P4.4 - electrical safety Flashcards
what is the heating effect of current?
what is / what is the hazard of damaged insulation?
-coating is disturbed, metal part is exposed
-if touched without an insulator coating, person gets shocked
-open to water, can meet with water
-current can flow through other metallic things when in contact
why does the outer casing of an electrical appliance be non conducting (double insulated) or earthed?
someone can get shocked when touching it otherwise
what is the hazard of overheating cables?
excess of current –> hot –> melt / can catch fire
use of fuses?
when the current is overheated, fuse breaks (blows out) so it breaks the circuit before the current can reach the appliance so the appliance is safe
what is / what is the hazard of damp conditions?
presence of excessive moisture/water
water is a conductor so
-short circuit can catch fire
-long circuit flows to the earth and can electrocute a person
what is the hazard of excess current from overloading of : plugs, extension leads, single/multiple sockets - when using a mains supply?
if too many appliances are connected to one socket, overheating can occur which can lead to fire
what is a fuse?
thin section of wire designed to melt and break if the current gets above a certain value
what is a trip switch?
safety device designed to cut off the flow of electricity to an appliance if the current is too large
use of trip switch?
when current exceeds a certain value, switch trips and break the circuit
different between trip switch and fuse?
trip switches are reusable and can be used multiple times while a fuse is only a one-time use
what is earthing used for?
protects user from electric shock when electricity is leaking from the appliance
live wire meaning
wire that always carries current
carries alternating current from the mains supply to the circuit
neutral wire meaning
takes current away (load –> source)
form the opposite ends of the circuit to the live wire to complete the circuit
earth wire meaning?
carries leaks (current –> earth)
safety wire so that the wire doesn’t become live
