We're doing an outdoor movie next week for a local business who expects around 300 people.

I have an inflatable screen...200 lumens projector...DVD player...and 1500 watts of powered speakers

so...I need to know if I should look at any special elecvti4racl or power needs?

You guys who do this stuff for a living...what do you do for power?

are there formulas to figure out this stuff..because someone mentioned a power drop if I use over 200 feet of extension cord plus al of my components

Better get a brighter projector! I hope you mean 2000 lumens?

1500 watts of speaker- but what is the receiver?

I'm no electrician, but to say that power is degraded over 200 feet might be a myth.

Add up all the max watts of each component. If it's greater than 1440 Watts, a 15 amp circuit won't do - or will do just barely. Probably best to go w/ 20 amp circuit. The formula is 80% of (volts x amps) = watts not to exceed. So 120 volts x 15 amps (normal house circuit) = 1800 * .80 = 1440 max watts to be safe.

I don't exceed this when I show a movie in the backyard, so a normal 15 amp house circuit does me just fine.

4 speakers,,,,(all self powered)

2 500 watts...

2 200 watts

14000 watts total

Like the poster above, I hope that's a 2000 lumen projector and not 200...YIKES!! For 200 Lumens you'll need to be inside a cave with absolutely no other light sources.

14,000 :eek: - I think your math is off.... 2x500 = 1000, and 2x200 = 400, that's 1,400 not 14,000. :)

My guess would be 2 circuits for the speakers (1x500 and 1x200 speaker on each circuit), just to be safe. and a 3rd circuit for the projector.

14,000 Watts! Better get a stadium concert production crew in there to help you !!!

You didn't add the watts for the receiver, the PJ, the DVD player, the popcorn machine, etc....

Once you get those, grab a calculator and see what comes out.

My guess is it will be less the 3000 watts. Better get 2 15 amp circuits.

oops...
1400 watts of self powered speakers

Do you mean to say that you'll be running a 200 foot extension cord or cords to where you'll be showing the movie? If this is the case, there will definitely be a significant voltage drop, probably on the order of at least 10%.

If you want to do this, make sure you get the absolutely thickest cord you can find, probably 12ga. It won't be cheap.

If on the other hand, you're just using a total of 200 feet of cord and you're only 50 feet or so away from the outlet, you should be OK. Of course, if this is the case, you should simply run one cord to a surge protector strip and plug into that.

Jim

The biggest power draw in our backyard theater is the popcorn machine (!), probably about 800 watts when the popper is going, more like 200 with the warming element and lamp only. But it gets its own 15A circuit anyway.

The 2nd biggest draw is the projector, probably 250 watts. Everything else (5.1 receiver, powered sub, DVD player, low voltage lights etc.) probably averages well under 200 watts, so all this works fine on a single 15A circuit, and reduces the risk of ground loop hum too. The really loud scenes with heavy low frequency effects may drive that up a lot, but it only lasts a few seconds and we have never tripped the single 15A breaker on any loud and LFE-heavy material.

Speaker power figures usually refer to their maximum peak power handling capability before excessive distortion from cones bottoming out, at least for passive types. Self powered types still probably refer to peak capacity before clipping in the internal power amp. In any case I'll bet the "1400 watt" set of self-powered speakers with motion-picture type audio probably averages just a couple of watts draw per speaker. On the other hand a heavy-metal rock music DVD might push that up to 10-20 watts, still totaling a fraction of 1400. 10 watts average continuous audio into a reasonably efficient speaker is louder than most people can stand at typical distances.

You'll probably want to do a "dry run" test with the equipment, but it sounds like a single 15 or 20A circuit (with suitable heavy guage extension cords as already pointed out) should work fine.

WELL!!...we made it...the blower was powered by the generator

the self powered speakers, PJ, DVD player, mixer, were powered by household ciruit..200 feet away...

Thank you all!...(BTW not sure how to tell how mush amperge these speakers required...I thought 500 watt speakers drew 500 watts..can you explain?)

500 Watts would've been the max the amp in them output.

500 Watts would've been the max the amp in them output.
There are some peculiar "Madison Avenue" aspects to power ratings for power amps (and speakers too). Consumers Report did an interesting expose on this practice a few years ago, and found that many many equipment manufacturers grossly inflate the "power" spec as part of advertising hype.

First there's at least a 3dB difference between peak and average (or RMS) power. 3 dB doesn't sound like much, but that represents half power, so a 500W peak rated self-powered speaker may only deliver at most 250W average. Second is the efficiency of the speaker itself, i.e. how much sound power per watt does it make.

Then there's the issue of the "crest factor" (a measure of the peak-to-average ratio) of real audio, like music or movie dialog. Only a sine wave has an average value that close comes close to it's peak, and not many people listen to sine waves! Real audio probably has RMS (average) power at least 10-20 dB (that's one tenth to one-onehundreth) lower than it's peak, so the 500W peak figure may in practice translate to an average draw of only a few watts, depending on how efficient the amp and its power supply is.

That kind of glosses over some details, but might explain why a self-powered speaker rated at "500 watts" may sound very loud while drawing only 5 watts on average from the AC power line.