The electrical distribution system uses a three-level distribution box

Electricity is delivered at a frequency of either 50 or 60 Hz, depending on the region. It is delivered to domestic customers as. In some countries as in Europe a supply may be made available for larger properties. Seen with an, the domestic power supply in North America would look like a, oscillating between −170 volts and 170 volts, giving an effective voltage of 12. [pdf]