There are rules of thumb but it depends on the load, the application and the installation method. So, for instance, a cable carrying a relatively high current needs to be much bigger if the cable runs through roof insulation material, than a cable installed in free air.
If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.
Select the supplier or trade you require, enter your location to begin your search.
Are you a trade or supplier? You can create your listing free at DIYnot Local
