Household Electricity
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What is electrical power?
A measure of how fast the device transfers electrical energy. Units of electrical power are watts (W)
What is the power equation?
P = I/V Power = current (A)/voltage (V)
What is 1kWh’s signifigance in household electricity?
1kWh is amount of energy used by a 1kW appliance, switched on for an hour
How do we work out the number of kW used by an appliance?
Number of kWh/units of energy = power of appliance x time in hours
How de we work out the cost of energy used by an appliance?
Cost of energy used = number of kWh/units x cost per unit
How do we work out the total number of units of electrical energy is used by the household?
Number of units = new reading - previous reading Ignore the last number on electricity meters
What name, connection & function does the blue wire have in a plug socket?
Neutral Left terminal Returns electricity to plug socket from appliance
What name, connection & function does the brown wire have in a plug socket?
Live Right terminal Electricity enters plug & travels to appliance
What name, connection & function does the yellow/green wire have in a plug socket?
Earth Top terminal If fault develops, in appliance with metal parts, earth wire is escape route allowing electricity to flow to earth & not through someone touching appliance
How does a fuse break in a wire?
Fuse contains piece of wire that melts easily. If current going through fuse is too great, wire heat heats up until it melts & breaks circuit.
Why have fuses been replaced in recent years?
Replaced by residual circuit breakers, as they detect faults quickly
If a device works at 3A, what should be the fuse used?
5A, not 3A as fuse should be rated at slightly higher current than device needs