9 10mm
cable satisfies the current and drop voltage requirements when the circuit protected by
an MCB.5 30
13A socket outlets (Ring circuit) 2.5 100 90
13A socket outlets (Ring circuit) 4.5 30
13A socket outlets (Radial circuit) 2.Basic Electrical Installation Work
302
Now test for volt drop: from the table shown Table 14. These are some the decisions which the electrical contractor must make when
designing installation which meets the requirements the customer and the IEE
Regulations. 3.5 30
Cooker (oven only) 2.5 60
Immersion heater 2. were able route the cable under the floor, clipped direct conduit or
trunking wall, may able use 6mm cable for this load.0 40
Shower (up 7.0 35
Cooker (oven and hob) 6.
In this table, assuming standard 230V domestic installation, hav-
ing sheathed earth PME supply terminated 100A HBC fuse the
mains position.0 40
Shower (up 9. You can see how the
current carrying capacity cable varies with the installed method looking Table 4.0 40
Fixed lighting 1. the volt drop for this cable length and load equal to:
4 06
3
.4 gives guide cable size.
Cable size for standard domestic circuits
Appendix the IEE Regulations (BS: 7671) and Appendix the IEE On
Site Guide contain tables for determining the current carrying capacities of
conductors which looked the last section.5kw) 6.
Compare the values column with those column When the cable clipped
direct wall surface the current rating higher because the cable cooler.6kw) 40
Key Facts
Volt drop
Maximum permissible volt drop on
230V supplies:
● for lighting 6. However, for standard
domestic circuits, Table 14. This cable run loft that gets hot summer and has thermal insulation
touching one side the cable.4mV.3 the volt drop per ampere per metre
for 10mm cable 4.4 Appendix the IEE Regulations.2. Final circuits are fed from consumer unit, having Type B,
MCB protection and wired PVC insulated and sheathed cables with cop-
per conductors having grey thermoplastic PVC outer sheath white
. V/Am V
Since this less than the maximum permissible value for lighting circuit 6.5V
IEE Regulation 525 and Appendix 12. the
alternative route was longer, you would need test for volt drop before choosing the
cable.
If you are unsure the standard fuse and MCB rating protective devices, you can refer to
Fig. must, therefore, use installed reference method of
Table 4.2.9V
● for other uses 11.5 30
Storage radiator 2.
Table 14.4 Cable Size for Standard Domestic Circuits
Type final circuit Cable size
(twin and
earth)
MCB
rating,
Type (A)
Maximum floor
area covered
by circuit (m2
)
Maximum
length of
cable run (m)
Fixed lighting 1
