Twin and Earth & Flat Cable Technical Specifications
In this post we will talk over all the technical specifications of twin and earth cables, from current carrying capacity through to bend radius and the temperature, environments the cable is designed to be installed in.
- 1.5mm twin and earth a very common cable to use in house hold lighting
- 2.5mm twin and earth the vast majority of 32A ring main circuits use this cable
- 4mm twin and earth used in radial circuits and smaller cookers and electrical hobs
The table below shows some of the information needed when deciding what cable is needed for a specific job. Firstly the cable size in CSA this is how electrical cable is measured. In the second and third column we have the Reference method this is how the cable will be fixed to the wall or pulled through a conduit in buried in a wall. You should notice there is a vast difference in the current carrying capacity of the cable depending on which method is used. Lastly we have volt drop the unit for this is MV/A/M, This is used in the below Equation to work volt Drop.
| NOMINAL CROSS SECTIONAL AREA mm2 |
REFERENCE METHOD A* (IN CONDUIT IN WALL) Amps | REFERENCE METHOD C* (CLIPPED DIRECT) Amps | VOLTAGE DROP mV/A/m |
| 1mm | 11.5 Amps | 16 Amps | 44 |
| 1.5mm | 14.5 Amps | 20 Amps | 29 |
| 2.5mm | 20 Amps | 27 Amps | 18 |
| 4mm | 26 Amps | 37 Amps | 11 |
| 6mm | 32 Amps | 47 Amps | 7.3 |
| 10mm | 44 Amps | 64 Amps | 4.4 |
| 16mm | 57 Amps | 85 Amps | 2.8 |
Cable Volt Drop Calculation for Twin and Earth Cable
Vd = mV/A/m x I x Ib ÷ 1000
- mV/A/m = the voltage drop per metre per amp
- I = the length of the circuit conductor in metres
- Ib = the design current
The permissible voltage drop for low voltage 240V installations is 3% for lighting and 5% for other uses.
Further information and technical specifications for twin and earth cable
We have a dedicated page for each size of twin and earth cable please click the link to the size you need.
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