Tracing an electrical circuit can be a complicated task that can be accomplished in many ways. The easiest way of tracing your electrical circuit is to get a building plan for the house. Many times the local building department keeps a copy and will show you all the electrical circuits. The most common technique, when there are no blueprints available, is to use a stud-finder with a wire-sensing mode.
Things You'll Need
Find the circuit breaker that feeds power to the outlet. Connect the lamp to the outlet and turn it on. Go to the electrical panel and turn off one of the breakers. Check to see if the lamp turned off, keep doing this until you find the right circuit breaker.
Turn off all the circuit breakers in the house except the circuit breaker to the outlet you are trying to find the circuit too. This is the circuit breaker that turned off the lamp; its the only one that will remain on.
Scan, with your stud-finder, the wall around the outlet until the wire sensor light turns on. Keep moving along the wall following the sensor light; this will be the route the cable was installed through, also known as the complete electrical circuit. Make sure the stud-finder has a wire-sensing mode it will say it on the packing and usually has a lightening bolt picture on it.