All of us home DIY compressor users have to plug our portable compressors in somewhere. And often, that somewhere is farther away than the electrical power cord that comes with our compressors can reach.
The compressor power cord is the length it is because that’s the recommended length of a power supply to that unit, based on the electric motor size and power demands of that unit.
If you add an extension cord to lengthen the reach from the compressor to the outlet, you can actually damage the compressor motor, as electricity, along with compressed air and other fluids, suffers “pressure drop” as the lines get longer.
In terms of the electric motor, if the extension cord is too long, not enough power gets to the motor and it’s operation suffers. That suffering is often manifested in higher heat generation. This isn’t good.
That’s why the rule of thumb for portable compressors is….”add a longer air hose, not a longer extension cord” when you have to reach a distant workpiece.
Yes, the longer air hose will create pressure and flow drop in the lines to the air tool, but the nature of the air tool is that it will not be damaged by a drop in supply pressure. The worst case scenario is that there won’t be enough air to the tool to do the job, but the air tool itself won’t be damaged.