Current Carrying Capacity for SWA Cable
In this section we will go through all the technical specifications used when sizing an armoured cable for an installation ahead. We will cover the maths behind volt drop calculations. Then You will find links to pages that will go more into the specifics of that cable, i.e. 2 core and 3 core etc. We hope this will keep the page a little less crammed with numbers and allow you to find what you are looking for quicker.
Information on the following pages will include.
- Nominal Cross Sectional Area (mm2)
- Approx. Overall Diameter (mm)
- Approx. Diameter Under Armour (mm)
- Nominal Diameter of Armour Wires (mm)
- Approx. Cable Weight (kg/km)
- Maximum Conductor Resistance @ 20 Degrees C
- Conductor Short Circuit Rating (1 Sec/kA)
- Three Phase AC Clipped Direct (Amps)
- Three Phase AC Free Air (Amps)
- Volt Drop Three Phase AC (mV/A/m)
The Maths behind SWA cable volt drop
The following formula is used to calculate Voltage Drop = (mV/A/m) x Ib x L / 1000.
- (mV/A/m): To find the value for (mV/A/m) we need to look in the current carry capacity and voltage drop tables on the pages below.
- Ib: This is in AMPs, design current which is watts divided by voltage.
- L: length of the circuit in metres.
We divide it all by 1000 to convert the figure from Millivolts into Volts
You should have no less than 3% volt drop for a lighting circuit and no more that 5% for any other circuit, if you do you need to up the size cable and re-calculate until you are within the permissible volt drop %.
Current Carrying Capacity for SWA Cable 2 Core
Click this helpful link to take you to a table containing the technical specifications and Current Carrying Capacity for SWA Cable 2 Core.
2 Core armoured cable is generally used where an earth cable is not needed or the armouring is being relied on as the earth.
Current Carrying Capacity for SWA Cable 3 Core
Follow this link to the very popular 3 core armoured cable pages, this time containing the technical specifications and Current Carrying Capacity for SWA Cable 3 Core.
3 Core armoured cable is one of our most popular cables, perfect for 220-240v single phase installations. Garage supplies, garden lighting etc
Current Carrying Capacity for SWA Cable 4 Core
Follow this link to a table of technical specifications and Current Carrying Capacity for SWA Cable 4 Core.
4 core armoured SWA cable is a very well used in the industry when a 3 phase and earth is needed also known an TP+E, many industrial machines needed this ranging from welders to milling machines. If used as a three phase and neutral and earth power cable, you would need to use a extra earth cable.
Current Carrying Capacity for SWA Cable 5 Core
The following link below contains a Table of technical specifications and Current Carrying Capacities for SWA Cable 5 Core.
5 Core Armoured SWA cable is often used for three phase and neutral and earth circuits or sometimes know as TP+N+E. This saves the need for pulling an extra earth cable in but can work out a little more expensive, the labour saving normally counters this however.