Electrical Safety Sc Folio

Electrical Safety

SCIENCE FOLIO

Dangerous of electric shock

 An electric shock happens when an electric current passes through
your body. This can burn both internal and external tissue and cause
organ damage.

 A shock can cause muscle spasms
 A shock can cause cardiac arrest
 A shock can cause burns to tissues and organs
 A shock can affect the nervous system
 A shock can have other unexpected consequences

Types of electric shock – directly and
indirectly

Directly Indirectly

• This refers to a person coming into contact • This refers to a person coming into contact

with a conductor which is live in normal with an exposed conductive-part which is

circumstances. not normally live, but has become live

• The protection to be implemented in these accidentally (due to insulation failure or

circumstances is called "Basic Protection some other cause).

• The protection to be implemented

in these circumstances

is called

"Fault Protection".

Risk of electric shock – skin burn, fire

Skin Burn :

 When a current above 100 mA passes through the body, it leaves marks at the points of
contact with the skin. Currents above 10,000 mA (10 A) cause serious burns that may require
amputation of the affected limb.

 Some burns are easy to recognize because they look like the burns you can get from contact
with heat. Others may seem harmless but aren’t: tiny charred craters indicate the presence of
much more serious internal burns.

Fire :

 Electrical overloads. When there’s a rise in current that exceeds the capacity of the cable it will
cause it to overheat which can, in turn, cause a fire.

 Short circuits. When contact inadvertently happens between two conductors the current will
take the ‘shortest’ route, from one to the other, without traveling through the rest of the circuit.

 Leakage current. When electrical insulation becomes degraded, or where there is excessive
moisture or corrosion present, electrical current can leak towards earth ground or neighboring
conductive elements.

 Lightning. A typical bolt of lightning carries an electric current of 30,000 amperes (30 kA). If such
a discharge travels along a power line to a facility, or if a facility is struck directly by lightning, it
can cause a massive fire hazard.

How to protect from electric shock

– device, precaution

 Inspect electric cords for fraying. If you see a crack in the
insulation, repair or replace it. Cords can be frayed if they get
moved a lot, are in the sun, or are chewed by an animal, or if
you have had them for a long time.

 Do not plug too many things into the same outlet. This can
overload electrical circuits.

 Keep all electric appliances away from places where there is
water, such as a sink, toilet, or bathtub. Do not handle
extension cords or electric appliances and do not plug
anything into an electrical outlet when your hand is wet or if
the appliance is on a wet surface.

 Stay clear of electric power lines when you are trimming trees
or using gardening tools.