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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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