Flexible cords - choosing the flex

Cable Flexes

Flex or cable?

There are two types of electric wiring: flexible cords (flexes) (1) connect electrical appliances to the mains via plugs; cables (2) are used for permanent wiring around the house.

Flex in hand

There are many sizes and types of flexible cord. They are all made up of two or three separately insulated cores. In each of these cores the conductor is made up of many thin strands of copper which give the cord its flexibility.

In three-core flex the cores are colour coded: brown for live, blue for neutral, green and yellow striped for earth (3).

Two-core flex has only the live and neutral conductors, coloured brown and blue. The outer sheath of a flex can be PVC or rubber or rubber/textile braided. Two-core flex can have a round or flat sheath.

Note: If you are replacing a cord on an old appliance you may find that the colours are different from those now available in shops. The old green is now striped green and yellow to be connected to earth or E, the old red is now brown to be connected to live or L, and the old black is now blue to be connected to neutral or N.

Choosing the flex

Size of conductor

To select the correct size of flex you must know the wattage of the appliance. This can be obtained from the rating plate on the appliance (4). Some appliances such as freezers, refrigerators and vacuum cleaners need a size larger than the wattage indicates. Select the size from Table 1 below.

Table 1

Wattage up to (Amps) Conductor size Typical appliances
720 (3A) 0.5mm2 Table lamps, food mixers, certain hair dryers. Note: length must not exceed 2m
1440 (6A) 0.75mm2 Refrigerators, vacuum cleaners, electric drills, irons, high power hair dryers, televisions
2400 (10A) 1.0mm2 New kettles, 2kW fan heaters
3240 (13.5A) 1.25mm2 3kW fires, older kettles
3840 (16A) 1.5mm2 Storage heaters, immersion heaters

Number of cores

Three-core flex is used on appliances needing an earth, (usually metal cased appliances). Two-core flex is used for double insulated appliances. Look for the double insulated symbol (5).

Type of insulation

There are several types of flexible cord. The more common ones are listed in Table 2.

Table 2

Type of flex Typical appliances
Parallel twin PVC Clocks
Light duty PVC Fridges, televisions, sewing machines, food mixers, domestic hair dryers, table lamps, plate warmers. All appliances not too hot to handle
Ordinary PVC Washing machines, tumble dryers, vacuum cleaners, lawnmowers, toasters
Rubber with oil resistant sheath Frypans - hot appliances
Rubber textile braid or ordinary duty PVC Room heaters
Rubber/textile braided Irons
85°C rubber high temperature cords Immersion heaters, storage heaters
Light duty 85°C PVC cords Pendant light fittings

When you have decided on size, number of cores and type, then you can select the correct flexible cord for your particular appliance.

Table 3 below is a ready reference guide showing which flexible cords can be used for certain typical appliances.

Table 3

Appliance Typical wattage Flex size mm2 Number of cores Flex type
Iron 1200 0.75 3 Rubber/textile braided (unkinkable)
Toaster 1400 0.75 3 Ordinary duty PVC
Room heater 1400
Rubber insulated textile braided or ordinary duty PVC
Vacuum cleaner 400 to 1000 0.75 2 or 3† Ordinary duty PVC
Lawnmower 700 to 1400 0.75 2 or 3† Ordinary duty PVC
Kettle 1200
Ordinary duty PVC. Recommended buy complete with connector
Extension lead 1000
Ordinary duty PVC *when fully uncoiled
Immersion heater
Storage heater
3000 1.5 3 85°C rubber insulated high temperature cord
Clock 1 0.5 Usually 2 Parallel twin PVC, length not to exceed 2m
Slow cooker 1500 1.0 2 or 3… Ordinary duty PVC
Deep fryer 1500 1.0 2 or 3… Rubber with oil resistant sheath
Hair dryer
Food mixer
1400 0.75 2 or 3… Light duty PVC
Table lamp 40 to 100 0.5 2 or 3… Light duty PVC. Length not to exceed 2m, if it does exceed 2m, use 0.75mm2 flex

† Where 2 or 3 cores are shown above replace as the maker intended.

Produced in association with Northern Ireland Electricity.

Produced in association with Northern Ireland Electricity - www.nie.co.uk


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