Electrical Safety in the Workplace FN000385/CR

FN000385/CR, Electrical Safety in the Workplace 2 Overview NFPA 70E Objectives Electrical Hazards Mitigation of Hazards Electrical Work Activities –Diagnostic vs. Manipulative

FN000385/CR, Electrical Safety in the Workplace 3 Overview Fermilab Electrical Safety Policy Electrical Hazard Analysis –Shock Hazard Analysis –Arc Flash Hazard Analysis Establishing an Electrically Safe Work Condition Additional Resources

FN000385/CR, Electrical Safety in the Workplace 4 NFPA 70E Objectives Protect workers from electrical shock and arc-flash hazards Understand the work and associated electrical hazards Understand the PPE requirements for electrical shock protection and arc-flash protection

FN000385/CR, Electrical Safety in the Workplace 5 Electrical Hazards Three Main Hazards –Electric Shock –Arc-Flash –Arc Blast

FN000385/CR, Electrical Safety in the Workplace 66 Electrical Hazards Electric Shock –Electric current passes through the body –1 milliamp can feel the current –15 milliamps can’t let go of electrical source –100 milliamps through chest can result in ventricular fibrillation which is usually fatal –Automatic External Defibrillator (AED) only practical way to return heart to normal rhythm –Deep tissue burns FN000385/CR, Electrical Safety in the Workplace

7 Electrical Hazards Arc Flash –Electric current passes through air, between a “Hot” conductor and ground, or between “Hot” conductors –Severity is determined by Available fault current Conductor size Time or duration –Temperatures can reach 35,000 Degrees F roughly three times the surface temperature of the sun

FN000385/CR, Electrical Safety in the Workplace 8 Electrical Hazards Arc Flash –Clothing or PPE that burns and melts to the body is the most serious concern –203 Degrees F for 0.1 seconds results in third degree burn –The incident energy threshold for the onset of a second degree burn is 1.2 cal/cm 2. –Exposure can easily cause skin burns and ignite clothing

FN000385/CR, Electrical Safety in the Workplace 9 Electrical Hazards Arc Blast –Rapid expansion of air caused by an electrical arc Caused by two sources –Metal boiling and vaporizing –Heating of air from the arc Copper expands by a factor of 67,000 times when vaporized Best categorized as an explosion –Hearing loss due to blast explosion –Lacerations/Punctures from blast debris –Trauma from percussion force

FN000385/CR, Electrical Safety in the Workplace 10 Electrical Hazards 1997 F0 Compressor Room 480 volt MCC Arc Flash Event

FN000385/CR, Electrical Safety in the Workplace 11 Mitigation of Hazards Arc Blast –Work De-Energized –Engineer Out the Hazard –Follow Safe Work Practices Electrical Hazard Analysis Employ Lockout/Tagout of Hazardous Electrical Energy Sources Use Voltage Insulating PPE and Equipment Use PPE for Arc-Flash Protection Use Ground Fault Circuit Interrupters

FN000385/CR, Electrical Safety in the Workplace 12 Diagnostic vs. Manipulative Work Diagnostic –Inspection, testing, voltage and/or current measurements, phase alignment, troubleshooting, circuit and signal tracing, thermal imaging, etc. that are performed on or near exposed live parts within the Limited Approach Boundary –Verification Associated with LOTO –Performed by Qualified Persons utilizing appropriately rated measurement equipment and required PPE.

FN000385/CR, Electrical Safety in the Workplace 13 Diagnostic vs. Manipulative Work Manipulative –Making, tightening or breaking of energized electrical connections or the replacement, removal, or addition of electrical or mechanical components –Examples include: Replacing a duplex outlet, light switch, fluorescent fixture ballast, fuses, circuit breakers Drilling or punching holes in a live panelboard Pulling conductors into a live panelboard

FN000385/CR, Electrical Safety in the Workplace 14 Fermilab Policy Do Not work on energized electrical equipment unless absolutely necessary. Diagnostic Energized Work is allowed only when the diagnostic activity is not feasible with the circuit de-energized. Manipulative Energized Work is prohibited at Fermilab unless it can be demonstrated that de-energization introduces additional or increased hazards or is infeasible due to equipment design or operational limitations

FN000385/CR, Electrical Safety in the Workplace 15 Fermilab Policy Infeasible does not include Inconvenient Directorate Approval Required for Manipulative Energized Work Fermilab policies and NFPA 70E apply to both the AC Power Distribution system and to Utilization Equipment

FN000385/CR, Electrical Safety in the Workplace 16 Electrical Hazard Analysis Shock Hazard Analysis Arc-Flash Hazard Analysis

FN000385/CR, Electrical Safety in the Workplace 17 Shock Hazard Analysis –Limited Approach Boundary Distance from an exposed live part within which a shock hazard exists Only Qualified persons and escorted unqualified persons are allowed within the Limited Approach Boundary. –Restricted Approach Boundary Distance from an exposed live part within which there is an increased risk of shock due to electrical arc-over that may result from inadvertent movement of personnel working in close proximity to the live part.

FN000385/CR, Electrical Safety in the Workplace 18 Shock Hazard Analysis –Prohibited Approach Boundary Distance from an exposed live part within which work is considered the same as making contact with the live part.

FN000385/CR, Electrical Safety in the Workplace 19 Shock Hazard Analysis

FN000385/CR, Electrical Safety in the Workplace 20 Shock Protection Boundaries

FN000385/CR, Electrical Safety in the Workplace 21 Shock Protection Boundaries

FN000385/CR, Electrical Safety in the Workplace 22 Electrically Insulating Gloves Glove Classes by Use Voltage Procure Through Your Local D/S ES&H Department Gloves must be tested after every 6 months of use through Fermilab’s program (April 1 and October 1 are Scheduled Exchange Dates) Inspect gloves before each use Use Leather Protectors with Electrically Insulating Gloves Class volts Class 0 1,000 volts Class 1 7,500 volts Class 2 17,000 volts Class 3 26,500 volts Class 4 36,000 volts

FN000385/CR, Electrical Safety in the Workplace 23 Arc Flash Hazard Analysis Determines if thermal hazard exists –Identifies required protective equipment Flash Protection Boundary –Distance from an exposed live part within which a person could receive a 2nd degree burn from an arc-flash –For systems 600 volts or less, the default boundary is 4 feet

FN000385/CR, Electrical Safety in the Workplace 24 Arc Flash Hazard Analysis –For voltages above 600 volts, the Flash Protection boundary can be calculated with the general equations –Distance circuit component = [2.65 x MVA bf x t] 1/2 –Distance transformer = [53 x MVA x t] 1/2 MVA bf = bolted fault capacity available at point involved in mega volt-amps MVA = capacity rating of transformer in mega volt-amps

FN000385/CR, Electrical Safety in the Workplace 25 Arc Flash Hazard Analysis Incident Energy Exposure Calculation –Requires Single Line Electrical Drawing (SLED) available fault current conductor wire sizes conductor distances operating voltage of the system trip time for fuses or circuit breakers arc fault is in open air or in a box

FN000385/CR, Electrical Safety in the Workplace 26 Table (C)(9)(a)

FN000385/CR, Electrical Safety in the Workplace 27 Table (C)(9)(a) Footnotes 1 and 3 –Footnote #1 25 kA short circuit current available, 0.03 second (2 cycle) fault clearing time. –Footnote #3 For < 10 kA short circuit current available, the hazard/risk category required may be reduced by one number.

FN000385/CR, Electrical Safety in the Workplace 28 Table (C)(9)(a)

FN000385/CR, Electrical Safety in the Workplace 29 Hazard Risk Clasification

FN000385/CR, Electrical Safety in the Workplace 30 Hazard Risk Clasification

FN000385/CR, Electrical Safety in the Workplace 31 Arc-Flash Protective Clothing Hazard Category defines required PPE NFPA 70E Table 130.7(C)(10) Fermilab Summary for NFPA 70E Arc-Flash Hazard/Risk Categories

FN000385/CR, Electrical Safety in the Workplace 32 Arc-Flash Protective Clothing

FN000385/CR, Electrical Safety in the Workplace 33 Arc-Flash Protective Clothing

FN000385/CR, Electrical Safety in the Workplace 34 Arc-Flash PPE All Hazard Risk Categories Require Eye Protection Hazard Risk Categories 1 and up require –Hard Hats, Leather Gloves, Leather Shoes, and Fire Resistant rated protective clothing Hazard Risk Categories 2 and up require –Arc-rated face shield or flash suit hood and Hearing Protection

FN000385/CR, Electrical Safety in the Workplace 35 Fire Resistant (FR) Clothing Hazard/Risk Category 1 or above, fire resistant or FR clothing is required Arc Thermal Protection Value (ATPV) –Identifies maximum thermal protection the clothing can provide. –PPE such as face shields, hoods, jackets, coats, and coveralls have an ATPV rating Select clothing and equipment that meets or exceeds minimum ATPV required for the Hazard/Risk Category

FN000385/CR, Electrical Safety in the Workplace 36 Fire Resistant (FR) Clothing Wear and care of PPE –Wear cotton or natural fiber non melting clothing –Wear PPE that satisfies the minimum ATPV required –Layering clothing increases protection –Wear clothing loose rather than tight Do not use bleach or fabric softeners on ATPV rated PPE

FN000385/CR, Electrical Safety in the Workplace 37 Electrical Safe Work Condition Determine all possible power sources Electrical Hazard Analysis –Shock Hazard Analysis Limited, Restricted, and Prohibited Approach Boundaries Shock protection PPE –Arc-Flash Hazard Analysis Hazard Risk Category Arc-Flash PPE Flash Protection Boundary

FN000385/CR, Electrical Safety in the Workplace 38 Electrical Safe Work Condition Plan for Emergencies –Know how to de-energize quickly –Be prepared to pull employee free with an insulated rescue hook –Means available to call 3131 –Know CPR and where AED’s are located Protect unqualified persons from work area Don the appropriate PPE

FN000385/CR, Electrical Safety in the Workplace 39 Electrical Safe Work Condition Open disconnect device Perform LOTO –Verification is the most important step F4 Service Building 13.8 KV Disconnect switch failure occurred on Wed Oct 1, 2008

FN000385/CR, Electrical Safety in the Workplace 40 Electrical Safe Work Condition –Voltage Testing (LOTO) Use a meter rated for the task –Test meter both before and after use when performing LOTO –Common observation – People don’t check their meter after performing LOTO –Proximity sensors are not to be used for LOTO –Ground stored energy devices and potential induced voltage sources

FN000385/CR, Electrical Safety in the Workplace 41 Questions Resources –Fermilab Electrical Safety Subcommittee –Division/Section Senior Safety Officer –Division/Section Electrical Coordinator –Line Management Fermilab Summary Guidance Sheets – Enroll in the challenge exam –