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Electrical wiring systems and safety devices.pptx

Electricity can cause serious injuries or death if safety precautions are not followed. Some common electrical hazards include exposed electrical parts, overloaded circuits, defective insulation, improper grounding, and damaged power tools. It is important for workers to be aware of electrical hazards and follow safety practices such as inspecting cords before use, avoiding overloading circuits, staying away from unguarded conductors, and wearing appropriate personal protective equipment when working with electricity. Training workers on electrical safety practices, lockout/tagout procedures, and safe work practices is essential for prevention of electrical accidents.

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Electricity is an important part of our modern world and sometimes it is easy to forget just how dangerous it can be. Given the correct circumstances, electricity can cause serious injuries or even death. Electrical Safety
• Electrocution is the cause of 12% of all workplace deaths among young workers. • Electrocution is the third leading cause of work-related deaths among 16 and 17-year- olds. Electrical Safety
The most common types of electrical injuries are: • Electrical shock • Electrocution (death due to electrical shock) • Burns • Falls Electrical Injuries
Electrical Hazards To avoid injuries, you should be aware of electrical hazards. Some of the most common electrical hazards are: • Exposed electrical parts • Overloaded circuits • Defective insulation • Improper grounding • Damaged power tools • Overhead power lines • Wet conditions Let’s take a closer look at each of these hazards.
Exposed electrical parts can include: • Breaker boxes without a cover • Electrical terminals in motors, appliances, and electronic equipment Exposed Electrical Parts
Aground fault circuit interrupter (GFCI) detects current leaking from a circuit to ground and shuts the current off. • Circuit breakers • Fuses • Ground fault circuit interrupters Overloaded Circuits Receptacle type
Defective Insulation To protect you, electrical wires are insulated by a plastic or rubber covering. Insulation prevents conductors from coming in contact with each other and with people. Make sure the insulation of tools and cords you are using is not damaged.
Power Tools To protect you from shock, burns and electrocution, tools must: • Have a three-wire cord with ground and be plugged into a grounded receptacle. • Be double insulated. • Be powered by a low-voltage isolation transformer.
Wet Conditions Wet conditions are hazardous because you can become an easy path for electrical current. There are many circumstances that create wet conditions: • Standing in water • Wet clothing • High humidity • Perspiration
Safe Work Practices You can StartSafe and StaySafe by using the following safe work practices: • Inspect cords before each use • Never overload a circuit • Stay away from all unguarded conductors • To unplug, pull on the plug, not the cord • Don’t wear jewelry or use other metal objects around electrical equipment
Training concerning electricity is very important. Training for employees working with electrical equipment must include how to: • De-energize the equipment • Use lockout and tag procedures • Use insulating protective equipment • Maintain a safe distance from energized parts • Use appropriate PPE Safe Work Practices: Training
Electrical Safety for the Non-Electrical Skilled Worker Recognizing and Mitigating Specific Hazards in the Work Place Encountered by the Non- Electrical Skilled Worker Module 6
Non-Electrical Skilled Worker  This training provides additional electrical safety training for electrical hazards non- electrical skilled workers are exposed to in the work place.  It is developed as an add-on module to the basic electrical safety training module for non-electrical workers.
Review of Basic Electrical Safety Hazard Awareness for the Non-Electrical Worker  You should have taken as a prerequisite for this training “Basic Electrical Safety Hazard Awareness for Non-Electrical Personnel”.  This training covered the hazards associated with electrical energy – Shock, Arc and Blast. These hazards can cause disability or death. You were taught how to recognize electrical hazards.
Review of Basic Electrical Safety Hazard Awareness for the Non-Electrical Worker (continued)  You were taught basic electrical safety that included:  Ground-fault Circuit Interrupters (GFCIs)  Basic electrical cord safety  Resetting Breakers  Conductive Apparel  Wall Penetrations  Safe Work Practices for Equipment Applications  Only qualified electrical workers can perform electrical work
Review of Basic Electrical Safety Hazard Awareness for the Non-Electrical Worker (cont.)  You were taught basic electrical safety that included:  What to do in case of an electrical emergency.  To inspect your work area for unsafe electrical conditions.  To use equipment per its Listing and Labeling instructions i.e. no daisy chaining, no overloading of circuits, etc.  What to do if you identify an electrical hazard.  To contact your Site Electrical Safety Officer or Safety Engineer for specific electrical safety items.
Who is considered a Non-Electrical Skilled Worker? The following list of workers includes but is not limited to those who would be considered a “Non-Electrical Skilled Worker”. Fitters, Painters, Carpenters, Laborers, Utility Operators, Equipment Operators, D&D Workers, Janitors, Radiation Control Technicians, Waste Handlers and Warehouse Workers.
Non-Electrical Skilled Workers (cont.) Non-Electrical Skilled workers are:  Exposed to specific electrical hazards  Expected to work safely around electrical energy  To use electrical tools safely  To follow electrical safety requirements  To help keep other workers safe from electrical hazards.  Obey all postings and barriers protecting exposed energized electrical hazards.
The following slides will discuss specific electrical hazards the non-electrical skilled worker is exposed to in the work place and the methods used to mitigate the hazards. Hazards of Electricity Shock Arc Blast
Safe Work Practices: Lockout/Tagout When performing lockout/tagout on circuits, trained employees will do the following: • Turn off the power supply • Put a lock on all power sources to the circuit • Apply a tag • Test the circuit
The most effective way to protect against electrical hazards is to use LO/TO.  Your facility will have specific requirements for LO/TO. Always comply with the requirements.  Only LO/TO qualified employees may work under the protection of a LO/TO.  LO/TO accomplishes a zero energy state and there is no electrical hazard.  You are required to comply with all LO/TO requirements.  Failure to comply can result in injury or death! DO NOT OPERATE!
Lockout/Tagout  Your personal lock and personal danger tag is what protects you from systems being re-energized while you are working on them.  You are the only person authorized to remove them except under specially controlled conditions.  If you don’t install them, you are not protected!
AGround Fault Circuit Interrupter (GFCI) is a very effective device to protect employees in the work place from electrical shock.  The number of deaths from electrical shock in the work place has been cut in half since GFCIs have been introduced.  GFCIs are required for all maintenance activities.  GFCIs protect you from electrical shock by tripping on current leakage to ground, which may be through you.  Plugging one GFCI into another one does not create a hazard. The most sensitive one will trip first.  GFCIs may be permanently installed in the facility or a portable device. – Use them.
Use of Specific Safety-Related Equipment and Work Practices GFCIs  Ground Fault Circuit Interrupters (GFCIs) are required for all 125-volt, single phase, 15 and 20-ampere receptacle outlets used for temporary electric power, or as an extension to the power supply cord.  Test Before Use. Push the test button and verify the GFCI has shut off by plugging a safe device into it (i.e. portable lamp or tool). If it doesn’t shut off, don’t use it. Reset it. If it turns on, it is safe to use.  Report a malfunctioning GFCI to the designated facility organization.
GFCIs  Most facilities will allow resetting the GFCI one time. Verify with your facility.  If it trips a second time, have it evaluated by a qualified electrical worker.  It may have tripped to save your life!  Repeated resetting is not allowed.
Circuit Breaker Tripping Anytime a circuit has been de- energized by the operation of an over current protective device (such as a fuse or circuit breaker) by a short circuit or ground-fault, the circuit must be checked by a qualified person to determine if it can be reenergized safely. The repetitive manual re-closing of circuit breakers or reenergizing circuits through replacing fuses is prohibited.
 If you are allowed to reset circuit breakers or other electrical switches, position yourself in the safest location possible.  Never stand directly in front of or reach across the device.  Some facilities have specific requirements for who is allowed to operate breakers and disconnects. Make sure you know the requirement before performing these actions. Circuit Breaker Tripping
Moisture provides a conductive path that could result in death. Never work with wet tools or clothing. Remove Your Jewelry.
Use of Specific Safety-Related Equipment and Work Practices Portable Electric Equipment and Flexible Cord Set requirements:  The user must visually inspect the equipment for defects and damage before they are used on any shift.  If the tool or cord set is damaged, take it out of service or have it repaired.
Portable Electric Tools - Things to look for: Damaged/Broken case Ground prong missing on three-prong plugs. Some tools are double insulated and won’t have a ground prong. That’s OK. Damaged Cord – outer sheath broken
Cords – Items to consider before use. 1. Use per Listing and Labeling 2. Inner wires exposed – Don’t use. 3. Plug not fully seated – Don’t use. 4. Cords run through doors / pinch points – Don’t use. 5. Outer sheath damaged – Don’t use. 6. Cord tightly coiled may cause a problem – Don’t use. 7. Tightly coiled cord that had a meltdown because it couldn’t cool properly when overloaded. 8. Cords must be GFCI protected or under anAssured Equipment Ground Conductor program. 1 2 3 4 5 6 7 8
Extension cords should be a minimum of 16AWG and be rated for the equipment in use. The following is a guide that might be helpful in selecting the cord: Extension Cord Ampere Rating Wire Size (Copper) Single Phase Two and Three Conductor Cords Three Phase Cords 16AWG 13 amps 10 amps 14AWG 18 amps 15 amps 12AWG 25 amps 20 amps 10AWG 30 amps 25 amps 8AWG 40 amps 35 amps 6AWG 55 amps 45 amps 4AWG 70 amps 60 amps 2AWG 95 amps 80 amps RECOMMENDED WIRE SIZE MAXIMUM LENGTH AWG #16 — 25 Feet AWG #14 — 50 Feet AWG #12 — 75 Feet AWG #10 — 100 Feet
Extension cords shall:  Be protected from physical damage at all times.  Be inspected before use.  Be routed so trip, pinch, abrasion, snagging, etc. cannot occur.  Not be used as a substitute for permanent wiring.  Be suitable for the environment i.e. outside, wet, sunlight, etc.  Shall have slack – not drawn out tight.  Shall be unplugged by grasping the plug not the cord.
Ladders used around electrical hazards must have non-conductive side rails. Ladders with non-conductive side rails that are contaminated with paint, greases or other coatings may no longer be non-conductive. Check them out. Stay away from exposed energized equipment. Always look up before you lift or climb up.
Be aware of overhead exposed energized equipment such as overhead lines, cords, or overhead crane rails. Minimum approach distance to overhead lines below 72,500 volts is 10 feet. (LimitedApproach Boundary - 70E) • Look Up and Stay Alive! • There may be other requirements that apply to approach distances to overhead lines. Make sure you inquire about these requirements. • Possible examples may include:  The use of a designated spotter.  Approach distances may be different than 70E requirements.  Overhead utilities may be under separate management.
The National Electrical Code (NEC) has specific clearance requirements around electrical equipment to maintain safe working clearances for electrical workers. These are dedicated spaces and include width, height, and depth requirements. The clearance distances are based on configuration and voltage level. You must keep these spaces clear. Check with a qualified electrical worker to ensure you do not store or install materials and equipment in theses dedicated spaces.
Batteries present special hazards in the work place. They may contain an acid or an alkaline substance in the electrolyte. If you get electrolyte on you, rinse with water for 15 minutes then get medical help. Failure to do this may lead to severe burns or blindness. Most batteries give off explosive gasses when charged. Make sure adequate ventilation is available. Don’t cause sparks or flames in the vicinity of batteries. Acatastrophic explosion may occur. Batteries can store significant amounts of electrical energy. Do not use conductive equipment/tools around batteries. If you cause anARC, you can be severely injured. Remember, there is no off switch on a battery!
If you must perform work around batteries or battery racks, eye wash/drench stations are required. Spill kits for the electrolyte are to be available. Use non-sparking/non- conductive tools.
Electrical System Intrusions  One of the most common occurrences with electrical systems around the DOE complex is excavating, cutting or drilling into electrical systems.  There are many methods of trying to identify buried or concealed electrical conduits and cables. None of them are fool proof.  Facilities have developed methods and procedures to help prevent these occurrences.  If you are involved in this type of activity, it is your responsibility to comply with facility requirements.
If location or condition of energized electrical systems is uncertain, utilize electrically rated PPE and other protective measures such as drill stops, hand digging, vacuum excavators, etc. Conduit cut – Location was right, depth was wrong.
AREA IN FRONT OF THIS ELECTRICAL PANEL MUST BE KEPT CLEAR FOR 36 INCHES OSHA - NEC REGULATIONS C A U T I O N HIGH VOLTAGE Signs, Symbols, Tags, and Barricades are used to warn personnel of potential electrical hazards. OBEYALLSIGNSAND BARRIERS!
REMEMBER!  The results of a mistake with electrical energy occur at the speed of light. There is not time to react after the error is made. You must think ahead.  Pre-job briefs, planned work instructions, and facility requirements are not optional. Pay attention and obey all the rules, not just the ones that are convenient. They provide the edge you need to be safe with electrical energy. Post-job reviews help keep us from repeating errors – participate in them. You are responsible for your safety.
Summary It is very important to StartSafe and StaySafe around electricity. In order to do so: • Know the hazards • Plan your work and plan for safety • Avoid wet working conditions and other dangers • Avoid overhead power lines • Use proper wiring and connectors • Use and maintain tools properly • Wear the correct PPE for the job
Summary  Many items concerning electrical safety have been presented. It isn’t possible to cover all the hazards electrical energy can present.  If you identify a hazard, make sure you and others are safe and then report it immediately to the proper authority for your work location.  70E requires electrical workers to be ALERT.  You are also required to be ALERT and AWARE of potential electrical hazards. If you are not, you can be severely injured or killed  Above all, BE SAFE.
Electrical Wiring Systems
Methods of Electrical Wiring Systems • Wiring (a process of connecting various accessories for distribution of electrical energy from supplier’s meter board to home appliances such as lamps, fans and other domestic appliances is known as Electrical Wiring)
Joint Box or Tee or Jointing System • In this method of wiring, connections to appliances are made through joints. These joints are made in joint boxes by means of suitable connectors or joints cutouts. This method of wiring doesn’t consume too much cables size. • You might think because this method of wiring doesn’t require too much cable it is therefore cheaper. It is of course but the money you saved from buying cables will be used in buying joint boxes, thus equation is balanced. This method is suitable for temporary installations and it is cheap
Loop-in or Looping System • This method of wiring is universally used in wiring. Lamps and other appliances are connected in parallel so that each of the appliances can be controlled individually. When a connection is required at a light or switch, the feed conductor is looped in by bringing it directly to the terminal and then carrying it forward again to the next point to be fed. • The switch and light feeds are carried round the circuit in a series of loops from one point to another until the last on the circuit is reached. The phase or line conductors are looped either in switchboard or box and neutrals are looped either in switchboard or from light or fan. Line or phase should never be looped from light or fan.
Advantages of Loop-In Method of Wiring • It doesn’t require joint boxes and so money is saved • In loop – in systems, no joint is concealed beneath floors or in roof spaces. • Fault location is made easy as the points are made only at outlets so that they are
Disadvantages of Loop-In Method of Wiring •Length of wire or cables required is more and voltage drop and copper losses are therefore more •Looping – in switches and
Different Types of Electric al Wiring Systems 1. Cleat Wiring • This system of wiring comprise of ordinary VIR or PVC insulated wires (occasionally, sheathed and weather proof cable) braided and compounded held on walls or ceilings by means of porcelain cleats, Plastic or wood. • Cleat wiring system is a temporary wiring system therefore it is not suitable for domestic premises. The use of cleat wiring system is over nowadays.
Different Types of Electric al Wiring Systems
Different Types of Electric al Wiring Systems