remember Razz, the longer the extension cord the more electricity you will be sucking. if your cable is a standard 1250w orange extension cord which has a gage rating at around 16 you will only be able to run one light and one fan or so. if you got a wire from a different location i.e. your power box that had a gage rating of 8 you could probably run your whole setup off of one cord.
it also depends on the length of the distantce or cord. a 16 gage cord under 50 ft will give you ruffly 1650w where a 16 gage cord over 50ft will only give you 1250w. if your stoned like i am you might have to read this twice. hope any info helps.