I have a couple questions about my DIY LED installation.

  • Both FUSE BLOCKS have 20 amp fuses inline each input to the main terminal which leads to the PSU, so 6 to 1, each having a fuse inline such that both live and return have fuses.

  • Also I have ran this in real-world testing with my DMM so my math is of real world experience, these are visual lights so not full white. Also I limit them to 200 out of 255 in programming.

  • The last picture denotes my area of concern: What happens to my math at these posts while configured like I have? Also my lights are powered on one side, so a parallel circuit (right?).

  • Now I have read a lot—I mean a lot— saying to power both sides, but the manufacturer even says you don't need power on both ends, so I choose that route for less soldering and wires.

My lovely Photoshop drawings, enjoy:






Wire AWG INFO: Don't laugh! Grossly overestimated power consumption first round.

  • PSU to TERMINAL BLOCK = 10 solid // can handle anything my project throws at it, the same for below
  • TERMINAL BLOCK to BUS BLOCK = 12 stranded
  • BUS BLOCK to LED STRIPS = 12 stranded superflex (yes I know this is too much; I'm new here)
  • DATA is ran with= 22 awg throughout from IC


  • WS2812B
  • 120 LEDs per strip
  • 2 strips per aluminum extrusion
  • 4 aluminum extrusion strips


  • PSU = 300 watts // project takes approx. 288 watts so 96 percent power comp, little over the 10% mark
  • TERMINAL BLOCKS = 50 amp capacity using 20 amp fuses on both LIVE and RETURN // safety net???
  • LEDs = power consumption per 120 LEDs (pixels) per strip = approx. 6.25 watts // not alot yus
  • 5 volt system, DC
  • Consumption per strip in amps = 1.25 amps // at full brightness roughly it changes with colors
  • 2 strips combined is approx. 12.5 watts // 2 LED strips in an extrusion power consumption

Now in my first picture supplied, not V2, my lights lit up efficiently and safely. I ran them for 24 hours and my wires never got hot. Yes I did overkill (way overkill) on purpose as my solder skills are above average, so no shorts.

Will my V2 work efficiently as the first one when I switch over with the "CONSOLIDATION" of wires with the added second BUS BLOCK, thus bringing the spare LEDs to a BUS BLOCK and freeing up other terminal posts? Now with this alteration, I have connected (2) sources to (1) terminal block that once had only (1) source.

My strips do not have a closed loop // the LIVE and RETURN are only fed at one end.

I'm basically confused about what I'm doing to my circuit. Will it perform properly? I am not interested in changing up my circuit completely, as I have made a bunch of custom wiring for it, but if I am completely lost, please let me know.

Once again, the final question is: Will my (V2) drawing work for my 4 LED fixtures (8 strips @ 120 LEDs) @ 300 available PSU watts?

My math shows I'm at 96 percent at (V1) drawings, but when I make this alteration to the wiring and having two sources on on post, what does that do to my math?

Thank you for reading this and please let me know any material you have vested interests in, as I am always willing to buy a book and learn.

  • \$\begingroup\$ I am limited on time so I will just leave this comment. There are many posts on the site about powering LED strips. In short, you often must supply power to the strip from both ends because of the thin copper used in the strip itself. Sufficient gauge wire (no problem here for you) can carry current more efficiently than the strip. Whether having only 4% of overhead on your PSU is an issue or not comes down to how your PSU derates (does it do so safely?) and whether you intend to run the LED strips at full white and for how long. \$\endgroup\$
    – JYelton
    Commented Mar 28, 2020 at 5:35
  • \$\begingroup\$ Related (powering strips): electronics.stackexchange.com/a/423656/2028 (book list): electronics.stackexchange.com/q/616/2028 \$\endgroup\$
    – JYelton
    Commented Mar 28, 2020 at 5:36
  • 1
    \$\begingroup\$ Finally, your question seems to be missing some words here and there. For example you say "...ran them for 24 and my wires..." Did you mean 24 hours? "my solder skills are above so..." Did you mean above average? It's a minor thing but I had to re-read the question to figure out what you mean. \$\endgroup\$
    – JYelton
    Commented Mar 28, 2020 at 5:38
  • \$\begingroup\$ One last comment: I am not sure if the words "live" and "return" are yours or how the PSU and strips are labeled. Typcially we would refer to these as "supply" and "ground" or "postive" and "negative." "Live" is usually (but not always) used to refer to the live wire in an AC mains setting (contrasted with neutral and protective earth or ground). "Return" is usually used in audio recording (send and return) and in HVAC (air return). \$\endgroup\$
    – JYelton
    Commented Mar 28, 2020 at 5:42
  • \$\begingroup\$ @JYelton Firstly thankyou for your responses while limited on time. \$\endgroup\$ Commented Mar 29, 2020 at 18:44

1 Answer 1


Your diagrams are a little confusing. The effort is appreciated, but the critical bit that's missing is how the fuse blocks are wired.

Consider the following two schematics:


simulate this circuit – Schematic created using CircuitLab

The only difference is the fuse position. From the perspective of the power supply (what you call "live") the fuse is either before the LED strip or after it. They are functionally the same. If current through the circuit increases beyond the fuse rating, it will open and interrupt the circuit.

I don't understand how the "fuse block" is meant to be wired. Typically a block of fuses will have slots for loading glass cartridge fuses, for example, but is not itself a distribution block. A typical fuse block might basically be:


simulate this circuit

On either side you would simply have screw/spade/spring terminals, binding posts, or whatever to attach the wires.

A terminal block as you have at the bottom of your diagrams, is commonly used to make connections between wires. But how the terminals connect to each other varies wildly. A "distribution block" would typically have several terminals connected electrically together, whereas a "terminal block" is just a more general term for these connectors.

For example, here's a terminal block where two wires can be connected to each other, but each set of two screws are isolated:

Terminal block

Compared to a distribution block (or bar), typically used to connect multiple grounds in a circuit breaker panel:

Distribution block

Since you seem to have multiple fuses and LED strips, I assume the intent is to have each strip protected by a fuse, but the entire installation powered from a single power supply.

That would connected as follows:


simulate this circuit

You will have to determine how your particular components are connected and compare them to this suggested schematic.

Usually WS281B (that's the controller datasheet) LEDs are loosely calculated based on 60mA per pixel (20mA per LED). With 120 pixels per strip that's 7.2A, which at 5V is 36W. This is quite a bit more than the 1.25A and 6.25W you used. (These are also commonly called "NeoPixels" due to the popularity of Adafruit's sales and support. I'm not affiliated.)

If two of these strips are combined into an "extrusion" as you mentioned, then each one will require 14.4A or 72W at most.

Four of these extrusions then, would require 288W, which is the figure you listed first with your PSU specifications. So I think your math is ultimately correct, even though the per-strip figures you list later are low.

A 300W PSU should be able to continuously supply its rated power, so in theory your project will operate just fine. You will want to check the PSU documentation to see what it is actually rated for (is it 300 watts, but only at a certain duty cycle, for example?). Consider, for example, the Meanwell LRS-350-5 power supply. It is a member of their "350 watt" power supply line, but if you look carefully at the specifications, the 5V variant is only good for 300W.

Generally I like to have a minimum of 20% headroom, so for this project I would recommend a supply that is genuinely rated for 350W PSU. (Perhaps a Meanwell SE-450 which is rated for 375W at 5V.) It will run cooler and longer and I would feel more confident about it. That said, if you are not expecting the LED strips to run at full white most of the time, you may be just fine.

Some final thoughts: 5 volts from the PSU out to the strips will inevitably have some voltage drops due to resistance. More noticeably from the first to the last LED in a given strip. Your large gauge wire will help cut down on that considerably (from PSU to strip), but if you measure the voltage at various points in your system, you may note that the lowest voltage is at the last LED in a strip (don't be surprised if it's only 4V). This is also why you may see some pink or red gradation in the strips from one end to the other when they are supposed to be at full white. To compensate, try to ensure that power is supplied to both ends of the strip and that power distribution wires are as short as possible. You may alternatively want to use smaller wattage power supplies closer to each strip.


Why Power LED Strips from Both Ends?

You expressed some confusion in a comment about providing power to both ends of an LED strip.

Think of an LED strip not as LEDs connected by copper traces, but instead as LEDs connected by low value resistors:


simulate this circuit

Current-limiting resistors not shown.

If you have a very long strip or very thin copper traces, you may see a noticeable voltage drop on the last LED (furthest from the supply). I did some quick calculations and I would agree that you probably don't need to power your strips from both ends. Just be aware that with long (4+ meter) strips, sometimes it is necessary to connect both ends to power to help avoid this issue. When in doubt, measure!

Redundant Fuses?

By having a fuse block on both the "live" and "return" sides (let's call them positive and negative, since we're working with DC), you effectively have:


simulate this circuit

This seems to only complicate your wiring. If you feel better having two fuses instead of one in the circuit, that is up to you. But my perspective is that you're simply adding additional points of failure unnecessarily.

You mentioned that you chose to power the LED strips from just one end to reduce the amount of wiring and soldering. I think that's perfectly acceptable given the manufacturer's note and the strip length (I assume they are 2 meters or less). You can completely eliminate one of the fuse blocks. For example, I would simply connect the negative terminals of the distribution blocks (or each LED strip) directly to the power supply. The fuse block on the positive side is sufficient.

Multiple Wires from a Terminal

Your last image shows how you've doubled the wires from the positive fuse block out to two terminals and you express concern about doing this. I presume you are running LED strips from each of these wires (one enclosure or "aluminum extrusion" on each wire).

The problem that this introduces is that one fuse is now inline with two strips in parallel. If a strip pulls 14.4A, then two in parallel pull 28.8A. (Current usage is additive when connecting loads in parallel.) This means a 20A fuse will blow when no problem actually exists; in other words, the fuse will be under-sized for the load.

A single fuse should be connected serially with the load it is protecting.

Some Additional Tips/Help

  • Diagrams: You should invest some time learning about wiring diagrams and schematics. It will make your question more clear and communicate to engineers exactly how your project is connected. See this question and answer for ideas.
  • Wire gauge: Your wire gauges seem adequate for your project. You may want to look up "wire ampacity", "wire sizing guide", or "selecting wire gauge". There are numerous charts which will give you general guidelines on how much current various gauges of wire can safely handle (based on length, ambient temperature, whether the wire is bundled or exposed to air for cooling, and allowable temperature increase).

    Looking at your diagram, you have eight total connections from the positive fuse block. Assuming these all connect to LED strips capable of pulling 14.4A each, that's a total of 115.2A. The single wire from your power supply to the positive fuse block then must be capable of carrying that current safely. Your choice of 10 AWG is good here (assuming that it is a short length).

  • Series/Parallel: I think if you have a good understanding of series/parallel circuits, you will be able to answer your own question about the fuses and how you've connected them to one or two LED strips, per your diagram. All About Circuits is a good place to start.
  • Firmware vs Real-World: You mentioned in a comment that you are only using 200 out of 255 for your brightness. This is good, but hypothetically, what happens if your programming has a bug? What happens if someone else modifies your code and thinks 200 is too dim? I wouldn't design a system to depend on a firmware limitation, necessarily. Including fuses is a commendable decision. I have had numerous control systems fail in some weird way where the output signal is either not working or is interpreted incorrectly. If in one of my projects, my lighting operates at 100% brightness due to noise or a software error, I definitely don't want wiring to be the weak point. My advice is to design a system electrically to operate safely at its full potential, and then limit it in firmware as needed.
  • Language and Asking: Here is some more general advice. The StackExchange sites are meant for asking a single question and getting at least one good answer that definitively answers that question. Comments are meant for minor clarifications and for users to critique or clarify. Unfortunately, longer discussions where additional details emerge about a project are not well-suited for the Q&A format. I suggest if you have another question about this project that you ask a new question that focuses on the specific portion of it. You'll get a lot better results with much less to read! (Apologies that this has become a very lengthy answer!) Here, I've had to address numerous concerns, all of which could (and should) be separate questions.

    Last but not least, please try to capitalize, spell, and format as best you can. (I don't know if English is a secondary language for you or not.) For example the pronoun "I" is capitalized in English. Doing so makes questions easier to read and the attention to detail really goes a long way to making your engineering needs communicated clearly and quickly. You can review my edits to your question to see some of the changes.

  • \$\begingroup\$ thank you, but i still didnt get in this at all what happnes to that fuse block post when i hook two sources up to it, the fuse blocks has a fuse inline going to the main terminal on top, so each of the six inputs on the terminal block have a 20 amp fuse, does that clear anything up, i will upload a new sketch \$\endgroup\$ Commented Mar 29, 2020 at 19:04
  • \$\begingroup\$ one more thing, i program my lights for 200 out of 255 brightness so when i did a REAL DMM check of my amps getting pulled from one strip it was 1.25 amps so my figures are to say exact to my own DIY build, the numbers i have drawn are from real world examples of my exact build, also my colors cycle and brightness and such as i bought fully addressable strips not to be on at full white (ws2812b) as you listed so you know the benefits of fully addressable strips, but yes these are used for visual effects... is my question clear now? \$\endgroup\$ Commented Mar 29, 2020 at 19:07
  • \$\begingroup\$ also i am using a ALITOVE 300 watt and ALITOVE ws2812b strips i will be sticking with my materials thank you for your recommendations. \$\endgroup\$ Commented Mar 29, 2020 at 19:09

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