A thousand feet of LED rope light... need help w/power budget

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Strata
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A thousand feet of LED rope light... need help w/power budget

Post by Strata » Sat Dec 24, 2016 7:19 am

I'm planning a fixed art installation that will require between 600 and 800 feet of LED outdoor rope lighting... the generic off the shelf kind. I've been looking at specs for rope light, but nobody seems to publish the power draw of individual strands. I want to spec a small generator for the lights. Any ideas?

I could always brute force this by buying all the lights and hooking them up together via my kill-a-watt device, but I'd rather not buy a couple hundred bucks of lights and then find out my idea is not workable.

I have about 50 feet worth at home.... any idea how I would do the math if I got a power draw figure for those? Just multiplying sounds suspiciously easy, I bet there's loss and stuff, tricky electrical things....

Can I even hook up 1k feet of rope light, or do I need to do smaller lengths and trench extension cords (ugh)?

Thoughts and wisdom welcome, please!
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Re: A thousand feet of LED rope light... need help w/power budget

Post by TT120 » Sat Dec 24, 2016 7:37 am

You can hook your 50' length to your kill-a-watt and then just multiply it out. That will give you a rough idea of how much you'll need. That number won't be %100 accurate but it will get you in the ballpark.
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Re: A thousand feet of LED rope light... need help w/power budget

Post by Captain Goddammit » Sat Dec 24, 2016 10:49 am

It's about a watt per foot.
1000 feet is a lot to run in a continuous string, I'd break it up into thirds or at least half.
If you have 1000 watts power draw, spec a 2000 watt generator. You'll lose a little output on the playa (high altitude) plus it's better not to run at absolute max full-time.
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Re: A thousand feet of LED rope light... need help w/power budget

Post by Popeye » Sat Dec 24, 2016 11:10 am

Strata wrote:I'm planning a fixed art installation that will require between 600 and 800 feet of LED outdoor rope lighting... the generic off the shelf kind. I've been looking at specs for rope light, but nobody seems to publish the power draw of individual strands. I want to spec a small generator for the lights. Any ideas?

I could always brute force this by buying all the lights and hooking them up together via my kill-a-watt device, but I'd rather not buy a couple hundred bucks of lights and then find out my idea is not workable.

I have about 50 feet worth at home.... any idea how I would do the math if I got a power draw figure for those? Just multiplying sounds suspiciously easy, I bet there's loss and stuff, tricky electrical things....

Can I even hook up 1k feet of rope light, or do I need to do smaller lengths and trench extension cords (ugh)?

Thoughts and wisdom welcome, please!
TT120 is right but multiply your figure by 120%. If they are Chinese (not UL/CSA) go higher.
According to Wickipedia LED rope light pulls about 1 W/ft and incandescent pulls about 3W/ft. This should be good enough for this stage of design.
Depending on what you are planning your draw coulf be a lot less. Flashing or chasing lights don't draw currrent during the off cycle. LED's work on DC at a lower voltage and will need power supplys but are generally more rugged (my opinion). Incandescents are easier to set up.
Are you planning on synching with music or any other effects? If so LED's are probably best.
If you post or email some detailor a diagram on what you want to do we could be more help.
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Re: A thousand feet of LED rope light... need help w/power budget

Post by GreyCoyote » Sat Dec 24, 2016 11:54 am

Realistically you are probably looking at about 800 watts, give or take. One Honda EU2000 can handle that with plenty of room to spare. That translates to a real-world burn rate of about a gallon every 5 hours or so.

One item nobody has mentioned is power factor, ie the angle of lead/lag between the voltage and current waveforms. This will be an important consideration. Good power supplies are usually pretty close to unity, but some of the Chinese stuff is as bad as 0.45 or even worse. This can make a whopping big difference in apparent load when you are working from a generator. And the only way to really know what to expect is to measure a specific power supply under loaded conditions before you buy a bunch of them. Or replace the multiple cheapies with a high-quality supply (Iota Engineering comes to mind). Dunno... But something to consider.

Your project sounds epic! I sincerely hope this comes to life on the playa!

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Re: A thousand feet of LED rope light... need help w/power budget

Post by Strata » Sat Dec 24, 2016 5:14 pm

Thanks folks for the great replies.

I've located a source of longer LED strings with chasing effects, and they advertise .85w per foot in their spec. http://www.affordablequalitylighting.co ... -kit-120v/ I would still budget 1 watt per foot tho to leave headroom.

The project is a 50 foot diameter labyrinth that would be lit at night, with a slow chase effect going along the paths. An interactive henge in the middle will need some power too, for lights and controllers (raspberry pi or arduino). Am getting the ballpark figures for lights, yay, now need to ballpark my henge design, once I finish designing it. The henge also does double duty as a generator cage.

My next step is to go out in the park with some stakes and 150 foot lengths of paracord and see how I'd put it together out of separate strings.

Cheers,
Strata
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