Official Electric Sutdy Guide Flashcards
What are the most frequent electrical citations?
- branch circuits
- Grounding Path
- Ground Fault-circuit interrupters
- Grounding live parts
- Equipment installation and use
About __ workers are
electrocuted every week.
5
Causes the deaths of __ of the
younger workforce
12%
What are the three direct electrical hazards?
- Shock, Electrical
- Electrocution or death due to electrical shock
- Burns
What are the three indirect electrical hazards?
Indirect –
- Falls
- Fires
- Explosions
An electrical shock is received when _____ passes through the body.
electrical
current
You will get
an electrical shock if a part of your body
completes an electrical circuit by…
- Touching a live wire & an electrical ground, or
- Touching a live wire & another wire at a
different voltage.
Severity of Shock - depends on:
- Path of current thru the body
- Amount of current flowing through the body (amps)
- Duration of the shocking current through the body,
___DOES NOT MEAN LOW
HAZARD!!!
LOW VOLTAGE
Hazard 1 -
Electrical Shock
Currents above __ * can
paralyze or “freeze” muscles.
10 mA
Currents more than ___ can cause a rapid, ineffective heartbeat
death will occur in a few minutes
unless a defibrillator is used
75 mA
75 mA is not much current – a small power drill uses ___ times as much.
30
mA = milliampere =
1/1,000 of an ampere
Hazard 2 -
Electrocution
Painful shocks… causing indirect accidents.
3mA+ -
Muscle contraction… “not able to let go”.
10mA+ -
Lung paralysis… usually temporary.
30mA+ -
Ventricular Fibrillation… is possible
50mA+ -
Certain Fatal Ventricular
Fibrillation
100mA to 4amp -
- Severe burns, heart paralysis.
Over 4 amps
Hazard 3 -
Burns
Most common… shock
related injury
burns
How do most people get shocked?
By touching Wires -
Touching electrical wiring or
equipment that is improperly
used or maintained
Hands get it -Typically
occurs on hands
burns
Hazard 4
Falls
Can cause Death -
Workers in elevated locations who
experience a shock may __,
resulting in serious injury or death
fall
Hazard 5
fires
most commonly caused by current flowing
through high resistance due to faulty wiring igniting
insulation and / or other material.
Fires
Heat is created from high ___ flowing through a
wire. This is analogous to two objects being rubbed together.
high currents
(At full speed, ‘skin’ of an
SST jet is about __ )
6000F
HEAT of Friction - To maintain continuity of
flow, as the diameter of a pipe decreases, the velocity of the fluid must increase, and ____.
the heat of friction increases
When a wire decreases in _____ due to damage, current must increase through that portion of the wire, & heat increases possibility to the point that surrounding materials are set on fire.
cross-sectional area
Hazard 6
Explosions
can be caused when electricity provides
the ignition source (arc) “jumping” through an air-’fuel’ mixture in the atmosphere.
Explosions
What should be used Isolate Electrical Parts.
covers,
guards
barriers
Guard live parts… of electric equipment operating at \_\_\_ or more against accidental contact
50 volts
Conductors going into live parts must be protected,
and unused openings must be closed. What do you use?
cabinets,
boxes
fittings
J-boxes (etc) must have
_____ Unused openings must be closed (no missing knockouts)
approved covers
Don’t get near power lines! watch out for what?
Cranes Ladders Scaffolds Backhoes Scissors lifts Raised dump truck beds
De-energize power lines before working on them. What are two ways this can be done?
- Lock Out/Tag Out
2. Power Provider to de-energize.
If you don’t want to de-energize power lines then:
Guard or insulate the lines