You want to protect your tools and property.  You also want to make sure your tools run they way they should, at peak performance.  In order to protect your tools and make sure they run at peak performance, you should understand extension cords and their ratings.  Below is a table of the ratings of extension cords. 

  

Cord Length (ft.)	Gauge	Max Amps
25	18	10
25	16	13
25	14	15
50	18	5
50	16	10
50	14	15
75	18	5
75	16	10
75	14	15
100	16	5
100	12	15
125	16	5
125	12	15
150	16	5
150	12	13