My knowledge of US electrical systems comes from cable DIY shows (which for someone familiar with UK electrical practice is scary viewing), but I believe that each circuit is typically 20amps. I think an average house has about four or five circuits, so what you have hooked up doesn't sound too much.

In the UK, each socket is rated to a maximum of 13amps, with a total of about 30amps for the circuit and each plug has a 3-13amp fuse.