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replaced, faulty brakes, used, faulty electrical connections,
tightened, frayed cables, recharged, damaged tools, touched with
wet hands.
a flat battery, must not be checked, regularly,
a loose nut, never, measured accurately,
a broken fuse, repaired,
a defective machine, adjusted,
a broken light bulb, made, voltage, worn, correct clothing,
a faulty switch, worn tyros.

Ask and answer questions about the table above.

Look at the examples: Why were the cables replaced? Because
they were faulty.

Step 3

PROTECTIVE DEVICES

The cables that carry electric current to the different
appliances in the factory are called conductors. Their resistance to
the flow of electric current causes heat to be generated. If the flow
of electricity in a circuit suddenly increases, the heat in the
conducting wires increases and can cause the insulation to burn,
resulting in damage to the equipment and possibly causing a fire.
All electric circuits must therefore be protected by manual trip
switches, fuses or automatic trip switches, which cut the supply
where there is a fault.

Manual Trip Switches
Manual trip switches can be inserted in the circuit and are
used to isolate equipment from the supply if a fault occurs.

Fuses
Every circuit should have a fuse in the supply line to the
equipment. The fuse can be of the cartridge type which is held in
place by two spring clips or can be a piece of wire joining two

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