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Arc Flash and NFPA 70EPresented by: J.D. Kyle
OSHA 1910.333 (a) (1)
Wearing Proper PPE?
Safe Work Practices
not to work “hot” or “live” except :1. De energizing introduces additional
or increased hazards – Emerg systems, Life Support.
2. Infeasible due to equipment design or operationallimitations - troubleshooting
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Electrical Arc
Pressure Waves
Copper Vapor:Solid to VaporExpands by67,000 times
Molten Metal
Intense Light
Hot Air-Rapid Expansion
35,000 °F
Shrapnel
Sound Waves
2012 NFPA 70 EResponsibility 105.3
Responsibility:The employer shall provide the safety related work practices and shall train the employee, who shall implement them
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110.2 (A) Safety Training
• For employees who face electrical risk that has not been de-energized. Employees shall be trained to:– Understand specific hazards associated with
electrical energy– Trained in safety related work practices– Procedural requirements– Trained to identify & understand relationship
between electrical hazards and possible injury
110.2 (D)(1) Qualified Person
Qualified Person- Shall be trained and knowledgeable of the construction & operation of equipment or specific work method and be trained to recognize and avoid the electrical hazards that might be present with respect to that equipment or work method.
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110.2 (D)(1) Qualified Person. Continued
(a) Such persons shall also be familiar with the proper use of special precautionary techniques
-PPE including arc flash suit-insulating and shielding material-insulated tools-and test equipmentA person can be qualified with respect to certain
equipment and methods but still be unqualified for others
110.2 (D)(1) Qualified Person. Continued
(b)(4) Decision-making process necessary to determine the degree and extend of the hazard and the ppe and job planning necessary to perform the task safely
Note: Re-training shall be performed at intervals not to exceed 3 years
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ARC Flash
• 3 Main Factors Determining an Arc Flash– Available Energy (Ka)– Distance (inches)– Time (sec) (cycles)
=Incident Energy=CAL/CM2
11 Cal FR vs. Std Cotton non FR
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25 cal/cm2 suit vs. std non FR plus non FR denim = ~5 cal
ARC FLASH ANALYSIS• An arc flash hazard analysis shall determine
the arc flash boundary, the incident energy at the working distance and the ppe people within the arc flash boundary shall use.
• Exception: The requirements of 130.7(c)(15) and 130.7(c)(16) shall be permitted in lieu of determining the incident energy at the working distance
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Table 130.7(c)(16) Protective Clothing and PPE
Hazard Risk Category (HRC)
Clothing Cal/cm2
0 Nonmelting flammable (untreated cotton, wool, rayon etc with a fabric weight of at
least 4.5 oz
Nonmelting clothing at least 4.5 oz
1 Arc-rated FR shirt and FR pants or coveralls
Minimum Arc Rating of 4
2 Arc rated FR shirt and FR pants or coveralls
Minimum arc rating of 8
3 Arc rated FR system to meets required minimum
Minimum Arc Rating of 25
4 Arc rated system meets required minimum
Minimum Arc Rating of 40
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Work Scope
• Install and verify Phase rotation on line side of a 480 Volt 60 amp Disconnect.
• Using tables determine level of ppe required
D.5 Calculation of Incident Energy for an Arc Flash Analysis
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Work Scope: Install & verify phase rotation on line side of a 480V, 60amp disconnect
480 V2500Kva
Trans-former
480V Main, 3500A
480V600A
480V600A
480V600A
13kv1200AMain3 sec fuses
Utility
480V60A
Disconnect
Determine level of PPE to perform work?
Various software that can help you conduct an Arc Flash Analysis
-Duke Flux calculator-Easy Power Calculator-Arc Advisor
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Work Scope: Install & verify phase rotation on line side of a 480V, 60amp disconnect
480 VTrans-former
480V Main, 1200A
480V600A
480V600A
480V600A
A BWhat point has higher arc flash potential? A or B
13kv1200AMain
Utility
Incident Energy
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Incident Energy
Incident Energy
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Incident Energy
24 inch Flash Hazard Boundary 3 cal/cm •2 Flash Hazard at 18 inches1… PPE Level, 1 Layer 6 oz Nomex ®,
Leather Gloves Faceshield480 VAC Shock Hazard when Cover is removed
36 inch Limited Approach12 inch Restricted Approach - 500 V Class 00 Gloves
1 inch Prohibited Approach - 500 V Class 00 Gloves
Equipment Name: Slurry Pump Starter
WARNING!Arc Flash and Shock HazardAppropriate PPE Required
Courtesy E.I. du Pont de Nemours & Co.
130.3 P25 Review the labels every 5 years or when changes or upgrades occur
Date:
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Biggest cause of Death and Burns
Human Error98%
22.6 KA SymmetricalAvailable Fault Current
@ 480V, 3 Phase
Fault Initiated on Line Side of 30A Fuse
30A RK-1Current Limiting Fuse
Size 1 Starter
Test No. 46 cycle STD640A OCPDNon Current Limitingwith Short Time Delay
Set @ 6 cycle opening
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Arc Flash
> Indicates Meter Pegged
Results: Test No.4
SoundSound141.5 db @ 2 ft.
T2T2>225°C / 437°F
T3T350°C / 122°F
P1P1>2160 lbs/sq.ft
> 225°C / 437°F
T1T1
4.3 cal/cm² @ 18”
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22.6 KA SymmetricalAvailable Fault Current
@ 480V, 3 Phase
Fault Initiated on Line Side of 30A Fuse
30A RK-1Current Limiting Fuse
Size 1 Starter
Test No. 3601A.Class LCurrent Limiting FuseThis type of OCPD has a let through of 11KA and clears in ½ cycle
Arc Flash
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> Indicates Meter Pegged
SoundSound133 db @ 2 ft.
T2T262°C / 143.6°F
T3T3(No Change
From Ambient)
P1P1504 lbs/sq.ft
> 175°C / 347°F
T1T1
Results: Test No.3 = 0.33 cal/cm² @ 18” 1.74 cal/cm² @ 6”
Biggest cause of Death and Burns
Human Error98%
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TURN THE POWER OFF• Work out ways to de energize• Not the dinosaur method to work on or around
it energized• NO POWER = NO ARC FLASH or NO SHOCK• This is the easiest, quickest and safest• Challenge owners or contractors that push to do
it energized
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