©2008 3-1 evaluating electrical risk factors module 3

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Evaluating Electrical Risk Factors

Module 3

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Evaluate

Control

Recognize

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Module Objectives

List the steps for conducting a task analysis.

Recognize the purpose and various methods for evaluating arc flash.

Identify arc flash approach boundaries and their meaning.

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Module Objectives

Given a case study, analyze the hazards and recommend improvements.

Recognize how to conduct a fall hazard evaluation.

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1. To determine flash protection boundaries

2. To determine incident energy3. To determine the hazard/risk

category for PPE selection

Desired Outputs for Analyses

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NFPA 70E Equations and Tables

Methods for Evaluating Arc Flash

IEEE Standard 1584Software Programs

Dc = [2.65 X MVAbf X t]1/2

Electrical System Analysis

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Exposed Energized Part

Prohibited Approach BoundaryFlash Protection Boundary

Restricted Approach Boundary Limited Approach Boundary

Limits of Approach

Note that the outer boundary is for flash protection. All other boundaries are for shock protection.

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Flash Protection Zone

Outer zone of flash protection

Employees in this zone must wear flash protective equipment

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Limited Approach Zone

Only qualified people can enter this zone.Must wear flash protective equipmentUnqualified workers prohibited

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Restricted Approach Zone

A person in this zone is in restricted spaceQualified people onlyApproved written plan requiredPPE requiredMust keep as much of body out of restricted zone as possibleNo body part may cross prohibited line

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Prohibited Approach ZoneBeing in this zone is the same as being in contact with the live partQualified people onlyMust have specified training Approved written plan and risk hazard analysisPPE for working on live parts required

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Using the NFPA Tables

Task Hazard/Risk V-Rated V-Rated Category Gloves Tools

Circuit breaker (CB) orfused switch operationwith covers on 0 N NWork on energized parts,including voltage testing 1 Y YRemove or install circuitbreakers or fused switches 1 Y Y

Panelboards rated 240v and below

When you use this table, ALL corresponding notes must be taken into consideration.

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Using the NFPA Tables

Task Hazard/Risk V-Rated V-Rated Category Gloves Tools

Work on energized parts,including voltage testing 2* Y YInsertion or removal ofindividual starter “buckets”from the motor controlcenter 3 Y NApplication of safetygrounds, after voltage test 3 Y N

600v Class Motor Control Centers

*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.

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1. Involve everyone who will work on the job/project.

2. Identify every step that must be taken to complete the job/project.

3. For each step, identify the electrical procedures that will be performed.

Steps for Task Analysis

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Steps for Task Analysis

4. Obtain or create drawings and other documents pertaining to the electrical system(s) that will be involved.

5. Identify the hazards associated with the job/project.

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Steps for Task Analysis6. Agree on safety procedures that

everyone will follow.

7. Determine the proper tools that need to be used for the job/project.

8. Determine the PPE that must be used for the job/project.

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What hazards were present in this situation?

What did the management and employees do wrong?

How could an incident like this have been prevented?

Case Study

©2008 3-1 evaluating electrical risk factors module 3

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