The 13 Amp PLUG

Fuse

InsulatingCasing

Live Wire

Neutral

Cable grip

FlexibleCopperconductors

Earth

FUSESIN

ACTION

fault

Extra current melts the 5 Amp fuse wire cutting off the live supply

Fuses are the weakest link in a circuit, preventing fires. They consist of a short, thin piece of wire with a low melting point.

EARTH &

FUSE

Appliances with metal cases need to be earthed.The earth pin is connected to the case via theyellow/green wire. If a fault occurs a large currentflows to earth and overloads the fuse.

L

N

The earth wire and fuse

L

N

---

-

-

-

--

-

Fault-Loose wire

The earth wire and fuse

L

N

---

-

-

-

--

-

Fault-Loose wire

The earth wire and fuse

L

N

E

The earth pin is connected to the metal case via the yellow /green earth wire

If a fault develops a larger current can flow down the earth wireand melt the fuse wire cutting off the supply on the LIVE wire

The earth wire and fuse

321

Errors in Wiring Plugs

321

Errors in Wiring Plugs

321

Errors in Wiring Plugs

321

1. Bare wires showing2. Proper fuse not installed3. Earth wire not connected

Errors in Wiring Plugs

321

4 5

Errors in Wiring Plugs

1. Bare wires showing2. Proper fuse not installed3. Earth wire not connected

321

4 51. Bare wires showing

2. Proper fuse not installed3. Earth wire not connected4. Live and neutral swapped

Errors in Wiring Plugs

Errors in Wiring Plugs

321

4 51. Bare wires showing

2. Proper fuse not installed3. Earth wire not connected4. Live and neutral swapped

5. Loose cable grip

Why are sockets wired in parallel with each other ?

The longest pin of a plug is designed to make contact

with the earth wire

A ring main circuit

FUSES, EARTH WIRE AND PLUGS

ShockCurrent( mA)

Effect

> 25 DEATH

10 - 25 PAIN Can’t let go

0-10 TINGLE

Wet hands have a much lower resistance.

If your body has a resistanceof 100 and you touch alive wire at 230V, whathappens?

Safety with mains electricity

* Replace broken plugs and frayed cables* Keep plugs & cables away from water or heat* Never overload a plug or socket* Don’t use wet hands when switching on or off

Appliances with plastic cases do not need an earth wireWhy not?

The insulating plastic prevents users getting into contact with ‘Live’ components

Circuit breakers work quicker than fuses.( saves lives)

CIRCUIT BREAKER

They are easily reset by pressing a button

CIRCUIT BREAKER

neutral

liveparallel

earth

series

melts

Brass – stiff, good conductor

Copper – malleable, good conductor

rubber – flexible, good insulator

Stiff plastic – tough, rigid, good insulator

1a. A Fuse cuts off the supply if there is excessive current caused by a fault.

1a. A fuse is on the live side so that the appliance remains safe from the live voltage.

1a Circuit breakers work quicker than fuses.( saves lives)

yes

The off switch should prevent the live voltage reaching the element

New switch location

mel

ts