Published on January 25, 2008
Electrical Stand-DownReview of BNL Arc-Flash Incident &Discussion of Arc-Flash Hazards RelatingTo Switch & Circuit Breaker Operations: Electrical Stand-Down Review of BNL Arc-Flash Incident & Discussion of Arc-Flash Hazards Relating To Switch & Circuit Breaker Operations John DiNicola LESC Chair Agenda: Agenda Discuss BNL arc-flash incident Discuss other DOE arc-flash incidents Arc-flash hazards and mitigation Skill-of-the-craft and work planning Answer your questions Survey Review of Friday, April 14, 2006 Incident: Review of Friday, April 14, 2006 Incident C-A engineer was operating a 480 volt, 400 amp fusible disconnect switch located in a 1,200 amp panel when the switch failed and an arc-flash occurred. The switch cover was closed and remained closed. The panel bulged and hot gasses escaped. Arc-flash ignited some paper located adjacent to the panel. Review of Friday, April 14, 2006 Incident: Review of Friday, April 14, 2006 Incident Engineer received 1st degree burns on forearms, hands and face. He also received a small patch of 2nd degree burn on one forearm. Engineer went to the hospital and was released that afternoon. There is concern over the irritation of one eye, which will receive further evaluation. Person was wearing cotton undergarments, short-sleeve cotton shirt , blue jeans, but no eye protection. Person had valid Electrical Safety I and C-A Electrical Training. Review of Friday, April 14, 2006 Incident: Review of Friday, April 14, 2006 Incident Review of Friday, April 14, 2006 Incident: Review of Friday, April 14, 2006 Incident ANL Arc-Flash In 277 Volt Switch 10/23/2005: ANL Arc-Flash In 277 Volt Switch 10/23/2005 Scientist operated an outdoor 277Volt switch to turn on lights in gas yard. Switch failed, hot gasses escaped, caused 2nd degree burn on hand. SLAC Arc-Flash Incident: SLAC Arc-Flash Incident Worker received 3rd degree burns ORNL Arc-Flash Incident 3/26/2006: ORNL Arc-Flash Incident 3/26/2006 Worker (contractor electrician) was installing ground connection to cable tray which has energized 480 Volt cable in it. Drill penetrated tray and cable insulation causing a short and resulting arc-flash. Breaker tripped to end the event Worker received “mild” burn on forearm and hand. Arc/Blast Caused Burns: Arc/Blast Caused Burns First Degree burns affect only the surface of the skin. The burned area is red and tender, much like a mild sunburn. Second Degree burns are characterized by blistering of the skin, either early or late. The complete thickness of the skin is not destroyed. This is the most painful type of burn. Third Degree burns are characterized by complete destruction of the skin with charring and cooking of the deeper tissues. These are the most serious types of burns as they produce deeper wounds. They are not as painful because the sensory nerve endings have been destroyed. Fourth Degree burns goes through all the layers of the skin and down into the muscle and the bone. It looks like a third degree burn and does great harm to the body structure. Since the nerves are burnt there is little pain in this burn. What is Proper PPE – Audience Questions: What is Proper PPE – Audience Questions What is the proper PPE for operating a 480 Volt switch with the cover closed? Would this have been adequate PPE? What does the code (NFPA 70E) say the PPE should do? Answers to Audience questions: Answers to Audience questions Operation of any switch or CB <600Volts requires Cotton undergarments Long sleeve non-melting fiber or untreated natural-fiber shirt and pants (untreated cotton, wool, rayon, or silk) Eye protection (safety glasses or goggles) PPE is designed to limit the burn to onset of second degree burn (curable) A bad sun burn Skill of the Craft: Skill of the Craft Is work planning required for skill of the craft work? Skill of the Craft – Work Planning: Skill of the Craft – Work Planning Is work planning required for skill of the craft work? STOP! Review the operation Determine the hazards Determine the hazard mitigation (PPE, techniques, etc.) Review the Operation – Read the Signs: Review the Operation – Read the Signs Review the Operation – Read the Signs: Review the Operation – Read the Signs Note – Specific Personal Protective Equipment and approach boundaries are specified* * Example is provided by a vendor. At BNL, dimensions and Personal Protective Equipment requirements are evaluated on a case-by-case basis. Review the Operation – Read the Signs: Review the Operation – Read the Signs Determine the Hazards: Determine the Hazards Exposed bus - shock hazard? Am I in the arc-flash boundary? What other hazards surround me? Trip Height Obstructions Sharp Edges Arc-Flash and Blast Hazard: Arc-Flash and Blast Hazard If equipment failure occurs, there is a potential for an arc flash. Under normal operation of circuit breakers and disconnect switches the risk of arc flash is extremely low. However, an arc flash with protective covers off is a serious, life-threatening occurrence. Arc-Flash and Blast Hazards: Arc-Flash and Blast Hazards An electric arc produces heat at 15,000oC (35,000oF), which results in extremely intense heat exposure to a person’s body and clothing. Determine the Hazards/Risks: Determine the Hazards/Risks Determine the Hazards/Risks: Determine the Hazards/Risks Hazards of Switch/CB Operation: Hazards of Switch/CB Operation 240 Volt and below Panelboards Operation of switch or circuit breaker w/covers ON Hazard/Risk Cat 0 Operation of switch or circuit breaker w/covers OFF Hazard/Risk Cat 1 > 240V to 600 Volt Panelboards Operation of switch or circuit breaker w/covers ON Hazard/Risk Cat 0 Operation of switch or circuit breaker w/covers OFF Hazard/Risk Cat 1 Determine the Hazard Mitigation: Determine the Hazard Mitigation Clothing for the Hazard/Risk Mitigation: Clothing for the Hazard/Risk Mitigation Hazard/Risk Categories “0” – Non-melting or untreated natural fiber clothing, long sleeves and pants “1” – Fire Rated (FR) clothing (heavy duty jeans permissible) “2” – Fire Rated (FR) clothing “2*” – Like “2” but with Flash hood “3” and up – Flash suits, multiple layers FR Other PPE for the Hazard/Risk Mitigation: Other PPE for the Hazard/Risk Mitigation Eye protection always required Maybe required depending on the task Hard hats Face shields Hearing protection Gloves – leather and/or voltage rated These are items that should be reviewed during your work planning (formal or skill of the craft) Minimum Personal Protective Equipment: Minimum Personal Protective Equipment The minimum PPE for operation of circuit breakers and disconnect switches (cover ON) operating at less than 600 Volts with covers on, is: Safety Glasses Non-melting or untreated natural fiber clothing such as untreated cotton, wool, rayon, or silk. Long-sleeve shirt Pants What’s wrong in this picture? Slide28: Safety Glasses Always Required! Remember in all cases these operations still require the use of safety glasses! Slide29: Proper Operation to Reduce Risk When pulling the handle on a disconnect switch or operating a circuit breaker, always consider the possibility of an arc explosion. Stand to the side and turn your face away when throwing the switch, if possible. WRONG Never stand in front of, or directly face the switch CORRECT Stand to the side of the switch and face away. Who is Responsible for Safety?: Who is Responsible for Safety? WE ARE!!!!!!!!!!!!! We look out for ourselves We look out for others We can STOP WORK!!! We are obligated to do so! Good Housekeeping: Good Housekeeping Three recent electrical incidents resulted in the ignition of combustible materials located near the equipment. The material did not need to be there! Where to Find this Presentation?: Where to Find this Presentation? http://www.bnl.gov/esh/esc/ Electrical Safety Committee Web Page Please Help Us: Please Help Us A short anonymous survey is being handed out to help us evaluate the effectiveness of past training Side 1 – For workers who have taken Electrical Safety I training. ( The longer survey) Side 2 – All others Survey is simple Y or N with possibility for free form comments at the end. Please hand in as you leave!