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Grounding for LED illuminated steel structure

Grounding for LED illuminated steel structure

(OP)
Hi guys,
I'm working on a circus arts project where I am designing a steel structure that is to be illuminated and controlled via DMX protocol. The steel structure consists of 1" pipe sections of various lengths, connected together using pipe connectors (Kee Klamps). The structure will look like a kid's playground in which the circus artists will be able to climb in and do all sorts of stuff. Some pipes will be wrapped with LED tape and protected with a translucent polycarbonate shell and will be individually controllable. Our budget is about 25k$ CAD to give an idea of the scale. About 120x 24" pipe sections will be illuminated, each requiring 2A @ 24VDC. I will be running 24 channel DMX controllers, fed by a 24VDC 1000W PSU, but will only run 20 channels per controller to remain below the max 1000W. Each output will be fused for safety. I figure the 6 PSUs will need to run on their own 15-A breaker, or maybe have 2 run off 20-A breakers.

I would like to keep wiring as simple as possible since it's going to be a lot of wires to run through, especially since I would like to hide the wiring inside the steel structure. My question is: would it be acceptable and safe to wire the complete system like a car, in which all components are supplied by a V+ wire, and are grounded directly to the car frame, and the car frame is connected to the power supply ground? In other words, I would have 6x individual PSUs, each feeding their own DMX controller; all DMX controller outputs, being appropriately fused, would be directly connected to the LED tape V+ solder pad, and the LED tape V- solder pad would be connected to the metal pipe itself, which would make contact with the all-steel structure, and I would connect all 6 DMX controller grounds to the structure. Is this safe? Acceptable? Within code?

Also, would you have some standards that you would recommend I read to do this project, regarding safety, wiring, etc? I have only found the standard DIN56950-1 Entertainment technology - Machinery installations - Part 1: Safety requirements and inspections, but I don't have the budget to buy it at 300USD. Any other stuff I could read I would very much appreciate - I can borrow most industrial/commercial standards from our local equivalent to the OSHA.

Thanks!
Georges

RE: Grounding for LED illuminated steel structure

I wouldn't want to rely an a bunch of Kee Klamps for carrying current; you will go nuts trying to track down the high impedance connections.

For reference, note that automobiles typically have a dozen or more braided copper grounding straps to carry current among the major bits, without relying an a structural connection for electrical conductivity.

Mike Halloran
Pembroke Pines, FL, USA

RE: Grounding for LED illuminated steel structure

No, and no. It's bad form to use a chassis to run current for the reason stated above. Additionally, if you do get an open, you're going to be getting some PRETTY impressive sparks and arcs.

"About 120x 24" pipe sections will be illuminated, each requiring 2A @ 24VDC." --> 240A

Are you seriously trying to run 240A through a jungle gym? Even the nominal impedance connections are going to be a nightmare. You cannot tolerate much more than 50 milliohm TOTAL series resistance, which already results in a 2V droop.

TTFN
I can do absolutely anything. I'm an expert!
FAQ731-376: Eng-Tips.com Forum Policies forum1529: Translation Assistance for Engineers

RE: Grounding for LED illuminated steel structure

You would regret not running single returns. Often the LED supplies are not referenced to ground and if they aren't you can end up with perplexing problems.

Keith Cress
kcress - http://www.flaminsystems.com

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