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Thread: Wire gauge needed for 24amp load per bank

  1. #1
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    Default Wire gauge needed for 24amp load per bank

    Having a tough time with this. 4 mini trees per power bank @100 rgb nodes each, I calculate my amp load to be 24amps. Board is a cmb24d used with vixen. No issue handling the load. My issue is with the wire gauge between the power supply and the controller. From what I've read and heard, I should have a slight cushion. 10 gauge is rated at 30 amps, 12 gauge is below the 24 amps mark. When trying to use the 10 gauge solid wire, it's FAR too stiff and putting strain on the connections on the board and psu. It's so rigid that it can hold up the board horizontally without dip! So I went stranded.... The girth barely fits under the power bank screw, and I am left with ALOT of wire after tightening it moderately. Probably half of the stranded wire is outside the screw, and it won't take much movement for that stranded wire to seperate and effectively leave a section of the wire frayed or loose. What the heck do I do?

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    Default Re: Wire gauge needed for 24amp load per bank

    If the 12 Gauge would fit, and is flexible enough, and you have 90 degree C insulation and it is copper, use it....it can handle 30A without an issue.

    Did you consider Voltage drop? You may need the #10 or even more copper.....in that case, splice a short piece of 12 gauge to the xx gauge. A piece long enough to get flexibility, but can remain in the enclosure so you keep the joint waterproof. 1-2, 3 feet each end, of 12 gauge would be no problem. Just calculate in your voltage drop.

    I like to use 80% load, but 90% works too, but then there are places you may need to push the limit, so your short flexible end could be #14. It's rated 25A with 90C Insulation. But expect it to feel warm.

    Note: for voltage drop, you do not need to carry the same size conductor end-to-end. Weakest link(s) needs to be rated at or above rated full load.

    Edit: As Plasmadrive mentioned; connection points are a concern when you cannot verify their temperature rating, or it is known to be low......in these cases, splice to 2-conductors. So if you are running 12 gauge at 90C, then go to 2-#14 - that would split the current to 15A per wire that is 60C rated for 20A.

    Also adding plasma'a disclaimer to what I wrote: "Disclaimer"... what you do is up to you.. this post is not suggesting anything, only offering opinions. You are responsible for what you do and how you do it.
    Last edited by mrGrumpy; 10-11-2017 at 11:28 AM.
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    Default Re: Wire gauge needed for 24amp load per bank

    MrGrumpy has some good points.

    There are a couple of things to really keep your eye out for. First off, technically your wire must be rated to take the full load of the available current. So if you have a 30 amp supply you should either use #10 wire or fuse for your branch circuits to protect the wire size you use on each branch. (It's a code safety thing yadda yadda yadda). Second of all, the voltage drop is real important. You need to make sure you don't drop too low under the max load. #10 wire may be rated for 30amps, but that doesn't mean you can go a long way and not suffer some voltage drop. How much drop is allowed for your application is something to keep an eye on. Personally I run 24v supplies and use DC-DC converters to regulate right at the pixel string. It allows me to have longer runs without the worry about voltage drop and use only the size wire I need for the supply.

    The wire will take 100% of what it is rated for current wise. You don't have to derate it based on that. You do have to watch out for that voltage drop, but you also have to consider what your connections are rated for temp wise. If you have 50C rated connectors, you are not supposed to use a higher temp rating to calculate the allowable load current. (Again its a code thing yadda yadda yadda).

    NOW, lets get to the practical side of this.. You are doing "blinky flashy" which means your load's average current will not be anywhere near ratings of the wire. So unless you keep stuff "on" long term, your wire probably won't even get warm, especially outside and not in any conduit. However, safety wise, watch the current limits as they can bite you in the back side should something go wrong...(fuse where appropriate). Watch the voltage drop so you don't get yellowish whites or cause flicker due to low voltage.

    I will be running static 4 nights a week this year with flashy blinky only 3 nights a week. For me that means I have to build for 100% duty cycle because it will be on for hours at a time with full load in many cases. That may not be your case and you should go from there...

    "Disclaimer"... what you do is up to you.. this post is not suggesting anything, only offering opinions. You are responsible for what you do and how you do it.

  5. #4
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    Default Re: Wire gauge needed for 24amp load per bank

    Quote Originally Posted by XmasinVancouver View Post
    Having a tough time with this. 4 mini trees per power bank @100 rgb nodes each, I calculate my amp load to be 24amps. Board is a cmb24d used with vixen. No issue handling the load. My issue is with the wire gauge between the power supply and the controller. From what I've read and heard, I should have a slight cushion. 10 gauge is rated at 30 amps, 12 gauge is below the 24 amps mark. When trying to use the 10 gauge solid wire, it's FAR too stiff and putting strain on the connections on the board and psu. It's so rigid that it can hold up the board horizontally without dip! So I went stranded.... The girth barely fits under the power bank screw, and I am left with ALOT of wire after tightening it moderately. Probably half of the stranded wire is outside the screw, and it won't take much movement for that stranded wire to seperate and effectively leave a section of the wire frayed or loose. What the heck do I do?
    24 amps maybe if running at 100% and running all white. You can drop that load by running the pixels at 50% (either in your software or at the controller) and not notice a drop in the brightness of your pixels. For the stranded wire, I use bootlace ferrules. Makes a solid connection and you don't have to worry about the connector coming loose.
    That's a feature not a bug.
    There's no charge for that.

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    Default Re: Wire gauge needed for 24amp load per bank

    Quote Originally Posted by Keith R View Post
    snip.... For the stranded wire, I use bootlace ferrules. Makes a solid connection and you don't have to worry about the connector coming loose.
    This logic does not apply to those of you that are "limp wristed" when you make connections..

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    Default Re: Wire gauge needed for 24amp load per bank

    Quote Originally Posted by plasmadrive View Post
    This logic does not apply to those of you that are "limp wristed" when you make connections..
    I disagree, and I hope you are not implying that I am "limp wristed".

    Edit:
    Quote Originally Posted by XmasinVancouver View Post
    So I went stranded.... The girth barely fits under the power bank screw, and I am left with ALOT of wire after tightening it moderately. Probably half of the stranded wire is outside the screw, and it won't take much movement for that stranded wire to seperate and effectively leave a section of the wire frayed or loose. What the heck do I do?
    Merely offering an effective way of using a screw down terminal when the OP is concerned about fraying wires, and tinning the ends is not the best solution.
    Last edited by Keith R; 10-11-2017 at 11:43 AM.
    That's a feature not a bug.
    There's no charge for that.

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    Default Re: Wire gauge needed for 24amp load per bank

    Quote Originally Posted by plasmadrive View Post
    .......... If you have 50C rated connectors, you are not supposed to use a higher temp rating to calculate the allowable load current. (Again its a code thing yadda yadda yadda.)
    As Plasmadrive mentioned; connection points are a concern when you cannot verify their temperature rating, or it is known to be low......in these cases, splice to 2-conductors. So if you are running 12 gauge at 90C, then go to 2-#14 - that would split the current to 15A per wire that is 60C rated for 20A.
    In Lights Therapy...

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    Default Re: Wire gauge needed for 24amp load per bank

    Quote Originally Posted by mrGrumpy View Post
    As Plasmadrive mentioned; connection points are a concern when you cannot verify their temperature rating, or it is known to be low......in these cases, splice to 2-conductors. So if you are running 12 gauge at 90C, then go to 2-#14 - that would split the current to 15A per wire that is 60C rated for 20A.

    Forgive me, I am extremely tech oriented, but more or less a newb with electric theory. If I am reading that correctly, the suggestion is to step down a gauge in wire and double the wires at the lower gauge? Twist them together? If so, this is what I tried originally. An online calculator told me that 4x 16 AMG wires would equal the amp carrying capacity (roughly) (or at least the cross sectional area) of a #10 AWG wire. Since I couldn't find other stranded 10 AWG locally, I "made" it with 16 AWG SPT-2 wire, and this is what was falling apart. Having said that, it was a pretty good twisting job. Or am I completely misunderstanding this?

    Also, to the comment to run the pixels at 50% and there won't be noticeable difference...how does that work? How could you not notice half brightness?

  10. #9
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    Default Re: Wire gauge needed for 24amp load per bank

    You said four trees? I would run a 16 awg wire from the PSU to each tree.

    2017 adding 2 more candy canes, 7 Mid trees and a Halloween show. Removing most 2812 strips and replacing them with bullet pixel mounting strips. Replacing many buck converter waterproof bags with printed boxes.

  11. #10
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    Default Re: Wire gauge needed for 24amp load per bank

    Quote Originally Posted by XmasinVancouver View Post
    Forgive me, I am extremely tech oriented, but more or less a newb with electric theory. If I am reading that correctly, the suggestion is to step down a gauge in wire and double the wires at the lower gauge?
    First, lets scratch the word suggesting, and replace with "consider look into"
    I would not go to 4-#16 SPT-2. too many conductors and I think too fine and too many wire strands. Home Depot & Lowes are all over the place, look at #14 THHN Solid. A little stiff, but fits the transformer terminals better. One left of the screw and one on the right. 2-#14 are the same so the screw will crimp both with the same torque. Make sure this and all connections should be very tight.

    Twist them together?
    I don't . If they are long runs, I get jacketed cable. But a little twisting won't hurt. Since you are just holding all the strands together, use just enough twists to do just that. Makes it easier if you need to replace a wire later.


    Also, to the comment to run the pixels at 50% and there won't be noticeable difference...how does that work? How could you not notice half brightness?

    Not my statement, but I'll comment. For me 100% is too bright so I have started using the reduced brightness this year....I haven't set my final level...feeling 50% is too low, I'm tinkering around 70%. Not saying 50% is bad, I just haven't got that warm fuzzy feeling with using it yet. When the show is up and running I will do more testing.
    In Lights Therapy...

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