or transmitted to that rope. The 4-times factor in 1926.451(a)(1) applies to the scaffold itself and its components, not to suspension ropes. A related rule for stall-capacity hoists requires the rope to resist at least 2 times the stall load of the hoist. That is a different requirement from the one in this question.

CHST - Construction Health and Safety Technician Practice Test

CHST - Construction Health and Safety Technician Practice Test

CHST General 4