Power concerns for multiple LED strips, arduinos and power supplies

Other Hardware LEDs and Multiplexing
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I've attached a rough proof of concept.

What I'm working with:

  • 1 router
  • 4 arduinos with ethernet shields
  • 25 LED strips, each 3 meters in length, 60 LEDs per meter (WS2812B)
  • 5 PSU's (each 5V 60A)

I have a lot of experience with a similar setup, but just one strip per arduino. The LED strip has 5 wires, two sets of power lines and a data wire. One set that goes to the PSU, and the other that goes to the 5V and GND pin, which also powers the arduino. Then the data wire goes into one of the digital pin.

My concern is now that I have multiple strips coming from one arduino (each arduino will get 6 strips, with one of them getting 7 strips), so all the power wires that would go to the arduino, do i instead route them to a single board (breadboard / prototyping), have all the 5V hooked up on one line and all the grounds hooked up on another, and connect the arduino to that respectively. Or do I still just use one strip to power/ground the arduino? Maybe I can skip even hook up power lines to the arduino like that, and just use USB power?

Another concern is that since I'm using 5 PSU's to power the system (since each strip will take at most 10.8A [but rarely, if ever, go that high], that means i can power 5 strips per 60A PSU), it means the arduinos will have strips connected to them that don't share the same PSU. Is there any issues with this?

Another concern is just the technical aspect of distributing power. Each strip will be powered at 1 meter intervals to assure even lighting and no drops in voltage/amps. That means 15 (+) wires and 15 (-) wires will have to connect somehow to the PSU. I'm not too familiar with what equipment I need to buy and and the best practices for using it. I plan on having a 1000 µF cap for each connection though. Any advice or links would be very helpful.

So I get that the ground for everything has to be shared/common, so all the electricity should originate from the same outlet. In total the strips could draw a max of 270A, which i'm not sure how outlets are rated and how much they can handle, so maybe use a couple of outlets. But then, the outlets having a shared ground (which hopefully they should since they'll be in close proximity to each other in the same room) is a concern. I'm also located in China, where I don't think the electrical installation standards are very well adhered to, i've definitely encountered weird situations which make me question it.

Let me know if anymore information is needed.

Thank you.

setup.jpg
setup.jpg2000×2000 583 KB

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Powering NeoPixels | Adafruit NeoPixel Überguide | Adafruit Learning System has good discussion on power requirements

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That page is very informational, thanks, but it doesn't really cover the issues with multiplexing (i think that is the correct term? I just saw it being used around this forum, but most a small projects run off of breadboards. Looking for more solid large scale installation equipment. I guess I'll do a forum search and see if i can turn up any good threads for it). If anyone has good suggestions concerning this or links i could read, that would be helpful. I'll be expanding my search terms as well and seeing what i can come up with on my own.

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One set that goes to the PSU, and the other that goes to the 5V and GND pin, which also powers the arduino.

No that is not what they are used for.

do i instead route them to a single board (breadboard / prototyping), have all the 5V hooked up on one line and all the grounds hooked up on another, and connect the arduino to that respectively

Yes, although forget solderless bread board, it can't handle the current and in inherently unreliable.

Another concern is that since I'm using 5 PSU's to power the system

If that is so you must NEVER connect all the 5V wires together but always connect the ground wires together.

so all the electricity should originate from the same outlet.

No need for that.

But then, the outlets having a shared ground

That is totally irrelevant because a PSU is not normally connected to the ground.

In total the strips could draw a max of 270A, which i'm not sure how outlets are rated and how much they can handle,

The current draw is only part of the story. Work with power. Assume an 80% efficient power supply, so 5V at 270A is :- 1350W, then the extra for power supply losses
1350 / 0.8 = 1687.5W
That is the power your outlet has to supply. At a 240V mains supply this would be:-
1687.5/240 = 7A
So a normal ( for the UK ) 13A fused plug will cope.

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Grumpy_Mike:
No that is not what they are used for.

ok good to know. wasn't really sure what the duplicated (+) wire was for, was just assuming it could be used to power the arduino through the +5 pin. In any case, i'm powering the arduino through USB, so no worries about this.

Yes, although forget solderless bread board, it can't handle the current and in inherently unreliable.

See this is the main thing i'm looking for. Examples of type/gauge of wire, and a central wiring system/board that can handle all of this. These are thing i have yet to work with.

If that is so you must NEVER connect all the 5V wires together but always connect the ground wires together.

Ok, i'm guessing that since the arduinos are not powered from the PSU's, there'll be no issue with it having strips connected to it that are powered from different PSU's. I'm also assuming that I should not have a strip be powered by two different PSUs.

No need for that.

That is totally irrelevant because a PSU is not normally connected to the ground.

The PSU i'm using is similar to this: http://rgb-123.com/product/5v-60a-power-supply/
Are you saying that it's not necessary to connect the ground terminal to my wall socket plug?

The current draw is only part of the story. Work with power. Assume an 80% efficient power supply, so 5V at 270A is :- 1350W, then the extra for power supply losses
1350 / 0.8 = 1687.5W
That is the power your outlet has to supply. At a 240V mains supply this would be:-
1687.5/240 = 7A
So a normal ( for the UK ) 13A fused plug will cope.

Thanks for this math, i'll be sure to ask the venue what their fuses are rated for.

6

Are you saying that it's not necessary to connect the ground terminal to my wall socket plug?

Yes.

I'm also assuming that I should not have a strip be powered by two different PSUs.

You can have the strip powered by two different supplies if you separate the 5V connections on the strips. You need to make sure that all the power supplies are powered up at the same time. This could cause a surge to blow your mains fuse but it is unlikely.

Examples of type/gauge of wire, and a central wiring system/board that can handle all of this.

Even strip board is pushing this amount of current. Whenever I have used this sort of thing I use strip board and once everything is built I run tinned copper wire about 20SWG along the back of the strips to beef up the current rating.

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Great, thank you for all the info.

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Are there any solderless components for this type of power distribution, or is it really recommended, when dealing with this amount of current, to use soldered components? I just appreciate the ability to plug/unplug when necessary, because soldering and desoldering can be time consuming and sometimes messy. I asked my chinese distributor what they'd recommend for a power distribution setup and they basically told me to overlap all the wires right in the power supply's terminal. I don't really want to do that either.

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Are there any solderless components for this type of power distribution,

Screw connector "chock blocks"

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Just revisiting this and was wondering what you think about grounding the PSU for this reason (and then using this method):

Although not everyone agrees, I believe that best practice is to connect the negative power supply to earth ground unless there is a specific reason not to. This provides protection against a fault condition in the power supply. Without this connection, an accidental short circuit (or partial short circuit, up to several thousand ohms) in the power supply between the AC hot wire and the power supply + or - would not trip the circuit breaker or GFI. The danger here is that this type of fault could go undetected for a long time. The attached equipment, this case pixels and pixel controller, could all have an unsafe potential relative to earth ground and present a shock hazard that wouldn't be discovered until someone got shocked.

This type of fault, while not common, could result from moisture in the power supply or a component failure, or a wiring error. By having (-) tied to earth ground (NOT NEUTRAL!!), a fault of this type would not be able to elevate the voltage present on the attached equipment to an unsafe level.

Think of it this way: Without the safety jumper in place, you could short the power supply's line terminal (L) to the power supply's (-) terminal and absolutely nothing would happen. Everything would continue to operate, but if you measured the voltage from the pixel ground lead to earth ground, or from metal parts on the pixel controller to earth ground, you would measure 120 volts of AC, an obviously unsafe condition. If the safety jumper is in place a short from (L) to (-) would immediately trip the AC breaker.

Quoted from: DoItYourselfChristmas Forum

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He starts by saying:-

Although not everyone agrees,

Well I don't agree and also the safety standards people don't agree.
His fears are unfounded and break with the double insulation rule of low power devices. So I would say the opposite, unless there is a reason to ground the -ve supply don't do it.