Dixon, are your refering to a surge suppressor ? Surge suppressors are for a massive spike in current , so say your house gets hit by lightining it will trip and protect your equipment from a overvoltage spike that fries it all. A gfi is a device that protects the end user from becoming the ground and getting electrocuted , like say haveing a hair dryer dropped into water it immediately trips the gfi. But if you run anything that is higher amps than the gfi is rated for it will also trip the gfi. So if u put lets say 16 amps on a 15 amp gfi it will trip. but if you have a 20 amp gfi it shouldn't . But there is also a cliff not to a 15amp and 20 amp NEC ( National Elec Code ) says you cannot exceed 80% of what the circuit is rated for ,Ie 20 is only rated at 16 amps and 15 amps is only rated at 12 amps . That is why most lower amp gfi will always trip but if you use and split the load it usually solves the problem . On a note of caution if you put a 20 amp gfi on a 15 ampo curcuit you run the risk of burning the insulation off of the wire before it trips which can cause a fire . # 12 awg wire is 20 amp and 14 awg wire is 15 amp ratings . Sorry for the long winded explanation but better safe than sorry .