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Current electricity

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Figure 2.49: The tree system method of house wiring

In the distribution box, there In the loop-in lighting circuit, the live, neutral, and
are lighting fuses and power earth wires run from the consumer unit to each of
fuses. For example, there are the ceiling designs, one after the other. From each
separate fuses for lighting in rose, another set of wires runs to the switch, which
corridors, bedrooms, the living operates the light. Figure 2.50 illustrates the loop-
room and the kitchen. Most in circuit.
houses have light fuses rated 5
A and fuses for power sockets From previous
usually rated 15 A. Hence, ceilling rose To the next
ceilling rose
cables for power points are
different from those for lights.
Lighting circuits control the
lighting fixtures in a house. Ceilling rose
Unlike the ring circuit, the Wall
lighting circuit does not form a switch
loop returning to the consumer To light fitting
unit. Instead, the consumer
unit is normally connected to Figure 2.50: Loop-in circuit
the first lamp, which in turn is In the junction box lighting circuit, neutral and
connected to the second lamp, earth wires run to one junction box after another.
and so on. There are two types From the junction box, one wire runs to the light
of lighting circuits: loop-in and the other runs to the switch for that light.
lighting circuits and junction Figure 2.51 illustrates the junction box lighting
box lighting circuits. circuit.

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Physics Form 2 Final.indd 77 25/10/2025 10:26