0kelseymh 10 years ago ReplyUpvoteIf the circuit itself can support 20 amps of current, you should install plugs which can handle at least that same current. Otherwise you'll eventually forget what you did, and plug a 20 amp load into the 15 amp plug, and get more warmth in the wall than you might like.As for how many amps a given load pulls, the formula is easy (and even applies to AC): watts = volts × amps. Your wall puts out 120 volts. Look on your curling iron or hair dryer for it's wattage, and just divide: amps = watts/120. A 1500W hair dryer uses 12.5A. A 100W light bulb uses 0.83A. and so on.