mech hzards

8/12/2019 Mech Hzards

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DEFINITION

A physical agency caused by themotion of electrons, protons, and othercharged particles, manifesting itself asan attraction, repulsion, magnetic,

luminous, and heating effects, etc.


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ELE ENT! " ATO !

E#ery $no%n substance & solid, li'uid orgas is composed of elements

An atom is the smallest particle of anelement that retains all the properties ofthat element

Each element has it(s o%n $ind of atom


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ATO !

Each element has a definite number ofelectrons ++++and the same number of

protons

They are oppositely charged andtherefore attract each other. This tendsto hold the electrons in orbit around theatom.


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F-EE ELE T-ON!

!ome atoms are easily mo#ed out of orbit

The ability to mo#e or flo% is the basis ofcurrent electricity

If channeled in a gi#en direction, a flo% ofelectrons occurs +++ %hen flo%ed through aconductor it is # "a ic electricit


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ELE TI AL ATE-IAL!

OND0 TO- & contains many free

electrons +++ gold, copper, sil#er,aluminum

IN!0LATO- & contains fe% freeelectrons+0sually non+metallic such as%ood, rubber, glass, etc


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1ENE-ATIN1 ELE T-I IT

Friction, pressure, heat, light, chemicalreaction, and magnetism

agnetism is most practical " ine2pensi#emethod

Electricity is produced %hen a magnet ismo#ed past a piece of %ire, or %ire ismo#ed through a magnetic field


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3OLTA1E, 0--ENT, "-E!I!TAN E

3OLTA1E & unit of measurement of electromoti#eforce 4E F5

0--ENT + ontinuous mo#ement of electrons pasta gi#en point. 4measured in amperes5

-E!I!TAN E & Opposition to mo#ement of electrons.a$es it possible to generate heat, control current

flo%, " supply correct #oltage to de#ices


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O6 (! LA7

1eorge !imon OhmFormulated a mathematical relationship bet%een8

urrent3oltage-esistance

-esistance * Impedance-esistance * DImpedance * AInterchangeable & ost /ranch circuits


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DI-E T 0--ENT

Al%ays flo%s in one direction

0sed to charge batteries, run somemotors, operate magnetic lifting de#icesand %elding e'uipment.


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ALTE-NATIN1 0---ENT

ore common in electrical %or$

hanges rapidly in both direction and#alue

)o%er companies produce po%ercheaper %ith alternating current


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ELE T-I AL 6A9A-D!S/ & . Electric s$!c !ccurs $e"t$e $u a" b!# bec! es part !f t$epat$ t$r!ug$ $ic$ curre"t fl! s.

$e #irect result ca" beelectr!cuti!".

$e i"#irect result ca" be i" ur

resulti"g fr! a fall !r !ve e"ti"t! ac$i"er because !f a s$!c


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ELE T-I AL 6A9A-D!6* 8S. 6ur"s ca" result $e" a pers!"t!uc$es electrical iri"g !r e uip e"tt$at is e"ergi:e#.

, &-6L,S . ,rc-blasts !ccur fr! $ig$-a perage curre"ts arci"g t$r!ug$ t$eair. $is ca" be cause# b acci#e"talc!"tact it$ e"ergi:e# c! p!"e"ts !re uip e"t failure.


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Arc Flash and Arc /lasts

Arc Flash8:;,;;;FFatal /urns+?; ft.

@;;; peoplehospitali ed %ithburns

olten metal

Arc /last8)ressure 7a#e

6eatolten metalDestruction ofstructures and life


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Arc /last

ause!hort ircuit caused by %or$ing on

energi ed e'uipmentDropped Tool

Occurs in milliseconds

Temp8 =;,;;; degrees Air e2pands #ery #iolently?> tons of pressure


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ELE T-I AL 6A9A-D!

, &-6L,S . $e t$ree pri ar$a:ar#s ass!ciate# it$ a" arc-blast

are$er al ra#iati!".;ressure


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ELE T-I AL 6A9A-D!

E=;L S> 8S. E%pl!si!"s !ccur$e" electricit pr!vi#es a s!urce !f

ig"iti!" f!r a" e%pl!sive i%ture i"t$e at !sp$ere.


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ELE T-I AL 6A9A-D!

> ES. Electricit is !"e !f t$e !stc! !" causes !f fires b!t$ i" t$e

$! e a"# i" t$e !r place.?efective !r isuse# electricale uip e"t is a a !r cause.


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EFFE T! ON T6E 60 AN /OD

?epe"#s !"&urre"t a"# @!ltage

esista"ce;at$ t$r!ug$ b!#?urati!" !f s$!c


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Effects of A Electricity

ore than = mA+ )ainful shoc$+ causeindirect accident

ore than ?; mA+ uscle contraction &BNo Let 1oC danger

ore than =; mA+ Lung paralysis,

usually temporary


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Effects of A Electricity

ore than >; mA+ 3entricularfibrillation, usually fatal

?;; mA to A+ ertain #entricularfibrillation, fatalO#er A+ 6eart paralysis, se#ere burns


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Effects

)rotectionircuit /rea$ers

Fuses?> or @; amps)roperty e'uipment protection


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onductors

American 7ire 1auge?@ gauge & @; amps 4!afely5

? gauge & ?> amps?; gauge & =; amps

7hat determines amount of ampsthrough a circuit

6o% much the e'uipment dra%s6o% much BstuffC plugged in


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>#e"tificati!"A Splices a"#er i"ati!"s

Fle2ible cords shall only be used in

continuous lengths, no taps or splices

?a age# c!r#i pr!perl repaire#


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Fle2ible cords shall be connected to de#ices

and fittings so that strain relief is pro#ided

%hich %ill pre#ent pull from being directly

transmitted to Goints or terminal scre%s

>#e"tificati!"A Splices a"#er i"ati!"s


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1910.332 rai"i"g!cope8

The training re'uirements contained in this section

apply to employees %ho face a ris$ of electric shoc$

that is not reduced to a safe le#el by the electricalinstallation re'uirements of ?H?;.=;= through

?H?;.=;:

Employees shall be trained in and familiar %ith thesafety+related %or$ practices re'uired by ?H?;.==?

through ?H?;.==> that pertain to their respecti#e Gob

assignments


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4b54=5Qualified persons: 4i.e. those permittedto %or$ on or near e2posed energi ed parts5shall, at a minimum, be trained in and familiar%ith the follo%ing8

4i5 The s$ills and techni'ues necessary to#isti"guis$ e%p!se# live parts from other parts ofelectric e'uipment

4ii5 The s$ills and techni'ues necessary to#eter i"e t$e "! i"al v!ltage of e2posed li#eparts4iii5 The cleara"ce #ista"ces specified in?H?;.===4c5

1910.332 rai"i"g


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1910.333 (a)(1) ?ee"ergi:e#parts

Li#e parts to %hich an employee may bee2posed shall be deenergi ed beforethe employee %or$s on or near them8

0nless the employer can demonstrate thatdeenergi ing introduces additional orincreased ha ards or is infeasible

Li#e parts that operate at less than >; #oltsto ground need not be deenergi ed if there%ill be no increased e2posure to electricalburns or to e2plosion due to electric arcs


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1910.333(b)

4?5 onductors and parts of electric e'uipment

that ha#e been deenergi ed but ha#e not been

loc$ed out or tagged in accordance %ith

paragraph 4b5 of this section shall be treated as

energi ed parts


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1910.333(c)(4) >llu i"ati!"

Employees may not enter spaces containinge2posed energi ed parts, unless illumination is

pro#ided that enables the employees to

perform the %or$ safely


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1910.333(c)(4) >llu i"ati!"

Employees may not

reach blindly intoareas %hich may

contain energi ed

parts.


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1910.333(c)(7) ;!rtable la##ers

)ortable ladders shall ha#e nonconducti#e

siderails if they are used %here the employee

or the ladder could contact e2posedenergi ed parts


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1910.334 *se !f e uip e"t

)ortable e'uipment shall be handled ina manner %hich %ill not cause damage

Fle2ible electric cords connected to

e'uipment may not be used for raisingor lo%ering the e'uipment

Fle2ible cords may not be fastened %ithstaples or other%ise hung in such afashion as could damage the outer

Gac$et or insulation


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1910.334 (a)(2)(i) *se !f e uip e"t)ortable cord and plug connected e'uipment

and fle2ible cord sets 4e2tension cords5visually inspected before use for externaldefects 4such as loose parts, or damage to

outer Gac$et or insulation5 and for e#idence ofpossible internal damage 4pinched or crushedouter Gac$et5

E2tension cords %hich remain connected oncethey are put in place and are not e2posed todamage need not be #isually inspected untilthe are relocated


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1910.334 *se !f e uip e"t

A fle2ible cord used %ith grounding type e'uipmentshall contain an e'uipment grounding conductor

Attachment plugs and receptacles may not beconnected or altered in a manner %hich %ouldpre#ent proper continuity of the e'uipment groundingconductor at the point %here plugs are attached toreceptacles


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1910.334 (c)(1) *se

Only ualifie# pers!"s may perform testing%or$ on electric circuits or e'uipment

1910 334 * !f i "t


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1910.334 *se !f e uip e"t

4c54@5 3isual inspection. Test instruments and

e'uipment and all associated test leads,cables, po%er cords, probes, and connectorsshall be #isually inspected for e2ternal defects

and damage before the e'uipment is used.If there is a defect or e#idence of damage thatmight e2pose an employee to inGury, the

defecti#e or damaged item shall be remo#edfrom ser#ice, and no employee may use it untilrepairs and tests necessary to render the

e'uipment safe ha#e been made.


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1910.335 Safeguar#s f!r pers!""elpr!tecti!"

4a54?54ii5)rotecti#e e'uipment shall bemaintained in a safe, reliable condition andshall be periodically inspected or tested, asre'uired by ?H?;.?=J K

+1910.137 Electrical pr!tective e uip e"t


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4a54@54i57hen %or$ing near e2posed energi edconductors or circuit parts, each employeeshall use insulated tools or handling e'uipmentif the tools or handling e'uipment might ma$econtact %ith such conductors or parts


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4b5The follo%ing alerting techni'ues shall beused to %arn and protect employees from

ha ards %hich could cause inGury due toelectric shoc$, burns, or failure of electrice'uipment parts8

!afety signs and tags/arricades

Attendants


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4b54?5!afety signs, safety

symbols, or accident

pre#ention tags shall beused %here necessary to

%arn employees about

electrical ha ards %hich

may endanger them, as

re'uired by ?H?;.? >


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4b54@5/arricades shall be used in conGunction%ith safety signs %here it is necessary to

pre#ent or limit employee access to %or$ arease2posing employees to uninsulated energi edconductors or circuit parts


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If signs and barricades do not pro#ide

sufficient %arning and protection from electrical

ha ards, an attendant shall be stationed to%arn and protect employees


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