John wrote:
My dryer needs 220V 16A. My wall sockets carry 220V 10A. There is a 400V 16A box
also in the room. After opening the box I noticed only three wires: red, blue and
black. Voltmeter shows they do carry 400V. How do I get 220V from this
connection?

Usually there are five wires in other 400V 16A boxes in the house: two sets of
blue and red and one black for ground. To get 220V I just use one blue and red +
ground.

The breaker box has three 16A breakers for this 400V 16A box (I presume). What if
I switch two breakers off? Would the 400V 16A have 220V 16A instead.

What country is this in?