Page 659 - The City and Guilds Textbook: Plumbing Book 1 for the Level 3 Apprenticeship (9189), Level 2 Technical Certificate (8202) and Level 2 Diploma (6035)

Chapter 11 Electrical principles and processes for building services engineering

The layout of electrical supplies and

connections

Circuits
There are two types of electrical circuit:

● series
● parallel.

Domestic lighting circuits, ring final circuits and fused
connection units
The ring final circuit in domestic properties is run from the consumer unit, using
2
what is known as 2.5 mm flat profile thermoplastic cable. At the consumer
unit it is protected by a 32 A CB or 30 A fuse in the old system. It is known as a
ring final circuit because the cables from the consumer unit form a continuous
loop returning back to the unit. This means that for each ring final circuit, at
the consumer unit there will be two sets of line, neutral and circuit protective
conductors (earths). Sockets on this system will normally be used for televisions,
fridges, stereos, PCs and other household appliances.
You may also come across a radial circuit; this is a single cable from the
consumer unit and connects directly to each socket straight from the last one.
Radial circuits can also be run as separate circuits feeding just one load, such
as water heater, underfloor heating or a cooker. Figures 11.4 and 11.5 show
examples of a radial circuit and a typical ring final circuit.

p Figure 11.4 Radial circuit

p Figure 11.5 Ring final circuit
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