Hello Roland, and welcome to ECN. That's some nice neat work! [Linked Image]


Just to expand upon classicsat's comment, the U.S. system most common for the average individual house is a 3-wire 1-phase system. The transformer has a 240V winding with a center tap which is grounded and brought to the house as a neutral.

There are then two line busbars in the distribution panel. Circuits for lights and regular wall outlets are then wired between one line and neutral to give 120V, the load being distributed evenly between the two sides.

Large appliances such as dryers, stoves, heating, and air-conditioners run on 240V and are connected via 2-pole breakers to both live sides of the supply.

Grounding (earthing) is indeed what would be classed as TN-C-S in Europe. TT systems are not used in the U.S., and in fact are prohibited under the American NEC (National Electrical Code).

There are a good many significant differences between grounding and bonding arrangements in North America and Europe.