Electrical Safety Flashcards

According to OSHA, which of the following is NOT an acceptable method to protect employees from electrical shock when working near overhead power lines?

Answer: Relying solely on verbal warnings from a spotter without any physical barriers

Verbal warnings alone do not constitute an adequate protective measure; OSHA requires physical means such as barriers, minimum clearance distances, or de-energization.

The 'touch potential' in electrical safety refers to:

Answer: The voltage between an energized object being touched and the ground beneath the worker's feet

Touch potential is the voltage difference between an energized surface that a person touches and the ground where they stand, which drives shock current through the body.

When applying NFPA 70E's incident energy analysis method, the two critical inputs needed to determine incident energy are:

Answer: Available fault current and arcing duration (clearing time of overcurrent protective device)

Incident energy calculations require knowledge of the available fault current (which determines arc magnitude) and the arcing duration (determined by protective device clearing time).

Under OSHA 29 CFR 1910.303, electrical equipment must be installed and maintained in a manner that:

Answer: Examines and uses equipment listed or labeled by a nationally recognized testing laboratory (NRTL)

OSHA requires that electrical equipment be listed or labeled by an NRTL (such as UL or ETL) as evidence that it meets recognized safety standards.

A safety professional discovers that workers are using extension cords as permanent wiring. This practice is hazardous primarily because:

Answer: Extension cords lack the overcurrent protection and physical protection required of permanent wiring

Extension cords are not designed for permanent use; they lack conduit protection, proper strain relief, and built-in overcurrent protection required by the NEC for fixed wiring.

The resistance of the human body used in standard electrical safety calculations is typically assumed to be:

Answer: 500 to 1,000 ohms for skin-to-skin contact under typical conditions

Standard electrical safety calculations typically assume 500–1,000 ohms of body resistance for skin contact under general workplace conditions, though wet skin can reduce this significantly.

Which of the following best describes the purpose of equipment grounding in electrical systems?

Answer: To provide a low-resistance fault current path that causes overcurrent devices to trip and clear the fault

Equipment grounding ensures that a fault to metal enclosures creates a low-impedance path back to the source, causing the overcurrent protective device to trip and remove the shock hazard.