ECN Forum Forums Code Related Discussion NEC & other Code issues When is a system considered overloaded?

Glenn:

The smallest OCPD generally used in domestic panels is 5A for lighting circuits, the next fuse size being 15A, but C/Bs are also available in 10A. Many new ranges of breakers are actually 6A instead of 5A due to the adoption of European stadards.

Twin-&-earth (like Romex) 1 sq. mm can be run the same way as the larger sizes, with no special requirements.