Class Notes - Year 4 - 2020-2021
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Year 4

Lesson 401

Energized Electrical Work Relative to NFPA 70E

Understanding the NEC

IEC Manual 401

Energized electrical work

Requires energized electrical work permit
NFPA 70E not mandatory with regard to OSHA, but is considered standard
OSHA will enforce NFPA 70E
Examples of tasks considered to be energized work
NFPA 70E 130.7(C)(15)(a) (AC current)
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NFPA 70E 130.7(C)(15)(b) (DC current)
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Permit not required if:

Troubleshooting
Voltage testing
Other diagnostic activities

Justifying Energized Work

Greater hazard to de-energize
Life support
Emergency alarms
Haz loc ventilation
Infeasible to de-energize
Testing
Part of continuous process
Less than 50V

Energized Electrical Work Permits

Example from NFPA 70E Annex J
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Flow Chart
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Includes:
Description of equipment/circuits
Justification
Safe work practices
Results of electrical hazard analysis*
Nominal voltage
Approach boundaries
Proper PPE
Arc flash boundary
Arc rated clothing and equipment
Arc flash boundaries
PPE required
Steps used to restrict others
Completed job briefing
Signature of supervisors
Rule of thumb - tool in hand = energized electrical work, Test instrument in hand = testing

Clearance and approach distances

130.4(D)(a) - (AC)
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130.4(D)(b) - (DC)
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Each boundary viewed as sphere
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Based on phase to phase volts
Measured by distance from energized part
Boundaries & Spaces
Arc flash boundary
Distance for 2nd degree burns
Limited approach boundary
Closest distance an unqualified person may approach
Limited space
Unqualified person may enter if:
Advised of hazards
Continuously escorted by qualified person
Both must wear PPE
Restricted approach boundary
Under no circumstances may unqualified person cross
Only qualified persons may cross
QP must meet one of these conditions
Circuits or equipment is insulated
Must wear PPE
Person is insulated by bucket truck or other means
Restricted space
Prohibited approach boundary
Prohibited space

Arc flash hazard analysis

Determines:
Potential electrical arc flash hazards
Arc flash boundary
Incident energy exposure
Required PPE
Should also account for type, max clearing time, and maintenance of OCPDs
Must be updated if system changes
Must take place every five years
Labeling
Example
Shows:
Available incident energy
Corresponding Minimum arc rating of clothing
Required level of PPE
Highest hazard/risk category
Nominal voltage
Arc flash boundary
Alternative
NFPA70E 130.7(C)(15)(a) - (AC)
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NFPA70E 130.7(C)(15)(b) - (DC)
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NFPA70E 130.7(C)(15)(c) - (PPE)
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PPE
If designed to protect against arc hazard, will be arc rated
Arc thermal protective value (ATPV)
Incident energy that results in 2nd degree burns
PPE classifications
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Inspecting PPE
Gloves
Last test within 6 months
Color codes
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Field tested before each use
Visual and air
Leather protection gloves over rubber gloves
Mats or blankets
Last test within 12 months
Hard hats
Manufactured within five years
Rated as:
Class G (general, rated up to 2,200V)
Class E (electrical, rated for up to 20,000V)
Eye protection
Inspect for excessive scratches
Ensure proper rating - contact manufacturer if not listed
Protective clothing
Loose fit, but not too loose
Be mindful of normal clothing worn under protective clothing
Small amount of elastic is OK
Labels should state:
Meets NFPA 70E and ASTM 1506
Arc rating in calories/cm2
Name of manufacturer
Type of fabric
Guidelines for Common Electrical Tasks
Refer to 130.7(C)(15)(a), (b), and (c)
Removing and inserting low or medium voltage drawout-type circuit breakers
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Troubleshooting
120V or less
Gloves
240V or less
PPE rated for HRC-1
240V to 600V
PPE rated HRC-2
Testing for absence of voltage
Circuit not considered de-energized until absence of voltage is verified
Same requirements as above, until verified


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