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Module 3. Evaluating Electrical Risk Factors. Evaluate. Recognize. Control. Module Objectives. Recognize the purpose and various methods for evaluating arc flash. Identify arc flash approach boundaries and their meaning. List the steps for conducting a task analysis. Module Objectives.
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Module 3 Evaluating Electrical Risk Factors
Evaluate Recognize Control
Module Objectives • Recognize the purpose and various methods for evaluating arc flash. • Identify arc flash approach boundaries and their meaning. • List the steps for conducting a task analysis.
Module Objectives • Recognize how to conduct a fall hazard evaluation. • Given a case study, analyze the hazards and recommend improvements.
Desired Outputs for Analyses • To determine flash protection boundaries • To determine incident energy • To determine the hazard/risk category for PPE selection
Dc = [2.65 X MVAbf X t]1/2 Methods for Evaluating Arc Flash NFPA 70E Equations and Tables IEEE Standard 1584 Software Programs Electrical System Analysis
Limits of Approach Exposed Energized Part Prohibited Approach Boundary Flash Protection Boundary Restricted Approach Boundary Limited Approach Boundary Note that the outer boundary is for flash protection. All other boundaries are for shock protection.
Flash Protection Zone • Outer zone of flash protection • Employees in this zone must wear flash protective equipment
Limited Approach Zone • Only qualified people can enter this zone. • Must wear flash protective equipment • Unqualified workers prohibited
Restricted Approach Zone • A person in this zone is in restricted space • Qualified people only • Approved written plan required • PPE required • Must keep as much of body out of restricted zone as possible • No body part may cross prohibited line
Prohibited Approach Zone • Being in this zone is the same as being in contact with the live part • Qualified people only • Must have specified training • Approved written plan and risk hazard analysis • PPE for working on live parts required
Using the NFPA Tables Panelboards rated 240v and below Task Hazard/Risk V-Rated V-Rated Category Gloves Tools Circuit breaker (CB) or fused switch operation with covers on 0 N N Work on energized parts, including voltage testing 1 Y Y Remove or install circuit breakers or fused switches 1 Y Y When you use this table, ALL corresponding notes must be taken into consideration.
Using the NFPA Tables 600v Class Motor Control Centers Task Hazard/Risk V-Rated V-Rated Category Gloves Tools Work on energized parts, including voltage testing 2* Y Y Insertion or removal of individual starter “buckets” from the motor control center 3 Y N Application of safety grounds, after voltage test 3 Y N *A double-layer switching hood and hearing protection are required for this task in addition to other Category 2 requirements. Note: When you use this table, ALL corresponding notes must be taken into consideration.
Steps for Task Analysis • Involve everyone who will work on the job/project. • Identify every step that must be taken to complete the job/project. • For each step, identify the electrical procedures that will be performed.
Steps for Task Analysis • Obtain or create drawings and other documents pertaining to the electrical system(s) that will be involved. • Identify the hazards associated with the job/project.
Steps for Task Analysis • Agree on safety procedures that everyone will follow. • Determine the proper tools that need to be used for the job/project. • Determine the PPE that must be used for the job/project.
Fall Hazards Why is it important to consider falls when evaluating electrical safety?
Case Study • What hazards were present in this situation? • What did the management and employees do wrong? • How could an incident like this have been prevented?