Electricity 4.4 ————
Danger of electricity
- Electric shock - when electricity or current flows through your body to the earth/ground.
What controls the flow of electricity :
- Size of current which flow - If it’s big, it’ll be a worse electric shock
- Length of time - If it’s long, it could damage the human body
- Where did it happen - Some parts of the body like ‘eyes’ are more vulnerable to electric
shock.
Human body
Current that humans can withstand is around 100 mA so if it’s around 100 - 200 mA, it may cost death.
Humans are made of dry skin with resistivity ( high ). This resistivity helps the human from a large
current to kill them; however, the resistivity can be lowered if the human is in a damp condition.
So, if a human is in a damp condition, it can lower the resistivity and make it easier for current to pass
through.
Damp Conditions
It increases the chance of getting an electric shock.
- > Hair dryer in wet sink/tub is really dangerous because water lowers the resistance for the
current’s path to go back to earth.
WAYS TO INCREASE RESISTANCE In this scenario
- Wearing insulator items like shoes
- Standing on the ground.
Damaged Insulator
1) When a wire is damaged, or long and open for people to step on. The wire will eventually be
damaged causing it to cause a fire, and electric shock.
2) This can also happen with overloading of plugs, too much appliance connecting in a circuit and
OVERHEATING of cables -> large amounts of heat generated can melt the insulator and cause a
fire.
TO PREVENT electrical shocks/accidents
- Do not put too much appliance in a circuit
- Use an insulator like plastic/wood
- Do not touch with damp hands or put appliance near water
- Do not step on long wires
- Use an earth pin
Fire Risk
Danger of electricity
- Electric shock - when electricity or current flows through your body to the earth/ground.
What controls the flow of electricity :
- Size of current which flow - If it’s big, it’ll be a worse electric shock
- Length of time - If it’s long, it could damage the human body
- Where did it happen - Some parts of the body like ‘eyes’ are more vulnerable to electric
shock.
Human body
Current that humans can withstand is around 100 mA so if it’s around 100 - 200 mA, it may cost death.
Humans are made of dry skin with resistivity ( high ). This resistivity helps the human from a large
current to kill them; however, the resistivity can be lowered if the human is in a damp condition.
So, if a human is in a damp condition, it can lower the resistivity and make it easier for current to pass
through.
Damp Conditions
It increases the chance of getting an electric shock.
- > Hair dryer in wet sink/tub is really dangerous because water lowers the resistance for the
current’s path to go back to earth.
WAYS TO INCREASE RESISTANCE In this scenario
- Wearing insulator items like shoes
- Standing on the ground.
Damaged Insulator
1) When a wire is damaged, or long and open for people to step on. The wire will eventually be
damaged causing it to cause a fire, and electric shock.
2) This can also happen with overloading of plugs, too much appliance connecting in a circuit and
OVERHEATING of cables -> large amounts of heat generated can melt the insulator and cause a
fire.
TO PREVENT electrical shocks/accidents
- Do not put too much appliance in a circuit
- Use an insulator like plastic/wood
- Do not touch with damp hands or put appliance near water
- Do not step on long wires
- Use an earth pin
Fire Risk
