ELECTRIC SHOCKS
Lab1
Name: Mohamed Abdelhalim kassab
ID : 1900909
Section : 2
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Table of Contents
What is Electric Shocks: ......................................................................................................... 2
The types of Electric Shocks: ................................................................................................. 2
Cause of Electrical Shocks: .................................................................................................... 3
DIRECT CONTACT ............................................................................................................... 3
INDIRECT CONTACT .......................................................................................................... 3
PROTECTION AGAINST DIRECT CONTACT ................................................................ 4
PROTECTION AGAINST INDIRECT CONTACT ........................................................... 4
What is Electric Shocks:
An electric shock is a sudden discharge of electricity through the body that can cause a
range of symptoms, from mild tingling or numbness to severe burns, cardiac arrest,
and even death. The severity of an electric shock depends on the amount of current, the
duration of exposure, and the path the current takes through the body. Electric shocks
can occur from contact with live electrical wires, appliances, or machinery, or from
lightning strikes.
The types of Electric Shocks:
1. Low voltage shock: This type of shock is caused by exposure to household current or
low-voltage electrical sources such as batteries or small appliances. Symptoms include
mild tingling, numbness, or muscle contractions.
2. High voltage shock: This type of shock is caused by exposure to high-voltage
electrical sources such as power lines or electrical substations. Symptoms can be severe
and include burns, cardiac arrest, and even death.
3. Arc flash: This type of shock occurs when an electrical current jumps from one
conductor to another, creating a bright flash of light and intense heat. Arc flash can
cause severe burns and other injuries.
4. Lightning strike: This type of shock occurs when a person is struck by lightning,
which can cause a range of symptoms including burns, cardiac arrest, and even death.
It is important to take precautions to avoid electric shocks, such as avoiding contact
with live electrical wires, using electrical equipment properly, and wearing appropriate
protective gear when working with electricity. If you do experience an electric shock,
seek medical attention immediately.
Cause of Electrical Shocks:
DIRECT CONTACT
Electric shock results from contact with a conductor, i.e. an energised conductor being
a part of a circuit. An example: someone removing a cover from the electrical switch
and touching the wires inside. It may also occur as a result of damage to the wire
insulation. In this case, overvoltage protection systems do not provide any protection,
but a residual-current circuit breaker with an operating current of up to 30mA may do
so.
INDIRECT CONTACT
Electric shock from indirect contact occurs when an object that should not be energised
becomes such e.g. due to a failure (insulation damage) or a faulty electrical installation.
In this way, contact with outer cases, mounting/fixing parts or switches may pose a
hazard. People at the highest risk of such shock are electric technicians and engineers.
PROTECTION AGAINST DIRECT CONTACT
The safeguards for preventing direct contact are mainly intended to minimise the
possibility of touching energised wires. These safeguards include:
1. Insulation of energised parts – this is a standard procedure. Wires are often
double-insulated, and the insulation is additionally strengthened to improve the
resistance to temperature fluctuation or bending.
2. Providing physical barriers or casings protecting against contact (IP2X) – where
surfaces are horizontal and available, IP4X protection applies (excluding solids
wider than 1 mm).
3. Placing a wire out of reach or providing barriers preventing people from
reaching the energised (live) parts. For this purpose, various types of barriers,
cabinets or safety nets are used.
4. RCD breakers provide additional protection, but only if the contact is from a live
(energised) part to an earthed part.
PROTECTION AGAINST INDIRECT CONTACT
There are three safeguards providing protection against shock from contact with a
conductor or component that should not be energised under normal conditions:
1.Making sure that a failure resulting in the parts becoming energised will cause a
power cut-off within a safe time limit. In practice, this involves reducing the earth fault
loop impedance.
2.Using an RCD breaker that cuts off the power supply in the event of a residual
(leakage) current.
3.Using a local, supplementary equipotential bonding to ensure that the resistance
between parts that can be touched simultaneously is so low that no dangerous potential
difference can occur between them. Note that although such precautions eliminate the
danger of indirect contact, it is still necessary to make sure that the power supply is
disconnected in order to provide protection against other faults, such as overheating.
4.Sometimes, the dangerous voltage can be maintained, if an uninterruptible power
supply (UPS) or a backup generator with an automatic start-up is used.