IEC Electrical Safety Practices 4

Question 1

Which type of fire extinguisher is appropriate for use on an energized electrical fire?

Accepted Answer

Class C (CO2, dry chemical, or halon)

Answer

Class C extinguishers use non-conductive agents such as CO2, dry chemical, or halon, making them safe for use on energized electrical fires.

Question 2

What is the purpose of a Job Hazard Analysis (JHA) before beginning electrical work?

Accepted Answer

To systematically identify hazards associated with each task step and implement controls before work begins

Answer

A JHA breaks each task into steps, identifies potential hazards at each step, and establishes controls to eliminate or reduce those hazards before work starts.

Question 3

What is 'step potential' and why is it dangerous near downed power lines?

Accepted Answer

A voltage gradient in the ground that can drive current through a person's legs when stepping

Answer

Step potential is a voltage gradient in the ground near a fault point; current can flow through a person's legs when one foot is at a higher potential than the other.

Question 4

Under OSHA 29 CFR 1910.147, which energy source type is NOT covered by the Lockout/Tagout standard?

Accepted Answer

Hot water systems under normal household pressure below OSHA's scope threshold

Answer

OSHA 1910.147 covers electrical, mechanical, hydraulic, pneumatic, chemical, thermal, and gravitational energy; however, small residential systems below threshold are outside its industrial scope.

Question 5

What is the function of a Ground Fault Circuit Interrupter (GFCI) in electrical safety?

Accepted Answer

Interrupts power when it detects a current imbalance of 5 milliamps or more between line and neutral

Answer

A GFCI monitors the current difference between line and neutral and trips within milliseconds when an imbalance of approximately 5 mA is detected, preventing electrocution.

IEC - Independent Electrical Contractors Practice Test

IEC - Independent Electrical Contractors Practice Test

IEC Electrical Safety Practices 4