# What is the correct way (read “correct way according to the law”) to choose the section of a power cable in the EU and UK?

I am wondering if there is a standard process across the EU in particular Germany, France and the UK, for choosing the the section of a power cable.

Suppose that:

• the cable is to be installed in an industrial/civil low voltage application (400V three phase or 230V mono phase, your choice, if it makes any difference, please explain why).
• The power factor is given
• The cable is isolated with PVC.
• The cable is protected with a fuse or an automatic switch.
• There are no other special requirements.
• The user is using the line at full power all the time (think of an industrial motor running 24/7 for instance).

How would you need to choose the section of the cable, the size of the fuse/automatic switch in such countries according to the law? Is there a common framework?

If you need a specific case to study, please refer to a common home appliance that should be able to provide, at worst, 4kW continuosly.

• In the UK, you'd be looking for the appropriate section of BS7671. – Jack B Mar 17 '17 at 0:06
• With a given fuse rating, the size of the conductor is trivial. Else you need a table: given nominal current, distance, ...I have a cardboard slider from ABB somewhere, where you slide those parameters and get the result. – Marko Buršič Mar 17 '17 at 0:21
• For home appliances there is a simple table (current per wire): 10A - 1.5mmˇ2; 16A - 2.5mm^2 ; 20-25A - 4mm^2 ; 35A - 6mm^2. In EU, for home appliance you need wires line-black, neutral-blue, PE-green/yellow: 1.5mm^2 - lights, 2.5mm^2 - sockets, 4mm^2 - cooking top. – Marko Buršič Mar 17 '17 at 0:35
• You can use pretty much any size of cable, as long as the upstream fuse or breaker protects it. So, choose a current capacity of fuse sufficient for your load, then choose a cable size rating big enough to be protected by that fuse. BS7671 has got the ratings. – Neil_UK Mar 17 '17 at 7:05