We use a tester, that we can plug into a meter socket that applies 25amps of load to a phase and neutral. The unit uses a toggle switch to allow us to test both phases one at a time. The unit is basically has two hair dryers in it and two panel voltmers meters to indicate the affect of applying the load & pick up points to allow you to use a handheld voltmeter to check the voltage. The units we use are made by Arnett Industries: http://www.arnettindustries.com/products/supbeast/supbeast.htm
I think the above unit is great for utility work, where we test at the meter socket, but for checking outlets, why not use a 1200 watt hair dryer. You could plug it in to the outlet in question, or make an adaptor with insulated alligator clips for checking breakers or connections.
[This message has been edited by ameterguy (edited 01-18-2003).]