The need for a sub-panel depends on several factors, including the electrical capacity of your existing main panel and the power requirements of the air conditioner and electric water heater.
If your main panel has sufficient capacity to accommodate the additional load of the air conditioner and electric water heater, you may not need a sub-panel. However, if your main panel is already near its capacity or does not have enough available circuit breaker slots, a sub-panel may be necessary to provide additional circuits for the new appliances.
Installing a sub-panel can help distribute the electrical load more evenly and prevent overloading the main panel. It can also provide convenience by allowing you to have separate circuits dedicated to the air conditioner and electric water heater.
It is recommended to consult with a qualified electrician who can assess your specific electrical setup, calculate the load requirements, and advise you on whether a sub-panel is necessary. They will be able to provide guidance on the appropriate electrical upgrades and ensure compliance with local electrical codes and regulations.