I'm no expert but don't the breakers ensure that no wire carries more than 20 amps?
Depends on the switch rating.
Most are 15 - 20 amps.
When a power surge occurs , the excess electrical energy gets converted to heat due to "electrical friction"*.
*The amount of electricity exceeds the capacity to flow safely on that circuit.
The heat causes the spring in the circuit breaker to expand and "pop"
This opens the breaker switch and stops the flow of electricity on that circuit.
remember , volts x current = watts of electrical power on the line.
Typical USA power line is 120 Volts AC x 20 amps of current = 2400 watts max per line