If the entrance line of the old house is open wire or pipe, it is ok to use the 32A master gate indoors. If it is buried underground, it is best to use 25A. Your electrician's talk about using C60 as the main brake is pure nonsense, and it is even more nonsense to directly branch from the main brake to the socket. It is reasonable to set these new special switches for high-power machines after the main brake, that is, divide them into three power circuits.

In terms of power supply circuit, in addition to the original two circuits, there are three circuits behind the main switch in the distribution box at home, 10A circuit breaker and 1 for 1P air conditioner. 5 square lines, 16A circuit breaker, used for 2P air conditioner and 2 sets. Line 5, if the electric water heater is a general water storage machine, you can use 10A circuit breaker and 1. 5 square lines (if there is a high-power machine above 2,000 W, use 16A circuit breaker and 2. 5 square lines).

Why do these appliances need a single circuit? Because the power of these appliances is relatively high, if they are combined into one or two circuits, they will affect each other when starting.

Why don't you use a 4-square line like you said? It is certainly good to use 4-square wires, but because the newly added wires are open wires with good heat dissipation conditions, the safe current carrying capacity of the same wires is higher when exposed than when buried through pipelines, so it is of little significance to use 4-square wires. Of course, if your two air conditioners must be combined into one circuit, then the air conditioner circuit will use four square wires and 25A circuit breakers.