What would be the effect on an electrical panel if a tool were shorted across the busbars?

When a tool is shorted across the busbars in an electrical panel, this creates a direct low-resistance path for electrical current. The immediate effect of this situation is the flow of high fault current through the circuit. This occurs because the short circuit greatly reduces the impedance of the circuit, allowing a much higher level of current to flow than what the system is designed to handle. High fault currents can be several times greater than the normal operating current, leading to significant risks such as equipment damage, overheating, and even electrical fires if not addressed promptly.

In a properly designed electrical system, protective devices such as circuit breakers or fuses are in place to detect this excessive current and interrupt the circuit in order to prevent damage. This is why understanding short circuits and their consequences is vital for ensuring safety and correct function in electrical installations.