UK mains Electrical safety
The average UK plug supplies 230V Plastic insulation
at 50Hz of alternating current o prevents people from getting an electric shock.
UK plugs o Wires have 2 layers of insulation (inner and
outer) made of PVC because it is flexible and
doesn’t conduct electricity so is safe to touch
Double insulation
o Any appliance with a plastic casing can’t become
live so don’t need an earth wire
o Some appliances have metal casing but have
insulator sprayed on the inside
Damaged insulation
o can lead to bare wires and lead to electric shocks
Overloading cables
o Results in lots of current flowing through the
Safety features
wires and they can overheat, melt and possibly
The earth pin is longer than the start a fire
other 2 so the appliance is earthed Damp conditions
before current starts to flow so if o are dangerous because water is ionising and can
there’s a short circuit the appliances conduct electricity and cause a short circuit
will immediately shut off so there is The earth wire
no risk of electrocution o carries no current and is for safety purposes only
Cable grip prevents wires from o it prevents the casing from becoming live by
coming out providing a low resistance path to earth creating
a short circuit and causing the current to become
Forces extremely high so the fuse melts and circuit stops
RCCB
Kinetic energy depends on mass and o a residual current circuit breaker
velocity o if the current through the circuit is too high an
electromagnetic switch will break the circuit
Fuses
o always connected to the live wire
o added to a circuit to limit the amount of current
flowing through a circuit
o if the current is too high the fuse will melt and
break the circuit
Speed = distance ÷ time o most common fuses 3A and 13A
Stationary object or travelling at a
Fuse RCCB
constant velocity = no resultant
Very cheap More expensive
force (all acting forces are equal and
Needs to be replaced Can just be switched
opposite) Take a second to melt Switches off immediately with
Gravitational potential energy no delay
depends on the mass of the object
and how high you lift it
The average UK plug supplies 230V Plastic insulation
at 50Hz of alternating current o prevents people from getting an electric shock.
UK plugs o Wires have 2 layers of insulation (inner and
outer) made of PVC because it is flexible and
doesn’t conduct electricity so is safe to touch
Double insulation
o Any appliance with a plastic casing can’t become
live so don’t need an earth wire
o Some appliances have metal casing but have
insulator sprayed on the inside
Damaged insulation
o can lead to bare wires and lead to electric shocks
Overloading cables
o Results in lots of current flowing through the
Safety features
wires and they can overheat, melt and possibly
The earth pin is longer than the start a fire
other 2 so the appliance is earthed Damp conditions
before current starts to flow so if o are dangerous because water is ionising and can
there’s a short circuit the appliances conduct electricity and cause a short circuit
will immediately shut off so there is The earth wire
no risk of electrocution o carries no current and is for safety purposes only
Cable grip prevents wires from o it prevents the casing from becoming live by
coming out providing a low resistance path to earth creating
a short circuit and causing the current to become
Forces extremely high so the fuse melts and circuit stops
RCCB
Kinetic energy depends on mass and o a residual current circuit breaker
velocity o if the current through the circuit is too high an
electromagnetic switch will break the circuit
Fuses
o always connected to the live wire
o added to a circuit to limit the amount of current
flowing through a circuit
o if the current is too high the fuse will melt and
break the circuit
Speed = distance ÷ time o most common fuses 3A and 13A
Stationary object or travelling at a
Fuse RCCB
constant velocity = no resultant
Very cheap More expensive
force (all acting forces are equal and
Needs to be replaced Can just be switched
opposite) Take a second to melt Switches off immediately with
Gravitational potential energy no delay
depends on the mass of the object
and how high you lift it
