The answer to 'why is my switch circuit overload' is that a switch circuit can become overloaded due to several common causes, such as too many devices connected, a short circuit, or a problem with the wiring. Symptoms of an overloaded switch circuit include flickering lights, buzzing noises, and tripped circuit breakers. To resolve the issue, you'll need to identify and address the root cause, which may require shutting off power, inspecting connections, and potentially upgrading the electrical system.
If you're not comfortable working with electrical systems, it's best to call a licensed electrician to diagnose and fix the problem safely. Attempting DIY electrical work without proper training and experience can be extremely dangerous and may even lead to further damage or personal injury.