safety of electrical

Recognizing and Mitigating Specific Hazards in the Work Place Encountered by the Non-Electrical Skilled Worker

It is developed as an add-on module to the basic electrical safety training module for non-electrical workers.

This training provides additional electrical safety training for electrical hazards non-electrical skilled workers are exposed to in the work place.

Non-Electrical Skilled Worker

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”.

v    This training covered the hazards associated with electrical energy – Shock, Arc and Blast.

Ø     These hazards can cause disability or death.

Ø     You were taught how to recognize electrical hazards.

 v    You were taught basic electrical safety that included:

Ø     Ground-fault Circuit Interrupters (GFCIs)

Ø     Basic electrical cord safety

Ø     Resetting Breakers

Ø     Conductive Apparel

Ø     Wall Penetrations

Ø     Safe Work Practices for Equipment Applications

Ø     Only qualified electrical workers can perform electrical work

 v     You were taught basic electrical safety that included:

Ø     What to do in case of an electrical emergency.

Ø     To inspect your work area for unsafe electrical conditions.

Ø     To use equipment per its Listing and Labeling instructions i.e. no daisy chaining, no overloading of circuits, etc.

Ø     What to do if you identify an electrical hazard.

Ø     To contact your Site Electrical Safety Officer or Safety Engineer for specific electrical safety items.

 v   The following list of workers includes but is not limited to those who would be considered a “Non-Electrical Skilled Worker”. 

Ø    Fitters, Painters, Carpenters, Laborers, Utility Operators, Equipment Operators, D&D Workers, Janitors, Radiation Control Technicians, Waste Handlers and Warehouse Workers.

 v   Non-Electrical Skilled workers are:

Ø    Exposed to specific electrical hazards

Ø    Expected to work safely around electrical energy

Ø    To use electrical tools safely

Ø    To follow electrical safety requirements

Ø    To help keep other workers safe from electrical hazards.

Ø    Obey all postings and barriers protecting exposed energized electrical hazards.

DOE and NFPA 70E Requirements

v   DOE has identified NFPA 70E (70E) as the basis document for electrical safety at its facilities.

v   Compliance with 70E is mandatory.

v   70E has specific requirements for working safely with electrical energy.

 v   Only Qualified Electrical Workers can perform work “ON” or “NEAR” electrical equipment 

v   Non-electrical workers may use electrical equipment, but must be trained to   know the hazards of the equipment and how to use the equipment safely.   

v   If you don’t know how to operate a piece of equipment safely and don’t know the hazards involved in it use, stop work and get the required training.  

v   70E requirements for energized work apply if an exposed energized condition exists.  

v   70E requires that an electrically safe work condition (Lockout/Tagout – LO/TO) must be established unless work around energized equipment with exposed electrical components is permitted with all the required safety precautions established.

 v   If an exposed energized condition exists, there will be a Flash Protection Boundary and a Shock Protection  Boundary that will have specific PPE and access requirements.

v   These boundaries are established to protect you from the heat energy of an arc and from getting shocked.

v   70E requires proper barriers, posting, and/or attendants to inform unqualified workers of existing hazards.

v   The work control document should address these boundaries and your work task relationship to them.

v   Do not cross these boundaries unless you are qualified and authorized or are escorted by a qualified electrical worker.

v   You must have the PPE required by 70E for the boundary to be crossed. 

electrical welding

Welding Processes

 A Brief History of Welding

  Late 19^th Century

Scientists/engineers apply advances in electricity to heat and/or join metals (Le Chatelier, Joule, etc.)

Early 20^th Century

Prior to WWI welding was not trusted as a method to join two metals due to crack issues

1930’s and 40’s

Industrial welding gains acceptance and is used extensively in the war effort to build tanks, aircraft, ships, etc.

Modern Welding

the nuclear/space age helps bring welding from an art to a science

 

  Weldability of a Metal

  Metallurgical Capacity Parent metal will join with the weld metal without formation of deleterious constituents or alloysMechanical SoundnessJoint will be free from discontinuities, gas porosity, shrinkage, slag, or cracksServiceabilityWeld is able to perform under varying conditions or service (e.g., extreme temperatures, corrosive environments, fatigue, high pressures, etc.)

 Fusion Welding Principles

 # Base metal is melted

 # Filler metal may be added

 # Heat is supplied by various means

 # Oxyacetylene gas

 # Electric Arc

 # Plasma Arc

 # Laser

 Fusion Welding

What is the difference between active elements and passive elements

This artile explans the difference betwwen the active elements and passive elements with examples and relative pictures. "A network is an interconnection of two or more elements.If this interconnection involves at least one closed circuit,the network is also called as an electrical circuit".

The classification of network elements are 2 types

1.Active elements
2.Passive elements

    1.Active Elements : The elements which are capable of delivering energy to devices or networks connected across them are known as active elements .
Basically hee are two kinds of active elements as follows .
(i) Independent voltage source
(ii) Independent current source
(i)An independent vootage sourse is a sourse in which the voltage source us a source in which the voltage across the terminals is independent of current passing through it ,

The above figure shows the cicuit representation and V-I characteristics of an ideal sourse.The voltage source is termed as a D.C voltage sourse if it has a constant voltage and is represented as follows ,

The V-I characteristics of a practical voltage source is shown below .

(ii)An independent current sourse is asourse which can deliver a constant current independentof volatge across its terminals.The circuit representation and the V-I characteristics of an ideal current sourse are as shown below.

Practically,the current sourse doesnot posses an ideal behavior .The V-I characteristics of a practical current sourse is as shown below.

2.Passive Elements The elements which cannot deliver power and can only receive the power are known as passive elements.
Basically,there are three kinds of passive elements

(a) Resistor-which absorbs the energy

(b) Inductor-which stores the energy in magnetic field

(c) Capacitor-which stores the energy in an electric field

What is the Difference Between a Current Transformers and a Voltage Transformers ?

The Difference Between a Current Transformers (CT) and a Voltage Transformers(VT) with circuit diagram, A transformer is a device that steps up, or steps down voltage. During this process current is also stepped up or down:however, voltage and current are inversely proportional ( meaning an increase in voltage results in a decrease in current and vice versa ).

current ( 1 amrere ) at the secondary...and a step down transformer with the As an example: A step up transformer of 10:1 ratio with 12 volts and 10 amper of current applied to the primary will have ten times the voltage ( 120 volts ) and ten times less same turns ratio with 120 volts and 1 ampere applied to the primary will have 12 volts and ten ampere available at the secondary. The electricity supplied into homes and bussiness uses wires carrying very high voltage and low current over long distances, then uses step down transformers to step down the voltage and step up the current. 

However, in power engineering and protective relaying applications, there are what are called "instrument transformers" which have the specific purpose of providing information to devices (such as relays or meters) about the voltages or currents in the power system. Therefore, there are some differences in construction and connectivity between a Current Transformer (CT) and a Voltage (or Potential) Transformer (PT).

 A CT will typically have a toroidal core and evenly distributed secondary windings so as to minimize leakage reactance. The primary is typically the main power line conductor, which passes directly through the toroidal core. This type of transformer is specifically for the purpose of measuring current values, and the secondary windings cannot be left open-circuited, or a large voltage will be produce, resulting in dielectric failure (and often an explosion). If a device is not connected to the CT, its secondary must be short-circuited. 

A PT is connected between the main conductor and ground and can be either wound in the normal way, or the voltage can be taken from a subsection of a string of capacitors (this is called a Capacitive Voltage Tansformer or CVT, and is usually cheaper than the wound type, but is typically not as accurate). This type of transformer measures voltage values, and the secondary winding cannot be short-circuited, as this will produce excessively high currents, resulting in the failure of the PT or the wires it is connected to. A PT can be left open-circuited. 

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Differences Between C.T and P.T 

CURRENT TRANSFORMER	POTENTIAL TRANSFORMER
The secondary of a C.T can not be open circuited on any circumstance when it is under service.	The secondary of  a P.T can be open circuited without any damage being caused either to the operator or the transformer.
A CT may be considered as a series transformer.	P.T may be considered as a parallel transformer.
The primary current in a C.T is independent of the secondary circuit conditions (burden).	The primary current of a P.T depends upon the secondary circuit conditions (burden).
The primary winding of the CT is connected in series with the line carring the current to be measured. Hence it carries of the full line current.	The primary winding P.T is connected across the line of voltage to be measured. Hence the full line voltage is impressed across its terminal.
With the help of CT, a 5A ammeter can be used measure a high current like 200A.	With the help of P.T, a 120V voltmeter can be used to measure very high voltages like 11KV.

Original History of Electricity

By md nahid sheikh

In the history of electricity, no single defining moment exists. The way we produce, distribute, install, and use electricity and the devices it powers is the culmination of nearly 300 years of research and development.

Prominent contributors to today's electrically energized world (listed in alphabetical order) include:

 Andre-Maire Ampere (1775-1836), a French physicist who developed the System International daunts (SI).

 Alexander Graham Bell (1847-1922), inventor of the telephone. A mostly home-taught member of a Scottish family interested in issues of speech and deafness, Bell followed his father, Alexander Melville Bell, as a teacher of the deaf. In the 1870s, funded by the fathers of two of his students, Bell studied how electricity could transmit sound.

 Ferdinand Bram (1850-1918), a German physicist who shared a Nobel Prize with Guillermo Marconi for contributions to the development of radiotelegraphy.

 Henry Cavendish (1731-1810), a reclusive, unpublished English scientist whose work was replicated several decades later by Ohm.

 Thomas Doolittle, a Connecticut mill worker who, in 1876, devised a way to make the first hard-drawn copper wire strong enough for use by the telegraphy industry, in place of iron wire. The young commercial electric and telephone industry quickly took advantage of the new wire.

 Thomas A. Edison (1847-1931), the most productive electrical explorer. He invented the electric light bulb and many other products that electricians use or install.

Benjamin Franklin (1706-1790), an American diplomat and natural philosopher, he proved that lightning and electricity were the same.

 Luigi Galvani (1737-1798), an Italian physician and physicist, his early discoveries led to the invention of the voltaic pile.

 Guillermo Marconi (1874-1937), an Italian physicist who won the Nobel Prize for his invention of a system of radiotelegraphy.

 Georg Simon Ohm (1789-1854), a German physicist and the discoverer of Ohm's Law, which states that resistance, equals the ratio of the potential difference to current.

 Nicola Tesla (1856-1943), a Serbian-American inventor who discovered rotating magnetic fields. George Westinghouse purchased Tesla's patent rights.

 Alessandro Giuseppe Antonio Anastasia Volta (1745-1827), an Italian physicist who invented the electric battery. The electrical unit "volt" is named for Volta.

 George Westinghouse (1846-1914), an able adapter of other people's research, purchased their patents and expanded on their work. His first patent was received for a train air brake. In 1869, he formed the Westinghouse Air Brake Company. Eventually, he held 360 patents and founded six companies. He lost control of his companies in the 1907 panic, but went on working for them for another three years.

The experiences of electricity's founding fathers parallel in many ways the electronic technology breakthroughs of the past half-century that have brought us a whirlwind of innovation in computer hardware, software, and Internet communications. Just as a wave of electrical inventions dramatically changed the world as the 20th century progressed, so can we anticipate a steadily escalating rate of innovation in these emerging electronic disciplines beyond the dawn of the 21st century.

Emergence of a profession
Edison, Westinghouse, and other inventors and builders of electrical equipment competed to show the wonders of their new inventions. In 1881, Lucien Gaillard of France and John Gibbs of England arranged the first successful alternating-current electrical demonstration in London.
Expositions and world's fairs became popular places to showcase new inventions involving electricity. Almost as soon as they moved from the drawing board to operational status, electrical devices and systems were on display, to the delight of admiring crowds throughout the United States, England, and Europe.

Electricians were hired to build and operate these installations. The first successful use of electricity at one of these events occurred at the 1889 Paris Exposition. Four years later, the 1893 Columbian Exposition in Chicago used 10 times more electricity than the Paris Exposition. Says David E. Nye in Electrifying America (MIT Press, 1997):

"The Chicago fair employed 90,000 Sawyer-Mann incandescent lamps using alternating current, installed by Westinghouse for $5.25 each, and 5,000 arc lights installed by General Electric. To understand what these figures meant, consider that in 1890 there were only 68,000 arc lights and 900,000 incandescent lamps in the entire United States."


Columbian Exposition visitors could ride on or see electrified sites that included three cranes, elevators in some buildings, water fountains, an on-site railroad/streetcar system built by General Electric, and moving sidewalks.

Organizers of the electricity-themed 1901 Pan-American Exposition in Buffalo, N.Y., were challenged to improve on the Columbian Exposition.

Two of the Pan-American Exposition's buildings were dedicated to electricity. The 400-foot Electric Tower studded with 40,000 lights; and the Electricity Building, with a display of electrical appliances.

Meanwhile, electricity had made an appearance at the annual expositions held from 1857 to the late 1890s in St. Louis, Mo., then the fourth-largest city in the United States. The St. Louis Agricultural and Mechanical Fair took place each summer at Fairgrounds Park on the city's north side, and each winter in the Exposition and Music Hall in downtown St. Louis.

 Briner Electric Company of St. Louis opened when Charles J. Brinier founded the company in 1895. In 1897, he and his brother, Fred E. Brinier, formed a partnership-C.J. and F.E. Brinier Electric Company. In 1902, the Briers formed a separate partnership that today would be called a joint venture with William Koeneman, John Casey, and William and Louis nolker, creating Guarantee Electric Company for the specific purpose of working on the 1904 St. Louis World's Fair. After the World's Fair, William Koeneman bought out his partners to gain control of Guarantee.
Brinier Electric continued as a separate company, which the Brinier family sold in 1962 to Thomas J. Fogarty and Paul Lyons. Brinier Electric now is owned and operated by Fogarty's sons, T. Michael Fogarty, president; and his younger brother, John J. Fogarty, vice president.

 An employee, Fred J. Overtly, purchased Guarantee from the family of William Koren man in 1946. Today his sons direct Guarantee, Fred G. "Junior" Overtly, as vice chairman, and his younger brother, Charles W. "Chuck" Overtly, chairman and chief executive officer.

 Jack Aright and Theodore H. Joseph founded E-J Electric Installation Co. of New York City, in 1899. Jack Aright died in 1913. Jack Mann became Joseph's partner; today members of Mann's family le ad the company. For more information on E-J Electric, see Electrical Contractor, June 1999.

 One early contracting firm lasted to celebrate its centennial but has since gone out of business. Henry New grad & Co. of Chicago was founded in 1882. In an early advertisement, new grad described its services as "installer of electric lights, speaking tubes, electric bells, burglar alarms, and gas lighting." The firm ceased operations in the mid-1990s.
Corporate Pioneers
Following is a representative sample of the oldest power companies and manufacturers of electrical supplies:


 Siemens AG, of Munich, Germany, was the first of several companies founded by Carl, Werner, and Wilhelm Siemens. The firm was established in 1847 as Siemens & Halske OHG. Today Siemens AG is an electrical-engineering and electronics company.

 General Cable Corporation, of Highland Heights, Ky., was incorporated in New Jersey in 1927. General Cable brought together the assets of several companies formed in the 19th century, including Phillips Wire and Safety Company and George Westinghouse Standard Underground Cable Company. Companies that became part of General Cable supplied insulated cable in 1844 to Samuel Morse; wire to the Statue of Liberty in 1886 (and again in 1986), 145 miles of cable that contractors laid under New York City sidewalks in 1892, and 3,000-volt cable for Chicago's 1893 Columbia Exposition.

 Pacific Gas and Electric Co., based in San Francisco, Calif. PG&E is the result of mergers involving dozens of companies, including a number that started selling gas. As electricity became available, they sold it, too. In 1852, Peter and James Donahue founded San Francisco Gas Company, the city's first gas supplier. Oakland Gas Light, founded by John A. Britton in 1855, established a small electrical plant in 1877 and changed its name to Oakland Gas and Light Company. In June of 1879, George H. Roe formed California Electric Light Company, the first exclusively electric firm in the PG&E family of companies.

 In 1901, Britton and Roe's companies merged to form California Gas and Electric Corporation. In 1890, with the backing of J.P. Morgan, Edison started studying expansion into California. Roe went to New York and purchased the right to use Edison's patents within a 100-miles radius of San Francisco.


 Westinghouse Electric Company, one of 56 companies (including Rockwell International) founded by George Westinghouse. In 1885, Westinghouse imported a Gaylord-Gibbs transformer from England and an AC generator from Siemens Brothers, the English subsidiary of Siemens AG. He and his engineers modified this equipment and proved the economic value of his alternating-current concept over Edison's direct-current system. As an experiment, Westinghouse electrified the small village of Barrington, Mass., for two weeks in 1886.

 Westinghouse subsequently grew to become one of the world's largest companies, but it has suffered financial embarrassment and many divestitures. The firm's three remaining divisions are Westinghouse Electric Co., which provides products and services for the nuclear-power industry; The Westinghouse Government Service Co., a United States Defense Department subcontractor; and The Westinghouse Government Environmental Service Company, based in Monroe ville, Pa.

 Thomas A. Edison and a number of investors founded General Electric Light Bulb Company/Edison General Electric Company in 1887, to promote and sell electric light bulbs. In 1892, the assets of General Electric Light Bulb and other Edison companies were acquired for the newly incorporated General Electric Company. GE has made and sold many products using one or more of Edison's 1,093 American patents. "More than half of Edison's patents related to electricity," says Dr. Robert A. Rosenberg, director of the Thomas A. Edison Papers at Rutgers University in New Brunswick, N.J. "Besides the electric light bulb, Edison worked on photography (in 1877), the phonograph, the telegraph, and telephone." General Electric Company's corporate headquarters today is in Fairfield, Conn.

 Emerson Electric Manufacturing Company, founded in St. Louis in 1890 by Alexander and Charles Meston with the financial support of attorney and entrepreneur John Wesley Emerson. Still based in St. Louis, Emerson has 60 divisions and over 100,000 employees.


 
 Cutler-Hammer, founded in 1893 by Chicago inventor and business man Harry H. Cutler to manufacture manual starter boxes. The company now is part of Eaton Corporation of Cleveland.

Help More Information:

Laurence Davis, NECA: Fifty Years of Progress 1901-1951. Washington D.C.: Rufus H.
Darby Printing Co., Inc., 1951. Hard to find; made available thanks to David A. Roll, chapter manager, Western New York NECA.Davis Dyer and Jeffrey L. Cruikshank. Emerson Electric Co. A Century of Manufacturing 1890-1990. St. Louis: Emerson Electric Co., 1989.

Robert Friedel, Paul Israel, and Bernard S. Finn. Edison Electric Light Bulb. New Brunswick, N.J.: Rutgers University Press, 1987. Out of print.

Electrical Fuses

Fuses perform the same function as a breaker, except when a fuse blows, it has to be replaced.

There are cartridge fuses and screw-in fuses. Cartridges look kind of like a shotgun shell. They mount in a little rack that pulls in and out of a bracket Screw-in fuses screw in and out like light bulbs. Some have a glass window on top and metal threads on bottom.  A fuse blows; its internal metal strip breaks and the window may get discolored. Be sure to replace a fuse with the exact same amperage-rated fuse. Fifteen and 20 amp fuses are the most common size ratings. Some fuses have a smaller screw base and are called "non-tamper able, type-S" fuses. The threads vary in size so they can't be accidentally replaced by another type. When you install a fuse, screw it in snug, then give an extra 1/4-turn to make a solid connection. Other fuses are rated as "slow-blow" or "time delay." They take a little longer to blow and are made to withstand short, extra surges of power -- like a motor starting. When buying replacements, be sure to get the right fuse types. It's also a good idea to get a couple extra fuses of each type to keep on hand when working on circuits.

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Circuit Breakers

All newer homes, and many older ones that have been re-wired, will have circuit breakers. Each breaker controls the power to a group of lights, outlets and appliances.

If it hasn't been done already, you should label each breaker so you know just what it controls.
Circuit breakers protect the wiring and fixtures by turning off the power. If a fixture shorts out, or if a circuit gets overloaded, the breaker will "trip."
That cuts power to the circuit and protect the wires and fixtures from damage. The most common reason for a breaker to trip is too many appliances and lights on one circuit.
A tripped breaker usually looks like it's between the ON and OFF positions. To reset a breaker, turn it OFF and then ON again. If a service panel doesn't have breakers, it probably has fuses.

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Electrical work’s Using Testers

If working with electricity scares you, a voltage/neon-light tester can help change that. It's an inexpensive, but invaluable tool for determining if a circuit is "live" or "dead."It's basically just a small neon light bulb attached to two wires. When the contacts on the wires are touched to a live circuit, the light goes on. And when there's no juice coming to the circuit, the light stays off .But it's important to get into a good habit of always testing switches, outlets and wires before your hand actually touches them. You can test an outlet without taking off the cover plate, but also check its screw terminals. For that and for switches, you'll have to take off the cover plate .To make sure the power is off before you work on an outlet, test between the screws on each side, and between the screw on the shorter slot side and the green ground screw. No light means the "juice" is off .To check for proper grounding, test between the shorter slot (hot) and the round hole (ground). If the tester lights up, there's probably proper grounding. It should also light when you test between the shorter slot and the cover plate screw .To check that the power is off to a switch, check between both terminals on the switch and then between the copper ground lead and each terminal .For bare wires, hold one tester lead on the bare ground wire (or box if it's grounded) and the other test lead on the hot, then neutral wire. Also check between the two leads. If the light stays off, the circuit is off. Plug-in circuit testers that fit right into outlets can tell you a lot. On our tester, two amber lights mean everything's OK. Other combinations of lights indicate different potential problems with a circuit -- like an improper ground. They're handy for checking and diagnosing connections when you're installing several new cable runs and circuits.      

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Electrical System Basics

Electricity is supplied by a local utility to a house through three underground or overhead wires (two "hot" leads and one neutral lead) that enter the house through a conduit and a meter .Those wires connect to their respective buss bars inside the service panel -- usually two hot, one neutral, and one ground buss .Circuit breakers slide/snap onto the hot buss bars. They act as safeguards against short circuits and overloads by "tripping" off. A breaker also functions as a switch; turning the circuit on and off as desired .Breakers also connect to outgoing "hot" wires. The hot wires deliver power to a device (like a light) and normally have black insulation. Cable with two hot leads also have a red hot lead .Once the electricity has done it's work, it goes back to complete the circuit on the "neutral" wire, which is most often white. Electricity needs this completed circuit to work properly -- a way OUT through the hot wire, and a way BACK through the neutral wire .In addition to the neutral, the green (or bare copper) ground wire offers current another path back should an electrical short or overload happen .From the service panel, the ground has two safe paths to divert electricity: connected to a long metal rod buried outside the house and/or the house's water pipes .All the wires, called cable, are often housed by a flexible plastic sheathing. It's nonmetallic-sheathed (NM) cable, but is often mistakenly called "Romex" which is a brand name made by General Cable Corporation. Cable is also identified by gauge (thickness) and the number of leads it has. For example, NM 14-2G means that the cable is nonmetallic, 14 gauge, has two leads (1 neutral, 1 hot), and a ground wire.

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Electrical work’s Safety Steps

Before you do any electrical work on a circuit, make sure the power is off. Turn off the breaker (or pull/unscrew the correct fuse) to the circuit you'll be working on .Post a sign on the service panel so nobody tries to restore power while you're working on the circuits. Double-check the circuit with a circuit tester before you touch it to make sure the correct breaker has been tripped .Labeling or drawing a Before unhooking wires will take any guesswork out of how to reconnect them. Wear shoes with non-conductive soles, use tools with rubber grips and don't stand in water to avoid a potentially dangerous shock.Finally, never push yourself to finish a wiring job. That's when mistakes happen. If you run into a difficult stretch of work, take a break and think about what needs to be done. If you're still not sure, don't take chances -- contact a professional. 

 

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ELECTRICAL WORKS WARNING

DOING WORK WITHOUT A REQUIRED PERMIT IS NOT ONLY ILLEGAL, BUT MAY ALSO INVALIDATE YOUR HOMEOWNER'S  INSURANCE.                                                                                                      When you're doing a remodeling job, wiring may be old and outdated. If you're tearing out walls enough to expose wiring, it should be brought up to code. Obviously, that involves more work and money for materials like cable, boxes, switches, staples, but you'll feel much better having newer, safer cable in the house.                                                               

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