How to Solder Waterproof Wiring to Pixel Strings (Video)

Worried about how to solder your waterproof extension cables to your pixel strings?  Worry no more, the following video shows how simple it is to solder on wiring to your pixels:

The following products were used in this video:

10ft, 3 core extension cable
12v, WS2811 Pixel String
1/8" Heat Shrink Tubing
3/8" Heat Shrink Tubing

A Demonstration of the Effects of Power Draw on Long Lengths of RGB Lights

Todays blog post is about the effects that power draw has on RGB lights.  We've taked about it before in our blog post about how wiring affects power distribution and in our demonstration example house where we lined it with pixels and handled the issue of power consumption.

This video is pretty simple - it shows 160 pixels (480 DMX channels) connected to a single power supply and our HolidayCoro pixel controller.  It is intended to show the effects that the gauge of the power wire and the power consumption of the pixels themselves have on the actual light output.


(open in YouTube with High Def for better viewing)

Post any questions below.

Thanks,
David
HolidayCoro.com

The Nearly Famous RGB Video Series - Everything You Wanted To Know About Pixels But Couldn't Find The Answer

When I started researching RGB and pixel solutions in early 2010, there was just about no information on the internet as to what all the teminolgy, protocols, wiring, controllers and other items were.  After extensive research and work with others, I decided to document all the information I knew at the time in the form of a video series.  The focus behind the videos was to simply show each type of lighting, controller, wiring, etc in a non-vendor specific manner so that someone just getting started out could get up to speed on the terminolgy and functions.  This information, while produced in late 2010, early 2011 is older now, every bit of it is still completely relevant.  Since this information is squirrled away on our website, I though I would repost it here for those new to RGB and pixels.

The videos below cover the general topics of RGB as they relate to Holiday Lighting.

Video #1 What is RGB? What are the different type of RGB lighting devices? What is Basic RGB and RGB Pixels? How to Pixels get their addresses? How do you assign channels to pixels? What are controller macros?
Video #2 How do I fix dead pixels? What is the difference between three and four wire pixels?  Does it matter? How do I know which end of my pixels to hook to the controller?  Does it matter? How do I power my pixels? Why are there different voltages for pixels? What is the difference between centralized and de-centralized power distribution of pixels? How many pixels can be on a single controller output? What is color depth in pixels?  Why does it matter?
Video #3 What are the different type of pixel chips? What quality issues should I be aware of when purchasing pixels? What are the drawbacks of RGB over just regular Christmas lights? What advantage do Basic RGB and RGB Pixels give me?
Video #4 What are the different types of Basic RGB controllers? Why would I want to use basic RGB controllers and LEDs instead of pixel based controllers and LEDs? What are the different types of RGB Pixel controllers?

Outlining Your House in RGB Lights - Detailed Instructions

Updated 25-Aug-2015 with Brilliant Bubs and Updated Spredsheet

In our prior blog article – Outlining Your House in RGB Lights – A Primer we covered the high level decisions that needed to be made when designing system for RGB lights on the fascia of a house.  This article, unlike the first, provides in-depth information on how to layout and spec such a design.  Not included in this article are the specific step-by-step instructions on how to wire controllers, wire power supplies, how to solder or any other physical setup – but don’t worry – that is actually the easy part, it is the design that most people find the more complicated part.  I should also mention, just as our blog article No Free Rides – Cheap Isn’t Free When It Comes to RGB – there isn't an “off the shelf” solution for doing this – each house, each display, each budget and each level of skill is different and the only person that knows all these requirements is yourself.  So, expect to spend some time doing research for a complete solution.

One last thing - if you have not already done so, be sure to start with our RGB Projects Primer post.  This post covers all the major steps you need to consider when designing a pixel based project.

Ok, so let’s get started.  We have selected the house of Nathanial R. to build this real-world sample project from.  This house (shown below) has many areas that need to be covered – 19 in all, so this house will serve as a good example of how a house with many complex roof lines can be handled.

 

Design – Always the first step

Often people try to determine which hardware will fit their house without first starting with a design.  The absolute best method is to always start with a design prior to purchasing anything.  Design can comprise many aspects but in essence it is – What do you what your display to look like?

Normally you would look at the entire house/display and determine all the elements that you wanted to add – mini-trees, megatrees, bush lights, candy canes, cutouts, garland, icicles, borders, etc. and then create separate “projects” to focus on each one.  In this case we are focusing on a sub-element of Nathanial’s display – to outline the fascia of his house with RGB pixel lights.  He has already determined that he likes this look but just isn't sure what is required and the issues involved in the project.

So, start this project by going outside and taking a photo of your house from the approximate location(s) that your viewing audience will view your display.  These photos will serve to allow you to sketch out your design and to also layout measurements, cable routing locations, controller locations and other relevant information.

 

Smart or Dumb?

This is the first major intersection on your project – you need to determine if you want to go the dumb RGB or Smart RGB route.  Here are some of the pros and cons of each for this project:

	RGB Smart/Intelligent/Pixel	RGB Dumb/Basic
Lighting Costs	Smart RGB modules and strip are about 10-30% more expensive than dumb of the same physical items (modules, nodes, strip).	Lights are about 10-30% cheaper than Smart.
Lighting Functionality	Smart RGB lights can be controlled either by individual lights or in small sections (usually less than 3” each).	Dumb RGB lights cannot be controlled individually – all lights attached to a controller will be the same color and intensity.
Controller Costs	Smart RGB controllers are about 50% to 100% more but generally you need fewer since pixels can be used with power injection.	Controllers are less expensive but you are likely to need more of them along with more power wiring.  Long runs are extremely complicated to perform with dumb RGB.
Controller Functionality	Smart pixel controllers are able to control each light or small section of lights individually.	Dumb controllers can only control a string of lights, not individual lights within the string.

Today, in 2015, it is hard to make a good case from going with dumb RGB for a house outline in all but  few cases.  Pixel solutions are easier setup than dumb and the cost differences are minimal when all other factors are included.  If you are going dumb RGB outline, you should know why it was selected over smart.

A few caveats on this – some people would design this using pixels and using either functions in their software or controller, would limit the control to sections or controller outputs.  Some pixel controllers have an option to control an entire length of pixels with just three DMX channels instead of each pixel with three individual DMX channels.  This allows simplicity in setup and sequencing at the trade-off control but still allows moving to a full pixel display later on down the road when you are ready to do so.

For simplicity and brevity, we will be focusing only on pixels in this case since this is the direction that Nathanial has decided to go - though you will find dumb or basic RGB have many similar design requirements (power, signal) but just slightly different hardware (controllers and lights) than pixels.

 

House Measurements

An absolute requirement for this project is to determine where you want your RGB lights to be located.  To do this you will first need to determine where you will be installing them and how you will be installing them.  We won’t delve into specific mounting methods as there are just too many options depending on your house constructions and overall look you are going for – such as under soffit “wall washing” instead of fascia mounted or directly viewable RGB lights.  (See our budget PVC pipe mounting method here and our high-end aluminium mounting strip here.)

So, get out your ladder, tape measure, thinking cap and determine the exact length of each section where you wish to place the RGB lights and record it on the photo of your house.  When you are done you should end up with a photo that looks something like this: 

You can see that he has measured each and every section of the fascia that he intends to mount the RGB lights to.

Why does it matter that you are accurate in the measurements you take?  The reason is that, depending on the RGB lights you intend to use, even just several inches of RGB pixel lights could result in 3 to 6 DMX channels and if you miss a few inches here, a few feet there, your final design could be off several dozen or hundreds of channels depending on the size of your display.  This is not to even mention the issues in properly calculating the power consumption.

 

Selecting RGB LED Types

The next step is to determine the actual type of RGB Pixel LEDs you will be using.  Which pixel type you select depends on a number of factors, such as the density of lights and control you want, the amount of cost you want to expend, the type of “look” you are going for and a number of other minor factors.  Let’s go through some of the areas you should be looking at when you select the type of RGB pixels you intend to use:

·         The “look” you want to achieve – There are a variety of different types of pixels on the market – nodes (with and without diffusers), strip and modules.  You need to determine the type of look you want – is it a more retro look like with C7/C9 diffused RGB nodes or do you like the close spacing in strip that offers a more “neon” appearance?

·         Costs – Each different type of RGB light has different costs.  Some of this cost can be a result of a better quality pixel, level of control it offers or density the RGB lights in the pixel.  Typically, strip lighting is always going to be the lowest cost method of getting RGB lighting onto a house outline.

·         Mounting – Each pixel type has a different method of mounting.  Some may be able to use existing mounts such as those based on C7/C9 devices (rare) or they may require a mounting substrate (PVC pipe, 1"x2", etc).  Think about how you will be mounting the type of RGB pixel you select and what effects it will have on the mounting method and the cost of that method.  Also keep in mind how complex it will be to mount and dis-mount the pixels – saving 50 cents per pixel won’t seem like a great deal if it takes you two times as long to mount them.

 

The Number Crunching

A this point you have now selected the types of lights you want to use and you have collected the lengths of each section on your house that the lights will cover.  The next step is to enter this data into our spreadsheet.  This spreadsheet (requires MS Excel 2007 or later) only requires you to enter each of the lengths (sections) within your project and select the type of light (strip, module, node) you wish to use and it will then output costs, number of RGB and DMX channels and power requirements.  This gets you part of the way toward your final design and it also allows you to play around with different lighting to determine channel counts and costs but it can’t completely design your display because there are just too many factors to take into account.  There are many small but important decisions that need to be made based on the specifics of your house and design.  Here are some of the issues:

·         Location (and type) of controller(s) – There are three basic options for pixel controllers – a centralized controller solution, a de-centralized controller solution and a mixed centralized/de-centralized controller solution.

o   Centralized – These controllers, such as the AlphaPix 4 and AlphaPix 16, are units that take an input of DMX data (over Ethernet using the E1.31 protocol) and output over 4 or 16 outputs (separate strings or DMX universes).  This means that you can hookup a single string of RGB pixels, ranging from 320 (AlphaPix 16) to 680 (AlphaPix 4) pixels per controller output.  There are some issues here though – there is usually a limit to the length of distance between the controller output and the start of your string of lights and these limits vary but are often (with most pixels HolidayCoro sells) around 15 to 20 ft.

o   De-Centralized – These controllers, such as the EasyPix allow you to take an input of DMX data (from a DMX dongle, such as the ActiDongle or from the RS485 output of our AlphaPix controllers (3 on the AlphaPix 16 or 1 on the AlphaPix 4) and output the data to a pixel string, usually up to 170 pixels per controller.

o   Mixed Centralized & De-Centralized – There maybe cases, most often with large houses or wide spaces, where it makes sense to use a mix of these two controller types.
o   Power Management – Just as important as getting a data signal to pixels is getting the proper amount of power to the pixels and there are a myriad of issues involved, such as:

o   Cable/wire gauge – This is a complex issue but it really boils down to ensuring that for the amount of power you will be using, that you have sufficient method to get it to where it is needed and this means using a wire gauge that meets that need.  We've talked about this in our “Technical Guide to RGB Wire Selection” article, so we suggest starting there.  Be aware that the wire gauge involved isn't just that leader cable from the power supply to the pixel but the actual gauge of the wire inside the pixels themselves.

o   Power consumption of each pixel (or group of lights that make-up a pixel) – The spreadsheet will help with this calculation but also be aware that there is a limit to the number of pixels that can be run in a continuous length due to power consumption by the pixels themselves.  Some pixels may only be able to be run continuously in lengths of 40, 50 (common in 5v pixel nodes), 100 or they may be able to take a single injection of power at the start and run for a full universe of 170 pixels (510 DMX channels).  For most of HolidayCoro's pixels, you'll find a information on power consumption and length limits before power injection is required.

This is why you see 12v pixels vs. 5v pixels.  A 5v pixel is closer to the actual voltage of the LED and IC chip using the power and thus is more efficient as where 12v has to be “dropped” down by use of a voltage regulator circuit (not as common) or dropping resistors which waste the power.  The trade off is that you generally can run 12v strings of pixels, given the same gauge wire, longer distances than you can 5v pixels without the need to re-inject power as often.  This is an entirely separate and complex discussion.  In general, you'll find it "easier" to work with 12v RGB lighting which is more forgiving than 5v lighting which requires more accurate planning and power management.

 

The Real World

Now that we've covered many of the basics, we are ready to turn our attention back to Nathanial’s house and start working through the design.  First, we input the data into the spreadsheet (version 2.1 / 25-Aug-2015) and select RGB pixel strip as the type of lighting we want to use (RGB Pixel Strip in this case):

This provides us with some important starting points:

·         The total number of DMX channels is 1,308 and since each DMX universe is 512 (actually 510 for pixels or 3 channels * 170 pixels), we end up with needing 3 universes.

·         We will need a total of 436 RGB sections and/or RGB channels

·         We will need about 324 watts of power

So, now let’s go back to the photo of the house and the location of each section of RGB strip he intends to use:

The first issue we need to address is that with some controllers (does not apply to HolidayCoro AlphaPix controllers) no one continuous length of strip can be more than 170 RGB pixels/channels (510 DMX channels - Red, Green, Blue channels * 170 pixels) in a typical controller.  As a result, we need to look at logical sections that might be a continuous length and determine if they are under 170 RGB channels or less.  If we look at the front section of the garage facing the street, we have a total of 26 linear feet of strip we need to place.  We can see that the spreadsheet has calculated that this is a total of 80 RGB channels – OK, good there, what about if we include the side of the garage over the garage doors at 34 feet.  We get 182 RGB channels – nope, can’t do that, its 12 RGB channels over the output of any single output (170) so our options are to either adjust the lengths and remove a section, or break it down into two sections.  We are going to go with two sections for the garage section – with 80 RGB channels for the front of the garage facing the street and 102 RGB channels for the section of the garage over the garage doors.

We’ll do the same for the top of the house with the sections that are 8.5’ + 8.5’ + 1’ + 9’ + 15’ + 11’ for a total of 53’ linear feet and a total of 160 RGB channels.  Then for the bottom section of the front of the house at 6.5’ + 6.5’ + 9’ + 9’ for a total of 31’ or 94 RGB channels.  So, to summarize, we have the following segments:

·         Garage Front:  80 RGB Channels & 240 DMX channels

·         Garage Entry:  102 RGB Channels & 306 DMX Channels

·         Front House Top:  160 RGB Channels & 480 DMX Channels

·         Front House Bottom:  94 RGB Channels & 282 DMX Channels

You can see these numbers match perfectly to the spreadsheet calculations of 436 RGB channels and 1,308 DMX channels.  Of course this assumes that your controller can handle a total of 170 RGB channels per “output” – adjust as necessary to meet the specific requirements of your pixel controller.

Power Distribution

This is where things can get a little tricky – while we will be selecting a controller that can output a total of 170 RGB channels, that doesn't mean that if we apply power to the start of the strip (in this case), that a sufficient amount of power will make it to the very end.  As power runs down the strip, most of the power is lost to the LEDs using the power and the remainder is lost to the resistance in the strip itself or the wire between modules.  So, we go back to the spreadsheet again and we look at the power consumption for a given grouping of sections.  We get:

·         Garage Front:  60 Watts

·         Garage Entry:  76 Watts

·         Front House Top:  119 Watts

·         Front House Bottom:  70 Watts

Here is where it gets a little grey – you can check with your lighting vendor and they may list voltage drop over a given length of RGB pixel – say, input of 12v, 11.5v at 50 pixels, 8.5v at 100 pixels and 6v at 150 pixels but that isn’t common, so more than likely you’ll need to measure this yourself.  How you do this is:

·         Hookup a section of RGB pixels, say 50 or 100 to your pixel controller

·         Using your sequencing application, the built in test function of your controller or a test tool like xLights, output a solid white to all the lights on the section you are testing.  I’d recommend leaving it on for 15 to 30 minutes to let it warm up, which will result in a slightly higher power drop.

·         Using a multi-meter/VOM, measure the voltage coming directly out of the controller to the lights – record this voltage

·         Again, using the mutli-meter/VOM, measure the voltage coming out the last pixel on the string – record this voltage

You should notice a drop in voltage at the end of the pixel section.  How much of a drop is bad?  Well that depends.  Usually less than 10-20% is ok, over that amount you could run into problems either with a dimming of the lights at the end of the string or in the worst case, if the voltage drops low enough, below that required by the IC chip to operate, your pixels will have “random” failures as the voltage fluctuate from high to below what is required for the IC to operate.  This is why running 12v pixels can sometimes be less fraught with issues than 5v pixels.  For example, look at these hypothetical voltage drop examples:

·         Input:  12v / Output:  7v | 5v total drop – A total drop of 41%

·         Input:  5v / Output: 3v | 2v total drop – A total drop of 40%

So, even though the 12v pixels dropped a higher voltage, it was still the same percentage of drop when compared to the 5V dropping to 3v.  Now this is where it gets a bit complicated.  Say that the power has dropped to 3v at the end of that hypothetical string of 5v pixels – normally a pixel chip requires around 5v of power to operate but some pixels actually can take lower levels of power and still maintain operation and a the same level of light output.  For example, WS2801 pixels can run on voltages from 3.3 to 5.5v DC (12v strings that use 2801 drop the power down by using resistors) and maintain a constant current to the LED (thus ensuring they are all the same brightness) but TM1804’s are constant voltage and the LEDs will dim over long runs without power injection.  There are also side issues such as power losses on 12v pixels but that maybe a mute issue for those in snowy areas that find value in a “heated” pixel.

We would always recommend testing your build before and after construction because nothing will be more frustrating than putting all this up only to learn that you’ll need to re-wire it because of power issues.

What do you do if the power drop is too great?  We’ll you’ll need to split the power about half-way down the line, and then using a higher gauge wire (14 AWG and up is always a good start) from the power supply up at the start of the string, carry the power down to the split – the data will pass right through (it is regenerated at each pixel).  This diagram shows and example of the power injection:

 

Controller Placement

We’ve already touched upon the three different types of controllers – centralized, de-centralized and a combination approach.  Now it comes down to the actual placement of those controllers.  There are three additional major items to consider here, other than the controllers themselves – where the DMX is coming from (and how much it costs), the overall cost of the controller(s) and distances from controller to the strings they are driving.

DMX Signal Source – There are two major methods of DMX signal generation:

·         Serial based DMX output dongles – these devices (such as the ActiDongle) connect to a PC via a USB port and appear usually a as “COM” port or similar interface.  Each dongle outputs 512 DMX channels to an RS-485 line (see our blog article on RS485.)  These are used with controllers that take a DMX over RS485 connection.

·         Ethernet based DMX output – some controllers (AlphaPix 4 and the AlphaPix 16) take a direct Ethernet connection into the controller and use the E1.31 protocol which is basically DMX running over TCP/IP (running over Ethernet.)  While somewhat more complicated to setup, E1.31 offers huge numbers of DMX universes in a single data cable.  This means that you could have as many as 16,320 DMX channels on a single CAT5 Ethernet cable to a single controller.

Controller Costs – In almost all cases, it is less expensive to hook up a E1.31 based controller to drive pixels (as low at $129 USD) vs an RS485 based dongle ($50) and a pixel controller ($40) - the difference being that the E1.31 controller could handle 2,720 pixels and the RS485 based controller could only handle 170 pixels. 

Here are some of the thought processes I go through when looking at this design:

·         If the controller supports forward or reverse addressing, I'm not limited to putting the controller on the left side with the strip going to the right (left right addressing is easier and more common.)  So when I look at the house I see at the front corner of the garage two different start/ends occur which could allow me to place one dual output controller there along with a power supply.  I also see the same thing above the front door where the top of the bottom sections of the house come to two points.  All HolidayCoro pixel controllers support forward and reverse addressing.

·         I know I’ll need four outputs since we have already determined that we need four separate sections of strip.  I also can tell that I need to keep the strip under about 30ft to avoid power problems so for the section on the top of the house (30 LED/10 ICs or Pixels per Meter) I’ll need to do power injection but for the other sections I should be ok for power injected at one end of the strip.  Again, you'll need to do your own testing here to determine maximum length.

·         I could place a single, centralized controller on the wall above the front door but I need to consider that it will have long lengths from the controller to the start of the strings (much more so for the string on the front of the garage) and while I could use ghost pixels to repeat the distance, I still would be using a large controller in an awkward spot and I would have a controller with a lot of extra outputs that I won’t use (in this design.)

·         I could use single or dual output controllers and place them at the corner of the garage and above the front door and that would remove my issues with distances but would still mean that I would have controllers in an awkward spot directly in the front of the house.

So, what was the final design decision?  A centralized controller.  This was selected for the following reasons:

·         Ghost/Phantom/Null pixels can be used to repeat the signal from the centralized location where the controller is located to the start of the string.  That resolves the issue with distance (within reason.)

·         The additional outputs of the controller (16 outputs total) can be used for other elements within the display.

·         In this design the power requirements (324 watts) match up well with a single 350 watt power supply.  This isn't to say that more power could be required - test, test, test!

·         This allows a E.131 connection without additional dongles – so one cable for all the channels required.

Here is a photo showing the final layout:

·         The green lines are power (12v DC in this case) using a minimum of 16 AWG wire

·         The purple lines are data (SPI) signals from the controller to the strip

·         The green circles are where power injection on the strip occurs

·         The blue square is the 350 watt power supplies (or supply)

·         The red square is 8 to 16 output pixel controller

·         The orange lines are the pixel strip

·         Black dots are estimates for locations of null/ghost pixels

Our overall hardware costs for this project are:

·         $175 for AlphaPix pixel controller

·         $325 for RGB pixel strip (30 LEDs/m) or $2.25 per foot / 144 ft

·         $40 for 12v, 350w power supply

·         $70 for misc wire (extensions and bare wire)

·         $30 for waterproofing enclosures and mounting hardware

·         $60 for mounting substrate and clips (estimate)

·         $70 misc additional costs (screws, connectors, etc)

·         $770 Total

So there you have it – while this is a very lengthy article for a blog posting, it doesn't encompass EVERY feature, function or possibility – this article should help you work out the major issues in completing a project of similar nature.  You will also notice that we have not even covered the software side of this project – setup of E1.31, configuration of the channels within a sequencing application or even issues involved with sequencing 1,308 channels which is a project unto itself.  We hope to tackle this issue in future blog articles, so stay tuned!

Please note that due to the number of requests we receive, HolidayCoro is unable to provide free design services due to the amount of time it requires to evaluate each individual solution.  We do however, offer consulting services if you should need them.

Thank you,
David
HolidayCoro.com

27-Mar-2016
Here is a follow up video that shows a design process using RGB nodes:

A Technical Guide to (RGB) Wire Selection

With the advent of RGB lighting, there is a need to now carry power over wires that are different than those the community has used in the past for AC based power - namely SPT1 and SPT2 cords.  There are a variety of factors to consider when determining the type of wire you want to use for wiring RGB lighting - whether it is for smart/pixels or basic/dumb lighting:

• What is the amount of current required for the lights?
• What are the conditions the wire will be used in or with? (water, UV exposure, temperature range, how much flex will it be exposed to)
• Cost - not only for the wire itself but also the connectors used with it.
• Availability
• Easy of use (soldering, crimping, etc)

Current Carrying Capacity
First, lets start off with the most important function of any wire - it's ability to carry power.  The primary method of expressing power carrying ability of a wire is in amps.  But...you need to look at the voltage also.  For example, a wire rated to carry 1 amp of power (it doesn't matter is the power is DC or AC):

• 1 amp at 5 volts is 5 watts (Current  or amps * Voltage = Watts)
• 1 amp at 12 volts is 12 watts
• 1 amp at 120 volts 120 watts

So, as you can see, the actual power (watts) a wire can carry varies based on it's voltage (this is part of the reason some people choose 12v RGB lights over 5v pixel lights).  This is the same reason that a high tension power wire for interstate power transfer is in the millions of volts - if the same, 1" diameter cable was at 120 volts as opposed to millions, it would have to be massively larger (in diameter) to carry the same amount of power.  So - volts matter.

So, how to do you know how much current (or amps) a wire can handle?  Well, it's complicated and at the end of this article we will show you the "real world" method to determine what wire you need to use.  There are a number of factors that go into the calculation - including material type (tin, aluminum, copper), design (stranded vs solid wire), the diameter of the wire (gauge or in the US, AWG), the temperature the wire is exposed to, how many wires are bundled together and the insulating material.  You can start with charts, such as this one that give you a rough idea of how much a SINGLE wire can carry - remember that there are always two wires required for AC and DC wiring systems.  When you look at a chart you want to find the AWG (American Wire Gauge) or gauge.  How do you know what gauge the cable is?  Well, it's complicated also for the following reasons:

• Some vendors lie about the gauge of cable - this is very common for wiring sourced from China.  This is most common with wiring used in RGB lights. 
• The charts most often assume you are using solid copper - the best possible (short of gold and silver) conductor of power but often due to cost reasons, you may have tin wire plated in copper or aluminum wire plated in copper or some other variation, which renders the tables invalid.

So, we would always recommend looking closely at the cable and then measuring the cable diameter with a micrometer if you have them.  If you are using CAT5 cable or other cable purchased in the US on a roll, it's usually safe to trust the AWG listing.  So, now you have your wire gauge, say, 18 gauge or AWG.  So, we look up on the table for 18 AWG and find that it can handle 16 amps per wire for "chassis wiring" or 2.3 amps for "power transmission".  Those are some pretty big differences - why is that?  Again, the difference is due to the use of the cable, insulation and other factors. 
Conditions The Wire is Used In
There is no one perfect wire because the conditions that each project it is used in vary.  For example, one person may be permanently installing lighting onto their house and does not have intentions to remove it.  In that case, issues of UV exposure (which breaks down the insulation on the cable) and temperature exposure become important factors.  In this case you might also consider using a solid wire as opposed to a stranded wire as there will not be much future movement (and thus breakage) of the wire.  For installations in very cold regions, the insulation material is an important consideration as common insulation's are made from vinyl which doesn't function well in low temperatures.

So, when selecting cable, consider how the cable will be used and select a cable that meets those specific environmental issues.

Cable Cost
Of course a big factor in cable selection is cost.  The major cost in any cable is the wire, which is most often copper.  You don't want to select a cable that has conductors that are too thin and thus unable to carry sufficient current but you don't want to have overkill as this results in higher costs, heavier cable and often less flexibility.  Also keep in mind that cable cost is also a function of the quality of the insulation, so if you cheap out on a cable that doesn't have UV resistance and the cable has to be replaced after two seasons (along with all the associated soldering and connections), you may not have saved that much in the long term.

Availability
There is always a "right" cable for every need out there in the market, though often those "special" cables are so expensive that the "right" cable can't be used.  So after determining what gauge and insulation that is required, see what vendors carry that cable.  Often moving to a more "standard" cable, such as in the case of CAT5, results in many more vendors, greater competition and as a result, lower costs and higher availability.  So, don't rule out a cable that is close to the specs you need.

Ease of Use
This is one of the least considered factors in cable selection.  Easy of use includes a variety of issues, such as:

• Can the cable be purchased with pre-attached and tested connectors?  This is common with CAT5 and SPT cables which are standardized in wiring, color and design. 
• How easy is it to attach connectors?  Some wire can be very hard to work with due to the small gauge, multiple layers of insulation, strain reliefs or other factors.  Having to attach connectors to each cable, correctly (to prevent possible mis-wiring related damage) can often take a considerable period of time depending on the number of cables you need.
• What types of connectors can be used and do they meet your needs?  CAT5, for example, is ubiquitous and has many types of splitters / combiners, connectors (female / male, etc), waterproof and non-waterproof and more.  If your design calls for direct attached cable, such as screw terminals, is the wire strong enough to handle multiple screw downs on it?
• Connector costs is one of the biggest factors.  Usually in most systems you will have a connector based system for hooking up elements as they are, in the Holiday Lighting world, temporary in nature.  So, while a spool of cable might be cheap up front, if it requires expensive connectors, the overall cost of that connection method goes up and the connectors could be more expensive than the cable itself.  Be sure to think end-to-end on what you need from your connector - does it need to be waterproof or just water resistant?  Does it matter if the connection is water resistant at all (such as the case with SPT cord.)  Don't spend money on waterproofing connections that don't benefit from it.

The Real World Example
So, I've discussed a variety of the issues you should consider on how to select a wire or more specifically, a wiring "system" - how does this work in the real world?

Let's say that you want to hookup four flood lights to a single controller.  We will be using 100ft of cable between the power supply and each flood, resulting in a total of 500ft of cable between the start (power supply/controller) and the last flood.  What cable do you need and what factors would you consider?  They are:

• What is the power consumption of the flood?  Well, maybe the vendor says this is a "10 Watt" flood.  What does that mean?  Does the flood REALLY use a total of 10 Watts?  Well, don't trust your vendor - get our your multi-meter / VOM and actually measure the current draw of the single flood.  We have an article on our Knowledge Base that describes this process and here is a video that you can follow to learn how to do it:
  
  After you have the actual power consumption of a single flood, you can then determine the overall power draw.  So, lets say that the flood actually did consume 10 watts of power or .833 amps at 12 volts or a total of 2.5 amps at 12v DC for all four floods.
• Knowing the current consumption of the flood lights is just part of the equation - now you need to determine the power consumption of the cable itself.  Wait...what?  Yes, the wire itself uses the same power that is used to power your lights.  Think about a water hose - if you hook a few 100ft sections of water hose together, you'll end up with a pretty low water "pressure" (aka voltage) at the end of the hoses, compared to the pressure coming directly out of the faucet.  The same applies to your power supply - if you have a power supply that provides exactly 2.5 amps of power at 12v DC, you will need even more power just to replace the losses from the cable itself. 
• So, what do you do?  You have two options, you can choose to waste the power by using a thinner wire (wire diameter/thickness goes down as the gauge goes up) and just purchase a larger power supply to "over come" the losses in the cable (up to a point) OR you could purchase a lower gauge wire (thicker) that more efficiently carries the power and results in few losses.  This is why when you look at the wire gauge table, you will notice that there is a rating that references "ohms per ...".  Ohms is a measurement of the resistance that the cable puts up against the power flowing through it.  Of course as you can imagine, a smaller diameter cable will have a higher ohms per foot rating than a thicker, larger diameter cable. 
• So, what do you do with this ohms per whatever rating?  Let's take an 18 AWG wire - it has about 6.3 ohms of resistance per 1000 feet or 3.15 ohms per 500 feet - the amount of cable we will be using in this example.  So, we will put these values through an ohms law calculator and we come up with a number of .48 watts.  That means for each wire (we need two) we will loose .48 watts or about 1 watt total for the entire length of the cable pair.  As such, we would then need to add the 1 watt of power consumption from the cable to the total power consumption of the floods (40 watts) for a total of 41 watts. 
• So, say you have a larger power supply, maybe 100 watts and you wanted to reduce your wiring costs and use 24 gauge wire - could that work?  Let's see.  24 AWG looses about 25 ohms per 500 feet for a total loss (per pair of wires) of 5.7 watts, plus the 40 watts for the floods, for a total of 45.7 watts - so you are good to go - right?  Nope.  24 AWG can carry about .6 amps per wire, for a total of 1.2 amps of power carrying capacity per pair or about 14.4 watts total.  So, 24 AWG is out because it just isn't large enough. 
• But wait!  What if you were using CAT5 which ccommonly uses, eight, 24 gauge wires.  If you use two wires for the DMX signal, that leaves you with six, 24 AWG wires - is this enough?  The total current carry capacity of the six wires is 3.6 amps or 43 watts.  That's a little tight for four, 10 watt floods, so what losses does the cable have over 500 feet of cable?  Again, it has a loss of 5.7 watts per pair or about 17 watts total.  Add the 17 watts to the 40 watts and you have 57 watts which is "iffy" on a cable designed for about 43 watts at 500 feet. 
• So, what if you use it anyway?  Will something bad happen?  It depends.  The more overloaded the wire is, the higher its resistance will become, so where there is some head room, there isn't a free ride here.  What will occur is that you'll end up wasting power (about 15-20 watts) that you would otherwise have not wasted...but maybe the CAT5 cable was much cheaper than the purchase of the 18 gauge cable and that difference was much greater than the cost of the lost power (and the larger power supply to provide that power).
• Here is a simple test - take a VOM or multi-meter and measure the voltage at the power output from the power supply and then take a second measurement at the end of the cable, with all items turned on with full output (white for RGB lights) and compare the voltages.  Let's say you start off with 12.5v at the power supply, you may end up with 10v at the end.  Is that bad?  Well, it depends on your controller and lights.  You *might* notice a drop in light output on the 4th flood verses the 1st flood or you may not - it all depends.  Some controllers will have no problem running on that 10v, some others may not be able to handle that drop.  This is most common on pixel strings where you can see 50%+ voltage drops.

So, after all that you can see that there is no one single "best" answer as to what wire you should use or how many items you can put on a length of wire - there are a number of factors to consider and what we always recommend doing is using the math and ohms law as a starting point, building your design and then testing voltages and power consumption of the devices to determine if the cable is overloaded or has too large of a power drop.

Feel free to post additional questions on the feedback section.

Thanks,

David

HolidayCoro.com