[header] How to fish wires through a conduit or pipe [title] Unwind several feet of the light string and feed a little bit of it into one end of the pipe. [title] Start up the vacuum cleaner and attach it to the other end of the pipe. [step] Try to seal the connection the best you can to make the most efficient use of the vacuum. 
The vacuum should pull the string through the pipe.. [substeps] Watch the end where the string is feeding into the pipe to make sure it doesn't get snagged and stop.