PROTECTING AGAINST ARC FLASH HAZARDS Presented by: Andrew J. Fitzpatrick, P.E.
Electricity Simply stated electricity is the flow of electrons Electricity is governed by laws: Ohms Law : V=IR Kirchoff s Law: Total Voltage around a closed loop must be equal to zero Electricity is predictable Electricity is a potential hazard
What is Electrical Safety? OSHA 1910 Subpart S Addresses electrical safety requirements for safeguarding of employees in the workplace NFPA 70E The standard defining safe work practices to protect personnel from electrical hazards 2015 NFPA Report Last 20 years has seen a dramatic decrease of fatal electrical injuries, non-fatal is not as consistent, recent trend is decreasing OSHA investigations found majority of injuries due to inappropriate work on energized equipment
Electrical Safety Engineers Perspective Employer is responsible for providing PPE used to comply with OSHA requirements. All electrical systems greater than 50V NFPA 70E defines two methods of selecting PPE Incident energy analysis (IEEE 1584 equations) Arc Flash PPE Categories Accurate Data, data collection and understanding of electrical distribution systems paramount to accurate assessments
IEEE 1584 Empirical Method based on testing in certified test laboratories Voltages from 208V 15kV (Lee Method available above 15kV) 50 or 60Hz systems Bolted Fault Current from 700A 106,000A Different grounding types, ungrounded Different enclosure types and protective devices Use computer based software: Easypower SKM ETAP
IEEE 1584 Con t Two (2) main components: Ia = arcing current (based on bolted fault current with adjustments) t = time (in seconds) arcing time A reduction of Ia or t will decrease incident energy levels Arc Current Modify service transformer characteristics (increased impedance, reduced size) Add resistance
IEEE 1584 Con t Protection Scheme changes to reduce time Current limiting fuses (selected appropriately) Adjustable type circuit breakers (LSIG) Reduced Energy Maintenance Mode Circuit Breakers Zone Interlocking Relays - Differential protection Relays Optical Add protection devices to system (i.e. main ahead of main)
High Incident Energy Level Examples Small distribution systems (Pump Stations, Wells, etc) Low utility fault current Protection devices not adjustable (MCCB Thermal-Magnetic, fuses) Service sizes mismatched with utility transformers Utility Fuses Large distribution systems (Treatment Plants) High utility fault current Device Coordination Emergency Power Scenarios
Preferred Method of Protection: De-energize It is now an industry standard to de-energize live parts, whenever possible, before an employee works on or near them.
If you Cannot De-energize Employees are permitted to work on or near exposed live parts only if they are qualified and it can be demonstrated that de-energization introduces additional or increased hazards or is infeasible due to equipment design or operational limitations.
What are Exposed Live Parts? that could be inadvertently touched or approached
Electrically Safe Work Condition Infeasible: not capable of being carried out or put in practice Inconvenient: not suited to your comfort, purpose or needs Examples: Interruption of life support equipment Deactivation of emergency alarm systems Shutdown of hazardous location ventilation equipment Examples: Financial In a hurry I know what I m doing. Want to serve client
Hierarchy of Hazard Control Most effective How do we want to control the hazards? Engineering Controls Move/add switches, meters, or phase loss monitors Administrative Controls Change of operation; do it a different way; training PPE Last resort Least effective
Qualified vs. Unqualified Qualified Person One who has skills and knowledge related to the construction, installation, maintenance and operation of the electrical equipment and installations and has received safety training on the hazards involved. o Ability to distinguish exposed live parts from other parts of electrical equipment o Ability to determine nominal voltage of exposed live parts o Knowledge of clearance distances o Familiar with proper use of special precautionary techniques, PPE, and tools Can be qualified for certain tasks and not for others
What this training qualifies you to do Work around or near live exposed parts: e.g., Accessing a live panel Work on live exposed parts: Use a voltage meter (including verification of de-energized state)
Really? I have to be qualified to do LOTO?
Electrical Safety Training Includes: Basics of electricity Basic requirements of NFPA 70E and NEC Recognizing common electrical hazards Distinguishing exposed live parts from other electrical equipment Determining nominal voltage of exposed live parts Clearance distances for working on/near exposed live parts Safe work practices and PPE Ability to determine the extent of the hazard How to release victims from contact with live circuits Methods of first aid Recognizing electrical tasks that you are not permitted to perform
Electrical Safety Program Key Components: Training Energized Electrical Work Permit PPE Risk Assessment Job Briefing Safe Work Practices Electrical Contractors Evaluation/Performance Review
Energized Electrical Work Permit (EEWP) Required when working within the restricted approach boundary Exceptions - permits not required for: Testing, troubleshooting, and voltage measuring (as long as safe work practices and PPE are used) Thermography and visual inspections (as long as restricted approach boundary will not be crossed) Be sure to know the boundaries before you start!
Alerting Techniques Safety Signs and Tags. Safety signs, safety symbols, or accident prevention tags shall be used where necessary to warn employees about electrical hazards that might endanger them. Barricades. Barricades shall be used in conjunction with safety signs where it is necessary to prevent or limit employee access to work areas containing energized conductors or circuit parts. Attendants. If signs and barricades do not provide sufficient warning and protection from electrical hazards, an attendant shall be stationed to warn and protect employees.
Reading a Label Depending on who did your study and when it was done, the labels may look a little different, but the information should be the same.
If an arc flash analysis hasn t been done.
EEWP
Personal Protective Equipment (PPE) All of these are PPE: Insulated tools Meters and testing equipment Arc-rated (AR) clothing Rubber insulating equipment (gloves, matting, blankets, sleeves..) Fall Protection Harnesses Day glow vests
Insulated Tools Must comply with IEC 900 and ASTMF 1505-94 standards. Will have the 1000 volt double triangle symbol on all rated/certified tools. Dielectrically tested with 10,000 volts, and rated for use on energized circuits up to 1000 volts.
Variety of Arc Flash PPE Shirts Fire Retardant Pants Fire Retardant Over clothing wear Arc-rated (Coveralls, or overcoat and over pants). Hardhat and face shield. Hoods Arc-rated Hearing protection Rubber gloves. Leather protectors. Cotton glove liners. Glove bag. Rain gear Arc-rated Winter wear (coats) Arc-rated Dielectric boots. Safety shoes rated EH. (Electrical Hazard- no metal fasteners) Harness Arc-rated
Typical PPE Kit PPE Category 2 arc rated clothing (min rating 8 cal/cm2) Arc rated long-sleeve shirt & pants, or arc rated coverall. Class OO, 11 high certified rubber gloves with leather protectors. Hard hat. Safety glasses or goggles Head covering (hood). Arc rated face shield with arc rated balaclava. Hearing Protection. Leather safety shoes.
When do you need to wear this? PPE Category 2 arc flash apparel This category of PPE will NOT protect you against all hazards for all tasks. It is appropriate for: Voltage testing/troubleshooting Removal of covers Verifying de-energization Providing the equipment matches or exceeds the potential hazard.
PPE: Hand Protection Rubber gloves need to have the class and voltage rating visible on the outer cuff. Wear heavy-duty leather protectors when using rubber gloves, and remember leather gloves are not voltage rated, they are only to protect the rubber. Glove liners need to be 100% cotton.
PPE: Hand Protection Store gloves in a canvas glove bag to protect against damage and UV damage and store flat (do not fold). Inspect gloves before every use for damage, which includes an inflation test. Gloves need to be dielectrically tested by a certified lab before being put into service and then every 6 months.
Hazard Risk Analysis Evaluate hazards in each step of the job and consider safety controls Same as JSA Job Safety Analysis Required whenever an electrical hazard exists
Job Briefing Required for all electrical work Must cover: Hazards Work procedures Energy source controls PPE Can be simple and verbal, or more detailed and written
When you hire Electrical Contractors Follow Established Contractor Policy: Contractor Pre-qualification Contractor Orientation, including notice of hazards Performance Evaluation Note: The meeting between owner and the electrical contractor must be documented. If imminent danger exists, STOP WORK!!!
Evaluation/Performance Review The owner is required to perform field audits to verify you are following these electrical safety requirements. So make sure you are following safe work practices and wearing your PPE when you re supposed to.
Why we need to be careful
You just don t know what is out there
THANK YOU! QUESTIONS?