This has 2 core carrying the load and an earth. this is NOT 3 core
Cables are specified by the Cross Sectional Area (CSA) of their live & neutral conductors. This is measured in mm². Unfortunately a cable of, say, 10mm² is
often loosely referred to as 10mm cable, giving the false impression to people not familar with cable sizes that they just need to measure the width of the cable with a ruler. The table below gives some typical overall cable dimensions for some standard flat T+E cable sizes. Note that cables from different manufacturers will vary slightly from these dimensions.
Judging what cable size you have:
|CSA||Overall Dimensions||Diameter of each Live/||Number of strands||Approx Measurement across|
|Neutral copper core strand||bundle of strands (‘diameter’)|
|1mm²||7.8mm x 4.25mm||1.13mm||1 (solid core)|
|1.5mm²||8.2mm x 5mm||1.38mm||1 (solid core)|
|2.5mm²||10.3mm x 6mm||1.78mm||1 (solid core)|
|4mm²||11.9mm x 6.25mm||0.85mm||7||2.56mm|
|6mm²||13.5mm x 7mm||1.04mm||7||3.13mm|
|10mm²||17.1mm x 10mm||1.35mm||7||4.05mm|
|16mm²||19.4mm x 10mm||1.71mm||7||5.12mm|
This has 3 cores for carrying the load and an earth. mostly used in 2 way lighting circuits and interlinking smoke alarms.
3 core is also often used to power a fan, i.e permanent live, switched live and neutral.