2 Importance of Arc Flash Analysis (“Arc Flash Loss Prevention”) Provides minimum requirements to prevent hazardous electrical exposures to personnel and ensure compliance with regulatory requirements applicable to electrical systems
3 Regulatory Requirements (elements necessary for Worker Safety) OSHA = Shall Provide Worker SafetyNFPA 70E = How to provide Worker SafetyEmployer Responsibility = ExecutionFocus on safety, promote training, use best practices
4 Electrical Hazards Consist of: Electric ShockArc FlashArc BlastOther Hazards
5 Electric ShockAn electric shock occurs when electric current passes through the body. This can happen when touching an energized part. If the electric current passes through the chest or head, death can result.
6 Effects of Electrical Current in the Human Body Below 1 milliampere: - Generally not perceptible1 milliampere: - Faint tingle5 milliamperes: - Slight shock felt; not painful but disturbing. Average individual can let go. Strong involuntary reactions can lead to other injuries.6–25 milliamperes (women): - Painful shock, loss of muscular control*9–30 milliamperes (men): - The freezing current or " let-go" range.* Individual cannot let go, but can be thrown away from the circuit if extensor muscles are stimulated.50–150 milliamperes: - Extreme pain, respiratory arrest, severe muscular contractions. Death is possible.1,000–4,300 milliamperes: - Rhythmic pumping action of the heart ceases. Muscular contraction and nerve damage occur; death likely.10,000 milliamperes: - Cardiac arrest, severe burns; death probable* If the extensor muscles are excited by the shock, the person may be thrown away from the power source. Source: W.B. Kouwenhoven, " Human Safety and Electric Shock," Electrical Safety Practices, Monograph, 112, Instrument Society of America, p. 93. November 1968.
7 Arc Flash/BlastAn arc flash (also known as arc blast) is a sudden, explosive electrical arc that results from a short circuit through air. The air in the vicinity of an arc flash is heated to between 5,000 and 35,000 degrees in no more than 1/1000 of a second, becoming an electrically-conductive plasma. The sudden heating can cause a shock wave blast equivalent to several sticks of dynamite and carrying vaporized metal and shrapnel
8 Safe Work Practices OSHA 1910.333 NFPA 70E 110.8 Potential for shock or other injuryWorking on or near live exposed partsPractices must be consistent with the extent of the hazardNFPA 70E 110.8Requires deenergizingRequires worker to be qualifiedRequires hazard analysisElectrical work permit
9 NFPA 70E Requirements for Working on or Near Live Parts Perform Arc Flash AnalysisSelect Personal Protective Equipment (PPE)Complete Energized Electrical Work PermitComplete Task Specific TrainingComplete a job briefing session
10 Arc Flash Analysis Establish Shock Protection Boundary (approach boundaries) – used to reduce shock hazardConduct Flash Hazard AnalysisEstablish Flash Protection BoundaryUsed to reduce arc flash hazards and may reduce arc blast hazardsSelect Personal Protective EquipmentAnalysis per NFPA 70E requires update every 5yrs
11 Approach Boundary to Live Parts Limited (42 in)Restricted (12 in)Prohibited (1 in)Based on system voltage = 480VNFPA 70E, Annex C, Figure C.1.2.4
12 Flash Protection Boundaries (FPB) Using NFPA 70E, the methods to determine FPBDefaults (i.e. tables)Perform Analysis that uses Calculation Methods
15 PPE Designed to protect specific areas of the body Eye Protection Neck, Face, Head, ChinArm & Hand ProtectionBody ProtectionLeg & Foot Protection
16 PPE - GlovesVoltage rated gloves are REQUIRED for all voltage testing above 50 volts
17 OSHA/NFPA 70E General Industry Requirements OSHA (a)Employees exposed to potential electrical hazards shall use protective equipment that is appropriate for the specific areas of the body to be protected and for the work to be performedNFPA 70E 130.7Provides standards for equipmentHazard Risk TablePPE MatrixExtensive detail for worker protectionProtective Equipment
18 OSHA FinesFor non-compliance, OSHA may audit a facility and issue finesMost recently: U.S. Postal Service$420,000 (pending) – single facility
19 A Facility’s Electrical System A facility’s electrical system operates as a single, dynamic system. Its performance is dependent on the properties of each component and the loads connected to it.Many facilities expand project by project using different design and construction teams. Even though each specific project may be well planned and designed, it’s often the case that the area of work specific to the project is limited to only a portion of the existing electrical distribution system.In addition, due to the need for maintenance and emergency repairs, system components are often replaced with devices that are different than originally installed due to availability and cost.Because of these occurrences, it’s common that no one has an overall and complete understanding of the entire electrical system.
20 ToolsMost firms that provide arc flash services utilize specially designed software for electrical system modeling in short circuit and arc flash studies.Such as SKM Power System Tools
21 Process/Approach to Complete a Study As-built DocumentationThe usual starting point is to gather all existing drawings an Owner has and sort it by location and date. (One-Line Documentation)VerificationSurvey each site and verify one-line documentation. Acquire missing info.PD types/sizes/settings, cable lengths, Xfmr impedance valuesLoadingLoad the information into SKM and run Short Circuit, Coordination, Arc Flash
22 Ex: How to Initiate a Study “Large School System” Herndon HSPyramidLangley HS PyramidMcLean HS PyramidAldrin ESChurchill Road ESChesterbrook ESArmstrong ESColvin Run ESFranklin Sherman ESClearview ESForestville ESHaycock ESDranesville ESGreat Falls ESKent Gardens ESHerndon ESSpring Hill ESTimber Lane ESHutchison ESCooper MSLongfellow MSHerndon MSLangley HSMcLean HS
24 Cluster Analysis Approach (5) field survey teams composed of (2) people each assigned to various sites within a cluster. All survey is schedule/time dependent.CLUSTER SITES PYRAMIDS TEAM EST. TIME (mo.)C AC BC CC DC EFollowing C1-C5C A/E 5 - 7C CC B/D 6 -8
25 1ST Step - Collect Hard Copy Data Existing Building Documents -Electrical One-Line Diagrams -Floor Plans -Maintenance Documents
28 Gathering of Information During Survey Process Protective Device InformationLocation, (Room/Panel/What’s it feeding?)Make, Model, ManufactureAIC and Trip Plug RatingSettings
29 3rd Step - Load the Data Build SKM One-Line Diagrams for each site Verify accuracy of informationAcquire Utility Company contribution informationRun/Review Short Circuit CalculationsThe maximum fault current can be calculated at each electrical buss in the system by knowing the properties of the power sources that will provide the current, and using the impedance values of the circuits that connect the bussesUnderstanding the “Duty Rating” of the equipment by comparing the available fault current to the rating of the “protective device”
31 Run a Short Circuit Study Compare Protective Device Ratings Breakers/fuses Against the available 3-phase and SLG Fault currents.
32 Selective Coordination In order to be assured that all over current protection devices are coordinated, it is necessary to look at the time vs. current characteristic of each device and compare it to the characteristics of any upstream devices.
34 Poor CoordinationMain Breaker Trips, Shutting Down the Entire Switchboard
35 Adjustments to be Made Settings LTPU - Long time pick up LTD – Long time delaySTPU – Short time PickupSTD – Short time DelayI²t – Short time delay bendINST – InstantaneousGFPU – Ground Fault Pick upGFD – Ground Fault DelayGFI²t – Ground Fault Delay bend
37 4th Step - Arc Flash Evaluation To calculate the available arc flash energy, it is necessary to perform a short circuit study to determine the magnitude of the current that will flow in a fault condition, and also a coordination study to determine the length of time it takes for an Over Current Protection Devices (OCPD) to clear the fault.
40 5th Step – Review Results/Recommendations Reports are generated based Existing (as is) conditions. Identifies the problem areas with bad coordination and high incident energy categoriesReports are generated based on Recommendations (best scenario) to better coordinate devices and lower arc flash incident energy categoriesBegin Training Process
41 ON-SITE ELECTRICAL SAFETY TRAINING A balance of safety & technical training is essential for continuous improvementDesigned to protect lives, prevent disabling injuries, and prevent damage to your facility & equipment.Personnel learn about personal safety for working on or around electrical systemsUnderstand the proper use of materials and procedures for doing electrical workHands-on practical instruction that they can immediately apply when they go back to their workplaceWho should be trained? Anyone who works on or around any electrically energized equipment
43 Definition Qualified Person OSHAOne who has received training in and has demonstrated skills and knowledge in the construction and operation of electric equipment and installations and the hazards involved.NFPA 70ESkills and knowledge related to the construction and operation of the equipment and has received safety training on the hazards involved.
44 Qualified PersonAre they qualified to be working on live exposed electrical parts?
45 Perception of a Qualified Person Licensed Electrician = qualified employeeTraining CertificatesYears of Experience“I have never been hurt”
46 Summary Don’t assume that a person is qualified When in doubt, ask!!!! Their qualifications can affect you, your co-workers, and your company, the facility, etc…Best Practice: Whenever possible, work on electrical equipment de-energizedRemember, regulations are minimum requirementsUtilize best resources availableDevelop a principle directive (Golden Rule!)
47 Multi-Disciplined Team Partial Client List Quick FactsEstablished in 198175 employees4 office locationsMassachusettsNorth CarolinaVermontVirginiaMulti-Disciplined Team25 Mechanical25 Electrical & Controls15 Instrument Technicians10 CAD/AdminPartial Client ListHealth CareBurlington Community Health Ctr.Fanny Allen HospitalFletcher Allen Health CareLittleton HospitalUniversity Health CareUniversity of Vermont, Given MedicalUpper Connecticut Valley HospitalVA HospitalBioTech & PharmaceuticalAstra ZenecaBaxter BioscienceCovidienGenzymeJohnson & JohnsonLifeNetLonza BiologicsMylan TechnologiesNovartisPfizer Global R&DSiemens Medical SolutionsStryker BiotechWyethGeographicallyPercent of fee revenueMA RegionVT Region40%20%Mid-Atlantic RegionServicesPercent of fee revenueCommissioningEngineeringSystems Integration30%35%MarketsPercent of fee revenueLife Sciences, Health Care, R&D, Higher EducationMicroelectronicsIndustrial70%15%Electrical systems design is at the core of our well established MEP firm. Leveraging our knowledge and expertise we can conduct arc flash analysis with precision, and provide recommendations based on our vast experience.A comprehensive study of the electrical system can provide the Owner the necessary tools to predict possible system failures, as well as the data necessary for safety, maintenance, and future planning.