[marcosdumay]

AFAIk, the rationale for extension chords is that they are sized to cause a controlled amount of voltage drop within their lenght. If you keep adding them, you will increase the drop, and many devices will react by increasing the current.

[quickthrowman]

This is correct. For a 120v 12FLA load at a distance of 50’, you’re fine using a #14 cord. If you double that to 100’, you need to use #10 cord to account for the voltage drop. As voltage drop increases, the amount of current flowing through the cord increases, which can potentially heat up the insulation beyond its rated temperature.