Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

safety test 2 > 23 September > Flashcards

23 September Flashcards

1
Q

About how many workers are electrocuted every week?

A

5 workers

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What percent of worker occupational deaths are caused by electricity?

A

electricity causes 12% of young worker occupational deaths

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

4 main types of electrical injuries: direct and indirect

A 
Direct:
   - electrocution or death due to electrical shock
   - electrical shock
   - burns
Indirect:
   - falls
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Levels of dangers of currents

A
  • 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
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

old saying about voltage and current

A

voltage hurts, current kills

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

what is the most common shock related injury?

A

burns

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Burns:

A
  • occur when you touch electrical wiring or equipment that is improperly used or maintained
  • very serious injury that needs immediate attention
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

how does electricity work

A
  • electricity is the flow of energy from one place to another
  • requires a source of power - usually a generating station
  • a flow of electrons (current) travel through a conductor
  • travels in a closed circuit
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

voltage definition

A

voltage is the fundamental force or pressure that causes electricity to flow through a conductor and is measured in volts

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

resistance definition

A

resistance is anything that impedes the flow of electricity through a conductor and is measured in ohms

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

definition of current

A

current is the flow of electrons from a source of voltage through a conductor and is measured in amperes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Alternating Current (AC) definition

A
  • the current flows back and forth (a cycle) through a conductor
  • in each cycle, the electrons flow first in one direction, then the other
  • normal rate is 60 Hz
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Direct Current (DC) definition

A

the current flows in one direction only (as in a car battery)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

is AC or DC used more often, and why?

A

AC is most widely used b/c it is possible to step up or step down the current through the transformer

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Ohm’s Law

A

current = voltage / resistance

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Ground (definition)

A

a conducting connection, whether or not unintentional, between an electrical circuit or equipment and the earth, or to some conducting body that serves in place of the earth

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

electrical shock definition

A
  • an electrical shock is received when electrical current passes through the body
  • you will get an electrical shock if a part of your body completes an electrical circuit by:
    • touching a live wire and an electrical ground, OR
    • touching a live wire and another wire at different voltage
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

shock severity depends on:

A
  • path of current through the body
  • amount of current flowing through the body (amps)
  • duration of the shocking current through the body
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

what is the “let go” threshhold of current?

A

10 - 15 mA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

3 principle ways that people experience shock:

A
  1. contact with a normally energized bare conductor (close proximity with a high voltage conductor is often enough)
  2. contact with a normally insulated conductor that the insulation has deteriorated or has been damaged
  3. equipment failure: results in an open or short circuit, causing the current to flow in an unwanted manner
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

4 basic ways insulation may fail

A
  1. mechanically - as with friction, tearing, crushing, or animal attack
  2. excessive electrical stress - occurs when the equipment and/or wiring experiences currents significantly beyond what it is designed for
  3. temperature - excessive high or low temps, or temp cycling can cause differential expansion or contractions on the insulator
  4. chemical and physical reaction - oxidation, contamination, or leaching of important ingredients from the insulation
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

electrical accidents are caused by a combination of what 3 factors

A
  • unsafe equipment and/or installation
  • workplaces made unsafe by the environment
  • unsafe work practices
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

control of electrical hazards: isolate electrical parts:

A
  • use guards or barriers (guard live parts of electric equipment operating at 50 volts or more against accidental contact - SESEK DOESNT LIKE THIS B/C CURRENT HURTS YOU MORE)
  • replace covers
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

control of electrical hazards - isolate electrical parts - cabinets, boxes, and fittings

A

conductors going into them must be protected, and unused openings must be closed

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

control of electrical hazards - close openings

A
  • junction boxes, pull boxes, and fittings must have approved covers
26
Q

hazard - overhead powerlines

A
  • usually not insulated
  • examples of equipment that can contact power lines: crane, ladder, scaffold, backhoe, scissor lift, raised dump truck, aluminum paint roller, child retrieving knife with bamboo pole and razor blade
27
Q

control - overhead power lines

A
  • stay atleast 10 ft away
  • post warning signs
  • assume that lines are energized
  • use wood or fiberglass ladders, not metal
  • power line workers need special training and PPE
28
Q

hazard - inadequate wiring

A
  • hazard: wire to 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
29
Q

control of inadequate wiring

A
  • use the correct wire
  • wire used depends on operation, building materials, electrical load, and environmental factors
  • use fixed cords rather than flexible cords
  • use correct extension cord
30
Q

hazard - defective cords and wires

A
  • plastic or rubber covering missing

- damaged extension cords and tools

31
Q

cords can be damaged by:

A
  • aging
  • door or window edges
  • staples or fastenings
  • abrasion from adjacent materials
  • activity in the area
32
Q

control - cords and wires

A
  • insulate live wires
  • check before use
  • use only cords that are 3-wire type
  • use only cords marked for hard or extra hard usage
  • use only cords, connection devices, and fittings equipped with strain relief
  • remove cords by pulling on the plug, NOT the cords
  • cords not marked for hard or extra hard use, or which have been modified, must be taken out of service immediately
33
Q

permissible use of flexible cords - do not use flexible wiring when.. and flexible cords must not be…

A
  • do not use flexible wiring where frequent inspection would be difficult or where damage would be likely
  • flexible cords must not be:
    • run through holes in walls, ceilings, or floors
    • run through doorways, windows, or similar openings (unless physically protected)
    • hidden in walls, ceilings, floors, conduit or other raceways
34
Q

Grounding creates what and how does it protect you

A
  • grounding creates a low-resistance path from a tool to the earth to dispense unwanted current
  • when a short or lighting occurs, energy flows to the ground, protecting you from electrical shock, injury, and death
35
Q

hazard - improper grounding

A
  • tools plugged into improperly grounded circuits may become energized
  • broken wire or plug on extension cord
  • some of the most frequently violated OSHA standards
36
Q

control - ground tools and equipment

A
  • ground power supply systems, electrical circuits, and electrical equipment
  • frequently inspect electrical systems to insure path to ground is continuous
  • inspect electrical equipment before use
  • don’t remove ground prongs from tools or extension cords
  • ground exposed metal parts of equipment
37
Q

Control - use GFCI

A
  • ground fault circuit interrupter
  • protects you from shock
  • detects difference in current between black and white wires
  • if a ground fault is detected, GFCI shuts off electricity in 1/40th of a second
  • use GFCI’s on all 120 volt, single-phase, 15- and 20- ampere receptacles, or have an assured equipment grounding program
38
Q

control - assured equipment grounding conductor program

A
  • program must cover: all cord sets, receptacles not part of a building or structure, and equipment connected by plug and cord
  • program requirements include: specific procedures adopted by employer, competent person to implement the program, and visual inspection for damage of equipment connected by cord and plug
39
Q

hazard - overloaded circuits - hazards may result from…

A

hazards may result from:

  • too many devices plugged into a circuit, causing heated wires and possible fire
  • damaged tools overheating
  • lack of over-current protection
  • wire insulation melting, which may cause arcing and a fire int he area where the overload exists, even inside a wall
40
Q

Breakers and Fuses protection vs. GFCI protection

A
  • breakers and fuses protect equipment, and your overall system from a fire, they dont protect people (by the time they melt or pop, youre melted or popped first)
  • a GFCI is intended to protect people
41
Q

control - electrical protective devices

A
  • automatically opens circuit if excess current from overload or ground-fault is detected - shutting off electricity
  • includes GFCI’s, fuses, and circuit breakers
42
Q

fuses and circuit breakers are:

A

overcurrent devices - when too much current:

  • fuses melt
  • circuit breakers trip open
43
Q

power tool requirements

A
  • have a three-wire cord with ground plugged into a grounded receptacle, or
  • be double insulated, or
  • be powered by a low voltage isolation transformer
44
Q

tool safety tips

A
  • use gloves and appropriate footwear
  • store in dry places when not using
  • dont use in wet/damp conditions
  • keep working areas well lit
  • dont carry tool by cord
  • remove damaged tools from use
  • dont yank cords to disconnect
  • keep cords away from heat, oil, and sharp edges
  • disconnect when not in use and when changing accessories such as blades/bits
  • ensure cords are not a tripping hazard
45
Q

preventing electrical hazards in tools

A
  • inspect tools before use
  • use the right tool, correctly
  • protect tools
  • use double insulated tools
46
Q

double insulated tools

A
  • hand-held tools manufactured with non-metallic cases are called double insulated
  • if approved, they do not require grounding under the National Electric Code
  • although this design method reduces risk of grounding deficiencies, a shock hazard can still exist
47
Q

temporary lights

A

protect from contact and damage, and dont suspend by cords unless designed to do so

48
Q

clues that electrical hazards exist

A
  • tripped circuit breakers or blown fuses
  • warm tools, wires, cords, connections, or junction boxes
  • GFCI that cuts off a circuit
  • worn or frayed insulation around wire or connection
49
Q

lockout and tagout of circuits

A
  • apply locks to power sources 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
50
Q

to protect workers from electrical shock:

A
  • use barriers or guards to prevent passage through areas of exposed energized equipment
  • pre-plan work, post hazard warnings and use protective measures
  • keep working spaces and walkways clear of cords
51
Q

other safety-related work practices

A
  • use special insulated tools when working on fuses with energized terminals
  • dont use worn or frayed cords/cables
  • dont fasten extension cords with staples, hang from nails, or suspend wire
52
Q

preventing electrical hazards - planning

A
  • plan work with others
  • plan to avoid falls
  • plan to lock-out and tag-out equipment
  • remove jewelry
  • avoid wet conditions
  • avoid overhead power lins
53
Q

why to avoid wet conditions

A
  • if you touch a live wire or other electrical component while standing in even a small puddle, youll get a shock
  • damaged insulation, equipment, or tools can expose you to live electrical parts
  • improperly grounded metal switch plates and ceiling lights are especially hazardous in wet conditions
  • wet clothing, high humidity, and perspiration increase chances of being electrocuted
54
Q

preventing electrical hazards - PPE

A
  • proper foot protection (not tennis shoes)
  • rubber insulating gloves, hoods, sleeves, matting, and blankets
  • hard hat (insulated - nonconductive)
55
Q

preventing electrical hazards - proper wiring and connectors

A
  • use and test GFCI’s
  • check switches and insulation
  • use 3 prong plugs
  • use extension cords only when necessary and assure in proper condition and right type for job
  • use correct connectors
56
Q

training

A
  • de-energize electric equipment before inspecting or repairing
  • use cords, cables, and electric tools that are in good repair
  • lockout/tagout recognition and procedures
  • use appropriate PPE
57
Q

electrical fires - 3 principle ways in which electrical installations could cause fires

A
  • electrical overloading
  • electrical discharges (sparcs, arcs, or coronas)
  • electrical heating appliances
58
Q

electrical overloading

A
  • current in circuit is greater than design levels
  • excess current generates excess heat
  • heat damages components
  • may ignite flammable nearby materials, including insulation
  • a fuse “blowing” or a circuit breaker “popping/snapping” means theres a problem
59
Q

electrical discharges (sparcs, arcs, or coronas)

A
  • spark: a rapid, heavy discharge of electrons. occurs any time an ionized path develops in the dielectric medium separating 2 conductors or a conductor and ground
  • arc: a sustained stream of electrons flowing across a gap between conductors that were initially in contact or close together while current is flowing
  • corona: occurs in high-voltage systems when the dielectric medium separating conductors partially breaks down (the potential difference reaches a level necessary to ionize gas in the dielectric medium, but not enough to produce a spark - produces faint glow in dark)
  • may ignite flammable solid, liquid, vapors, dust, or powders
  • electrical devices may need to be in explosion proof enclosures
  • may cause electrical noise and interfere with electrical equipment
  • spark caused by static electricity can cause fires in certain environments
60
Q

electrical heating appliances

A
  • commonplace both at home and in workplace
  • not appropriate where flammable materials or atmosphere are expected
  • may cause burns to person that makes contact with equipment

safety test 2 (8 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions