SP6g Electricity in the home Flashcards
Explain direct current (dc).
in cells, batteries and solar cells the direction of movement of charge is from the negative to positive terminal of the battery.
Explain alternating current (ac).
mains electricity is produced using generators that rotate, causing the direction of the current to keep changing.
What colour is the live wire?
brown.
What colour is the neutral wire?
blue.
What colours is the earth wire?
yellow and green.
Earth wire?
connects the metal parts of the appliance to a large metal spike pushed in the ground for safety - at 0V
Live wire?
connects the appliance to the generators at the power station - at 230V
Neutral wire?
the return path to the power station - at 0V
Fuse?
sacrificial safety device marked with the current it can carry.
What may happen if a faulty appliance draws too much current?
it can cause overheating of the wiring or the appliance - this causes fires.
Explain what a fuse does.
.if a current exceeds a certain value, the wire in a fuse melts
.this breaks the circuit and stops the current
.once the fault is fixed a new fuse must be fitted
Explain why you should not fit a fuse that has too high a fuse rating.
it will not stop an unsafe current at a low enough value.
Explain why you should not fit a fuse that has too low a fuse rating.
it will keep blowing when the current is safe and will have to be replaced.
What are residual current circuit breakers?
RCCB’s are a type of automatic switch that stops current flowing if there is a problem in the circuit. These work very quickly, so can save lives.
