This Shield uses relays to switch both AC and DC voltage at up to 10 amps. This is the advertised limit of the relays. You should leave some margin in their usage. Remember the current and voltage switched by the relays is different from the current and voltage turning on and off the relays. Turning on these relays consumes significantly more power than the other TAS versions. See More Than You Ever Wanted To Know About Arduino Uno Power and The Power Caboose in the TAS User Manual.