* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download PV Systems and Safety
Electric machine wikipedia , lookup
Switched-mode power supply wikipedia , lookup
Mechanical-electrical analogies wikipedia , lookup
History of electromagnetic theory wikipedia , lookup
Electric power system wikipedia , lookup
Public address system wikipedia , lookup
Ground loop (electricity) wikipedia , lookup
Wireless power transfer wikipedia , lookup
Voltage optimisation wikipedia , lookup
Electrification wikipedia , lookup
Amtrak's 25 Hz traction power system wikipedia , lookup
Electrical substation wikipedia , lookup
Electromagnetic compatibility wikipedia , lookup
Electronic engineering wikipedia , lookup
History of electric power transmission wikipedia , lookup
Stray voltage wikipedia , lookup
Surge protector wikipedia , lookup
Telecommunications engineering wikipedia , lookup
Electrical engineering wikipedia , lookup
Alternating current wikipedia , lookup
Power engineering wikipedia , lookup
Portable appliance testing wikipedia , lookup
Electrician wikipedia , lookup
Mains electricity wikipedia , lookup
Ground (electricity) wikipedia , lookup
Electrical wiring wikipedia , lookup
Earthing system wikipedia , lookup
Photovoltaic (PV) Systems and Safety Workshop on Installing Photovoltaic Systems Florida Solar Energy Center Cocoa, Florida 1 Key Elements of a PV System energy source load utilization power conditioning PV Array Inverter Charge Controller load center energy distribution energy conversion energy storage battery electric utility network 2 General Program Standards for PV Installation Practitioners Given a grid-connected PV system design, including major components, drawings and instructions, the PV practitioner will install a grid-connected PV system that meets the needs of the customer, the site, and local code requirements by: 1. Working safely with photovoltaic systems 2. Conducting a site assessment 3. Selecting a system design 4. Adapting the mechanical design to the site 5. Adapting the electrical design to the site 6. Installing subsystems and components at the site 7. Performing a system checkout and inspection 8. Maintaining and troubleshooting the system 3 PV Systems and Safety PV installer safety: Safe work area Safe use of tools and equipment Safe practices for personnel protection Awareness of safety hazards and how to avoid them A safe PV system: PV system codes and standards Public safety codes and standards Identification of safety hazards Identification of environmental hazards 4 The Need for Safe Work Practices and Standards Each year... Nearly 6,000 workplace fatalities 50,000 deaths from workplace-related illnesses 5.7 million non-fatal workplace injuries Injuries alone cost U.S. businesses over $125 billion. Source: OSHA Publication 2056 5 OSHA Safety Categories Personal Protection Equipment (PPE) Electrical Falls Stairways and Ladders Scaffolding Power Tools Materials Handling Excavation Cranes 6 NEC Article 690: Solar Photovoltaic Systems I. General II. Circuit Requirements III. Disconnecting Means IV. Wiring Methods V. Grounding VI. Marking VII. Connection to Other Sources VIII.Storage Batteries IX. Systems Over 600 Volts 7 PV Systems and the National Electrical Code® In addition to Art. 690, other NEC articles may also apply to PV installations: Article 110: Article 210: Article 230: Article 240: Article 250: Article 300: Article 310: Article 400: Article 480: Article 490: Article 685: Article 705: Article 720: Requirements for Electrical Installations Branch Circuits Disconnect Means Overcurrent Protection Grounding Wiring Methods Conductors for General Wiring Flexible Cords and Cables Storage Batteries Equipment, over 600 Volts, Nominal Integrated Electrical Systems Interconnected Electric Power Production Sources Circuits and Equipment Operating at Less than 50 Volts 8 NEC Article 690: Summary Section Contents NEC Cross References I General: Scope, Definitions, Installation, Ground-fault protection, AC modules Article 240 II Circuit Requirements: Maximum voltage, Circuit sizing and current, Overcurrent protection, Stand-alone systems III Disconnecting Means: Conductors, Additional provisions, PV equipment, Fuses, Switches and circuit breakers, Installation and service IV Wiring Methods: Methods permitted, Component interconnections, Connectors, Access to boxes V Grounding: System grounding, Point of system grounding connection, Equipment grounding, Size of equipment grounding conductor, Grounding electrode system VI Marking: Modules, AC modules, PV power source, Point of common connection VII Connection to Other Sources: Identified interactive equipment, Loss of interactive system power, Ampacity of neutral conductor, Unbalanced interconnections, Point of connection Article 230 VIII Storage Batteries: Installation, Charge control, Battery interconnections Articles 400, 480 IX Systems over 600 Volts: General, Definitions Articles 110, 210, 240 Article 230 Articles 310, 400 Article 250 Article 490 9 Personal Protective Equipment (PPE) 10 Personal Protection Equipment Responsibilities Employer Assess workplace for hazards. Provide personal protective equipment (PPE). Determine when to use. Provide PPE training for employees and instruction in proper use. Employee Use PPE in accordance with training received and other instructions. Inspect daily and maintain in a clean and reliable condition. 11 Examples of PPE Body Part Protection Equipment Eye Safety Glasses, Goggles Face Face Shields Head Hard Hats Feet Safety Shoes Hands and arms Gloves Bodies Vests Hearing Earplugs, Earmuffs 12 Eye Protection 13 Eye Protection for Employees Who Wear Eyeglasses Ordinary glasses do not provide the required protection. Proper choices include: Prescription glasses with side shields and protective lenses Goggles that fit comfortably over corrective glasses without disturbing the glasses Goggles that incorporate corrective lenses mounted behind protective lenses 14 Preventing Electrical Hazards: PPE Proper foot protection (not tennis shoes) Rubber insulating gloves, hoods, sleeves, matting, and blankets Hard hat (insulated nonconductive) 15 Safety Shoes Impact-resistant toes and heatresistant soles protect against hot surfaces common in roofing and paving Some have metal insoles to protect against puncture wounds May be electrically conductive for use in explosive atmospheres, or nonconductive to protect from workplace electrical hazards 16 Selecting the Right Hard Hat Class A General service (building construction, shipbuilding, lumbering) Good impact protection but limited voltage protection Class B Electrical/utility work Protects against falling objects and high-voltage shock and burns Class C Designed for comfort, offers limited protection Protects against bumps from fixed objects, but does not protect against falling objects or electrical shock 17 Hand Protection 18 Electrical Safety 19 Facts about Electrical Hazards About 5 workers are electrocuted every week. Causes 12% of young worker workplace deaths. Takes very little electricity to cause harm. Significant risk of causing fires. 20 Electrical Injuries There are four main types of electrical injuries: Electrocution or death due to electrical shock Electrical shock Burns Falls (caused by shock) 21 Shock Severity Severity of the shock depends on: Path of current through the body Amount of current flowing through the body (amps) Duration of the shocking current through the body LOW VOLTAGE DOES NOT MEAN LOW HAZARD 22 Dangers of Electrical Shock Currents above 10 mA* can paralyze or “freeze” muscles. Currents more than 75 mA can cause a rapid, ineffective heartbeat -- death will occur in a few minutes unless a defibrillator is used. 75 mA is not much current – a small power drill uses 30 times as much. Defibrillator in use * mA = milliampere = 1/1,000 of an ampere 23 Burns Most common shockrelated injury Occurs when you touch electrical wiring or equipment that is improperly used or maintained Typically occurs on hands Very serious injury that needs immediate attention 24 Falls from Electrical Shock Electric shock can also cause indirect injuries. Workers in elevated locations who experience a shock may fall, resulting in serious injury or death. 25 Falls in Construction Falls are the leading cause of deaths in the construction industry. Most fatalities occur when employees fall from open-sided floors and through floor openings. Falls from as little as 4 to 6 feet can cause serious lost-time accidents and sometimes death. Open-sided floors and platforms 6 feet or more in height must be guarded. 26 Fall Protection Options Personal Fall Arrest System (PFAS) Guardrails Safety Net 27 Personal Fall Arrest Systems You must be trained how to properly use PFAS. PFAS = anchorage, lifeline and body harness. 28 Safety Line Anchorages Must be independent of any platform anchorage and capable of supporting at least 5,000 pounds per worker. 29 Safety Nets Place as close as possible, but no more than 30 feet below where employees work. 30 Roofs If you work on roofs and can fall more than 6 feet, you must be protected. 31 Ladder Angle Non-self-supporting ladders (that lean against a wall or other support): Position at an angle where the horizontal distance from the top support to the foot of the ladder is 1/4 the working length of the ladder. 32 Ladder Rail Extension When using a portable ladder for access to an upper landing surface, the side rails must extend at least 3 feet above the upper landing surface. 33 Near Energized Electrical Equipment If using ladders where the employee or the ladder could contact exposed energized electrical equipment, they must have nonconductive siderails such as wood or fiberglass. This is an unsafe condition 34 Overhead Power Lines Stay at least 10 feet away. Post warning signs. Assume that lines are energized. Use wood or fiberglass ladders, not metal. Power line workers need special training and PPE. 35 Fall Protection Training Workers should be trained in the following areas (as applicable): The nature of fall hazards in the work area. The correct procedures for erecting, maintaining, and disassembling the fall protection systems to be used. The proper use, placement, care and handling of ladders. The maximum intended load-carrying capacities of ladders. 36 Power Tools Must be fitted with guards and safety switches Extremely hazardous when used improperly Different types determined by their use: Electric Pneumatic Liquid fuel Hydraulic Powder-actuated 37 Switches Hand-held power tools must be equipped with one of the following: Constant pressure switch Shuts off power upon release Examples: circular saw, chain saw, grinder, hand-held power drill On-Off Switch Examples: routers, planers, laminate trimmers, shears, jig saws, nibblers, scroll saws 38 Power Tool Precautions Disconnect tools when not in use, before servicing and cleaning, and when changing accessories. Keep people not involved with the work away from the work. Secure work with clamps or a vise, freeing both hands to operate the tool. Don’t hold the switch button while carrying a plugged-in tool. Keep tools sharp and clean. Consider what you wear – loose clothing and jewelry can get caught in moving parts. Remove damaged electric tools & tag them: “Do Not Use.” 39 Power Tool Precautions Don’t carry portable tools by the cord. Don’t use electric cords to hoist or lower tools. Don’t yank cord or hose to disconnect it. Keep cords and hoses away from heat, oil, and sharp edges. 40 Electric Power Tools To protect a worker from shock, these tools must: have a 3-wire cord plugged into a grounded receptacle be double insulated, or be powered by a low-voltage isolation transformer Double insulated markings Plug with a grounding pin 41 Hazard: Inadequate Wiring Hazard: Wire too small for the current. Example: Portable tool with an extension cord that has a wire too small for the tool The tool will draw more current than the cord can handle, causing overheating and a possible fire without tripping the circuit breaker. The circuit breaker could be the right size for the circuit but not for the smaller-wire extension cord. Wire Gauge WIRE Wire gauge measures wires ranging in size from number 36 to 0 American wire gauge (AWG) 42 Grounding Grounding creates a lowresistance path from a tool to the earth to disperse unwanted current. When a short or lightning occurs, energy flows to the ground, protecting you from electrical shock, injury and death. 43 Hazard: Improper Grounding Tools plugged into improperly grounded circuits may become energized. Broken wire or plug on extension cord Some of the most frequently violated OSHA standards 44 Electric Tools: Good Practices Operate within design limits. Use gloves and safety shoes. Store in a dry place. Don’t use in wet locations unless so approved. Keep work areas well lit. Ensure cords don’t present a tripping hazard. 45 Power Tool Summary Hazards are usually the result of improper tool use or not following one or more of the proper protection techniques: Inspecting the tool before use Using PPE (Personal Protective Equipment) Using guards Properly storing the tool Using safe handling techniques 46 Lockout and Tagging of Circuits Apply locks to power source after de-energizing. Tag deactivated controls. Tag de-energized equipment and circuits at all points where they can be energized. Tags must identify equipment or circuits being worked on. 47 Electrical Equipment Training Train employees working with electric equipment in safe work practices, including: De-energizing electric equipment before inspecting or repairing Using cords, cables, and electric tools that are in good repair Lockout / tagout recognition and procedures Using appropriate protective equipment 48 Summary: Electrical Hazards and Protection Measures Hazards Inadequate wiring Exposed electrical parts Wires with bad insulation Ungrounded electrical systems and tools Overloaded circuits Damaged power tools and equipment Using the wrong PPE and tools Overhead powerlines All hazards are made worse in wet conditions Protective Measures Proper grounding Use GFCIs Use fuses and circuit breakers Guard live parts Lockout/tagout Proper use of flexible cords Close electric panels Training 49 Installer Safety: Electrical Summary Electrical equipment must be: Listed and labeled Free from hazards Used in the proper manner If you use electrical tools you must be: Protected from electrical shock Provided with necessary safety equipment 50 Conclusions PV safety involves the safety of the workers while installing the system and the safety of all others who may come in contact with the system after it is installed. OSHA regulations help keep workers safe. NEC requirements help ensure a safe system. PV installers should be trained in both OSHA regulations and the NEC. Special attention should be paid to fall protection. 51 52