I have a friend who wants to hold a rave in a cave, quite literally in a cave so he wants electricity and a sound system, I said he'll need some kind of portable generator but I dunno how this would wire up to a PA as they have those funny circular 3 pin things, does anyone know about this sort of thing, there will be quite a lot of people going so it needs to have a fairly high wattage I presume.
thanks
Collisster
Nothings impossible.
What size audience are we talking here? for a few hundred, you'l need between 1kw-10kw for sound, and the same for lighting, more if it will be at night. Once you get past the 1000 figure, you'll need to fly the tops, and use many subs otherwise the people at the back won't hear a thing. If you get 100 people at say £10 a ticket you should be able to cover your costs...
You'll need to hire a sound engineer (at least) which will be £20 per hour minimum. You could hire the gear (amps, speakers, decks, lights) for around £500 for a day, but the more lights, amps and speakers you have the more it will cost. I'd hire an electrician, but some sound engineers are qualified electricians, so you may be able to get 1 guy to run your entire system if he knows his stuff.
As far as generators go I have no idea of the cost. I've have seen people use deep cycle car batteries for very small PA systems tho, so this is another option.
Generators use 16A, 32A and 63A waterproof plugs, but you can get convertors that go from 16A to a normal 13A plug.
You may also need public liability insurance also, but I'm not a promoter (so I don't know about this side of things), I just hire out the gear, set it up, and DJ also if needed.
As for the echo (reverb really), just glue or attach some cloth to the walls, or pack it out with people.
EDIT: Just seen you mentioned audience size = around 100 people. This is really no problem... have the geni outside the cave, use long mains cables. You won't need a huge PA rig for 100 people. Just tell the sound hire company what you are doing and they'll suggest a system, it will be somewhere between 1kw-5kw (power isn't everything tho).