If you have cord damage. This will cause over-heating, an overall loss of power. If the cord is damaged, it acts like a minor/major kink in a clog in a water pipe and the cord can not deliver adequate electrical flow to the tool's motor. This means the tool will have to work significantly harder to perform which will, in turn, cause the motor to heat-up which will eventually cause damage to the tool's interior components. Always use the shortest length extension cord possible.