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Most home haunts use props will need 120VAC to either run the props itself or to use lights to make the props visible. The advantage of the 120VAC is it is usually available via a outside socket and you can put a outdoor timer (this is a nice $11 unit with easy settings) on it so your props,lights, sounds turn on and off automatically. If you're like me, you'll want to have your stuff turn on outside at sunset and have them turn off before Midnight. I'd suggest you get a simple timer and not the kind with photocells on them. They act goofy when your prop lights hit them. Better to get the simple trusted timer with little pegs on them to set when you want the power to go on and off.
You'll need plenty of extension cords and try to only use the ones for outdoor use that have a ground prong on them. I also use a bunch of 3 way taps on the end of the cord coming from the timer to power various stuff. All of my outdoor outlets are GFCI, so are safe. Yours should be too. I typically run one big 120VAC 15 Amp rated outdoor extension cord from the timer to a bunch of 3 way cube taps all plugged in together. You just have to watch your wattage load on this set and don't go over. Usually, with a few lights, props, gadgets...you'll be fine.
You can use Halloween props that run on batteries (9V, 1.5V, etc etc) but you'll have to keep going out and switching them on and off. One way to take care of that is to use battery eliminators to have the outdoor timer turn them on and off.
Check out this diagram of the way I set up my power to my props. Many home haunters use a similar setup.