Daniel,
Just to clear up any confusion, I believe Pat is referring to a GFCI (Ground Fault Circuit Interrupter). They are outlets typically found around water areas like kitchens and baths.
Pat has some great advise here. Something every reefer must have is a GFCI outlet to protect humans, fish, corals, and all those other critters. You can literally loose an entire tank or worse without them. I've seen two posts, just this year, on ARC where people have come home to almost everything being dead. Make sure to read the directions carefully before installing. Follow them exactly and you should have no problems. They are cheap, about $10 at Walmart, Home Depot, Lowes... and take about 10 min to install.
John