I just confirmed by going out to the garage and checking what I had on hand that the Red Dot switch is only 15 A, not 20 A. I could swear I used one that was 20 A, but it may be a different brand, because checking HD's website all I could come up with for Red Dot was the 15 A... So, why would 15 A not be adequate for just a handful of fixtures on say a small overhead arbor? For instance, four 20 W fixtures would be 80 W. 80 W/ 12 V = 6.67 A, right? Three fixtures x 20 W would be 5 A. Five fixtures x 20 W would be 8.34 A. Or am I doing the math wrong?