wiring a plug...let's just say i'm curious?

Question

why are the wires in a plug covered in flexible plastic?
why is brass used to make the pins in the plug?
why is the earth pin longer than the others?
why is thick cable used for some appliances and thin for others?
what is the purpose of a fuse?

Answer 1

Ok then, one at a time

why are the wires in a plug covered in flexible plastic? - its insulation to stop the individual strands of wire touching each other and causing a short circuit.

why is brass used to make the pins in the plug? - 2 reasons, its a very good conductor of electricity and its very strong and resilient to being put in and taken out of the spring loaded metal strips that contact it in a plug.

why is the earth pin longer than the others? - its a safety thing, the earth pin goes in first and you cant insert anything into the other two holes until it has - its to stop kids frying themselves if they shove stuff into the holes.

why is thick cable used for some appliances and thin for others? - depends upon the amount of current it'll be carrying, a cable for an adaptor for a USB external drive say is thin because it uses a small amount of current, but your electric cooker uses tons, the wire has to be thicker to carry the amount of amperage travelling through it so that it doesn't overheat.

what is the purpose of a fuse? - its in case of a power surge, it will blow if too much current passes through it, the fuse blows and not your expensive electrical items.

Hope that gave you all you needed to know.

Answer 2

1. the wires are covered in flexable plastic are differant colours and the blue (negative) does a "U" turn to connect to the lefthand pin as you look down on the plug.
2. the earth wire (green and yellow) goes slightly left then forward to the big long pin and turns right to enter pin
3. the brown wire (positive) goes to the right and is the shortest wire
4. if you had to pull the cable out off the plug the first wire to disconect should be the brown as the wires would have no power
and the last wire to break is the earth
The pin are made of brass as brass is a very good conductor of electricty
the earth pin is the longest so in the case of a electical fault a short circuit would go to earth and blow the fuse and not you
each appliance uses 240 volts but not the same amount a light bulb uses 60 watts and only needs thin wire a electric heater 3000 watts five hundred time the power so needs a thicker cable
for every 1000 watts of power is 4 amps hence fuses are marked in amps
fuse are a protection for the appliance and should be set to the rate of the appliance
a electric kettle 2000 watts should have a fuse of 8 amps but the nearest is 10 amp fuse
do not try this at home.
but replace the fuse with a 40 amps fuse and something goes wrong the fault would go to your main fuse box and cause a lot of damage( by the way the biggest fuse you can get for a 13 amp plug is 13 amps

Answer 3

The wires are covered in flexible plastic so that they are insulated and the insulation is flexible so that it does not crack and compromise safety by having exposed live wires. Brass is used for the pins because it meets the criteria of having good conductivity, like copper, but, unlike copper, it is not soft and will not wear down with use. The earth pin is longer than the others because it is important to have the earth connected first for safety. This longer pin will come in contact with the circuit earth before the line or neutral will and this has been incorporated into the design so that, without the earth pin, little fingers cannot get to live equipment because the other two slots will not open. Thick cable is necessary when using electrical equipment with a heavy load, where there is less load, thinner wire can be used. The purpose of a fuse is to place a thin piece of wire in the circuit deliberately as a weak point so that, in the event of a short-circuit or surge of electricity, the thin fuse wire will be the first and only thing that blows, thereby protecting the concealed circuitry.
Many people use more higher rated fuses than are required. As an example, if you were cutting the grass with an electrical mower and you cut the lead by accident, in those conditions, damp underfoot, one-third of one amp is sufficient current to prevent you letting go of the appliance. Yet many fit a 13-amp fuse in them. To be safe you should always used a residual circuit breaker or an earth-leakage circuit breaker when using anything electrical that is not fixture or fitting. I hope this has enlightened you.

Answer 4

Wires are covered in flexible plastic to insulate them - To keep the electricity in as it were.
Brass is used because it is a good conductor and it doesn't corrode (Rust) and is easy to shape.
The earth pin is longer so that it's the last to disconnect and also the first to go into the socket to open the shutter to let the other two in.
Thicker cable has a lower resistance so it can carry more current.
As fuse is the weakest link in the circuit so that if a fault occurs then the fuse will break first and disconnect the electricity (hopefully) before anything else is damaged, including you.
As a matter of interest the size of the fuse is extremely important so don't just put in any old fuse. If the appliance is fitted with a 3A fuse DON'T be tempted to just stick a 13A fuse in.
Regards
Andy

Answer 5

the plastic is used for insulation against short circuit or earth leakage
not brass, but copper is used for conducting of the current flow and Copper is the most economic for mass production when compared to other conductors like gold, etc.
The earth pin should be the last to disconnect from the socket and thus ensuring maximum connection and protection by means of the Earth leakage protection device if there should be an accidental leakage or connection to the phases during removal of the plug
Thickness of the cable is limited to the current carrying capacity of the cable. Thicker = more current carrying capacity.(limited to the upstream protection circuit breaker.
A fuse will protect the downstream load on overload conditions. The filament inside is sized for the calculated load and will "blow" when exceeded and therefore protect the downstream load.

Answer 6

Wires are covered in flexible plastic so they can bend round corners.
They use brass pins because it makes a good contact
The earth pin is longer because it trips trap doors to let the other pins in
Different sizes of cable are used because some appliances require more current than others
The fuse is the safty mechanism that could save your life. it is a deliberate weak link in case of a short curcuit

Answer 7

Andy S is spot on, but if it's for an exam. The purpose of a fuse is to protect the cable/wire NOT the appliance!

Answer 8

noggi.... link just about covers it. The earth pin is longer because it pushes the plastic covers of the other two sockets on the wall outlet aside. The covers are there to keep small fingers from getting an electric shock.

Answer 9

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Answer 10

wires are covered for insulation,brass is used cos its cheap and conducts electricity well,the earth pin is longer because the earth socket is deeper,thick cable is used for higher rated voltages or for equipment that may be at risk of getting cable torn. a fuse is to stop the appliance being ruined by a fault,instead of losing your toaster you just lose a fuse.