1. Electrical Safety: Are you Prepared?
L. Rene’ Graves, BS, CSP
Senior Safety Specialist
Texas Instruments, Inc.
Dallas, TX

2. L. Rene’ Graves, BS, CSP Certified Safety Professional
BS in Occupational Safety and Health from Murray State University
AS in Industrial Electronics
AS in Air Conditioning and Refrigeration
Journeyman Electrician in the State of Texas
Member Group Technical Staff
Member of Texas Instruments, Inc. WW-ESH team

3. Conclusion Stop Electrical Events from occurring by:
Identifying what causes these events
Conducting a risk assessment through the use of an electrical energy study
Creating a plan to reduce identified risks before an event occurs
Implementing a plan
Consider participation in the IEEE Electrical Safety Workshop to learn more about electrical safety

4. Overview Financial Burden of electrical work
Components of an electrical event
NFPA 70E
Electrical System Equipment
Investigation Method

5. Financial Burden
OSHA identified the following areas in electrical safety in which fines were assessed:
Wiring design and protection
Wiring methods, components and equipment for general use
Training
Failure to provide a safe work environment
Financially the industries were cited
General Industry - $1,373,087
Construction – $1,133,424

6. Components of an Electrical Event
OHM’s Law
Shock
Arc and Arc Flash
Blast Energy
Incident Energy
Hazard Boundary
Burns

7. Ohm's Law E = I * R or Volts = Current * Resistance
Volts (potential difference)
Current (ampere)
Resistance (impedance)

8. Shock
Shock – a reflex response to the passage of electric current through the body.
Effect of Electrical Current flowing through the Body
Men
Women
Slight tingling sensation felt
0.4 ma
0.3 ma
Threshold of perception
1.1 ma
0.7 ma
Painful but able to release from electrical source
9.0 ma
6.0 ma
Painful and unable to release from electrical source
16 ma
10.5 ma
Severe pain and difficulty breathing
23 ma
15.0 ma
Possible heart fibrillation after 3 seconds
100 ma

9. Arc and Arc Flash Arc and Arc Flash
An arc is an electrical current bridging an air gap
Most common manmade creations of an arc occur during a welding procedure
Temperatures of an arc flash can reach up to 35,000°F and usually vaporize any material when extended contact occurs
Besides heat; light, sound, and UV radiation are released by an arc
The flash of light and other radiation produced by an arc is called an “arc flash”

10. Examples of Arc Flash
Box or Enclosed
Open Air

11. Blast Energy
Blast Energy or Pressure – the amount of force produced from rapidly expanding air during an electrical event
Blast pressure waves have thrown workers across rooms and knocked them off ladders. Pressure on the chest can be higher than 2000 lbs/ sq. ft.
These high pressures can easily exceed the ability of a worker to withstand the force causing a worker to be knocked off a ladder, or rupturing eardrums, and possibly causing the lungs to collapse
Calculating potential blast effect

12. Blast Calculation
225 KVA Transformer, 3 phase, 480V to 208/120V with Z = 3.5% Impedance
Distance (D) - 18” from source (NFPA 70E Box)
Current (I – (KVA) – KVA

13. Incident Energy
The amount of energy imposed on a surface, at a certain distance from the source, generated during an electrical arc event
The unit of measurement is either calories per centimeter squared (cal/cm2) or joules per centimeter squared (J/cm2)

14. Hazard Boundary Hazard Boundary Flash Protection Boundary
Limited Approach Boundary
Restricted Approach Boundary
Prohibited Approach Boundary
Prohibited Space

15. Burns
Burns – any energy caused by heat, electricity, chemicals, radiation or gases.
Burn Classification
1° Burn – redness to the outer layer of the skin only. Healing time is normally 6-10 days
2° Burn – superficial, no loss of dermis. Healing time 7-14 days
3° Burn - deep dermal burn, whole skin loss. Healing more than 21 days. (Note: large areas where healing might not occur and debriefing will be required)
4° Burn – deep structural loss. Healing – never if area is large

16. Temperature as it Effects the Human
Burns and the Effects of Temperature on Human Skin
Skin Temperature
Time to reach temperature
Damaged Caused
110°F
6.0 hours
Cell breakdown begins
Possible 1-degree burn
158°F
1.0 seconds
Total cell destruction
1st-degree burn / begin 2nd-degree burn
176°F
0.1 seconds
6 cycles
2nd-degree burn
200°F
3rd-degree burn

17. Questions about: Shock, Arc, or Blast

18. Limitations of NFPA 70E
Using table method (NFPA 130.2(C)) to establish level of PPE
(d) For systems rated less than 1000 volts, the fault currents and upstream protective device clearing times are based on an 18 in. working distance. 
(e) For systems rated 1 kV and greater, the Hazard/Risk Categories are based on a 36 in. working distance. 
(f) For equipment protected by upstream current limiting fuses with arcing fault current in their current limiting range ( cycle fault clearing time or less), the hazard/risk category required may be reduced by one number. 

19. Limitations of NFPA 70E (cont.)
Specific Notes (as referenced in the table): 
1. Maximum of 25 kA short circuit current available; maximum of 0.03 sec (2 cycle) fault clearing time. 
2. Maximum of 65 kA short circuit current available; maximum of 0.03 sec (2 cycle) fault clearing time. 
3. Maximum of 42 kA short circuit current available; maximum of 0.33 sec (20 cycle) fault clearing time. 
4. Maximum of 35 kA short circuit current available; maximum of up to 0.5 sec (30 cycle) fault clearing time. 

20. Limitations of NFPA 70E (cont.)
Using Appendix D to Incident Energy
Calculates incident energy for 3-phase arc on systems rated 600 V and below; applies to short-circuit currents between 16 kA and 50 kA
Equations must be used only under qualified engineering supervision  

21. Arc Flash Hazard Analysis
Labeling of Equipment
Establish the Arc Flash Protection Boundary
Identify the Personal Protective Equipment
Equipment Labeling - Equipment shall be field marked with a label containing the available incident energy or required level of PPE
A review of the arc flash analysis should occur anytime major renovation is conducted or periodically, not to exceed 5 years

22. Equipment Terminology
Transmission
Distribution

23. Electrical Equipment Components
Panel Interior Or
Guts
Box or Can
Door Or
Hinged cover
Dead Front Or
Pancake

24. Electrical Events Two categories of Electrical Events
Human
Equipment
Signs of problems
Discolored metal in electrical equipment
Report of someone being shocked
Breaker tripping
Flickering of lights or power
Over heating of conductors

25. Prior to an Electrical Event
Conduct a total system evaluation
Fault Current Study
What is it?
How is the study executed?
Training Evaluation
Are the correct people being trained?
Are the employees knowledgeable of the equipment upon which they are performing maintenance?
What training do your suppliers have to make them qualified to work on your equipment?

26. Electrical Event Investigation
Securing the scene
Isolate the area
Request assistance from electrical team
Confirm the electrical panel is off
Install LOTO and verify equipment involved in the event is de-energized
Provide support for injured employees
Gather Investigation Team
Photographs

27. Final Report Contents
What information should be contained in the report?
Who is responsible for ensuring the accuracy of the report?
How do you limit the information and limit the distribution so that multiple copies stating different things are not floating around?

28. Conclusion Stop Electrical Events from occurring by:
Identifying what causes these events
Conducting a risk assessment through the use of an electrical energy study
Creating a plan to reduce identified risks before an event occurs
Implementing a plan
Consider participation in the IEEE Electrical Safety Workshop to learn more about electrical safety

29. IEEE Workshop 2011
Conference: 2011 IEEE IAS Electrical Safety Workshop
Conference Dates: 24 Jan - 28 Jan 2011
Location: Toronto Ontario

30. Electrical Safety: Are you Prepared?
L. Rene’ Graves, BS, CSP
Senior Safety Specialist
Texas Instruments, Inc.
Dallas, TX