HolidayCoro sales/support often sees common, open-ended questions from our customers and here on our blog we post detailed responses publicly so that other people will be able to learn from the decision making process we use to answer these questions.
Today's question is: "I am making 16 pyramids and would like to light them up using 3 or 4 Basic Rectangle RGB LED Waterproof Module per pyramid. The pyramids will be in the front yard each about a yard apart. My Question - should I buy 16x Item #30 Basic 3 Channel RGB DMX Controller or should I buy 2x Item #24 Basic RGB 27 Channel DMX Controller. Is there any advantage to either in this situation?" For this given project it has already been determined that basic or dumb RGB lights should be used as opposed to pixels and this is often the case when an element doesn't need the control that pixels offer or when there are larger distances between elements. So the question becomes - should the basic RGB DMX controller be centralized in the form of a 27 channel (9 RGB outputs) DMX controller or individual 3 channel (1 RGB output) DMX controller in each element? The issue comes down mainly to two factors - cost and complexity:
Cost - The number of RGB lights won't change between the two methods, so we'll exclude that from the calculations, though what does mainly matter are wiring, power supplies, controllers. Also, we need to determine he power consumption of the RGB Modules, which in this case consume about 100ma (1/10th of an amp) at 12v DC - or 16 elements x 4 modules is 6.4 amps total. So, we'll take the number of individual elements here - 16 and do some comparison math with the two options:
Centralized - This method allows us to have one (or two in this case) centralized controllers - the costs involved are:
$26 ($13 x 2) - 45w (3.75amps at 12v) power supply. This solution would power each 27 channel controller with a single power supply. It's a little tight on the power at 3.2 amps total per controller (32 modules per controller) but it should work.
$20 ($10 x 2) - Waterproof housing. The 27 channel controller isn't waterproof, so you'll need a waterproof/resistant housing and this varies by region, water/snow conditions and budget.
$20 (100ft @ $.10 per foot x 2) - CAT5 wiring. You'll need to get the output of the controller out to the individual elements and CAT5 would be a good solution here as the current consumption of the lights is below the current carying ability of CAT5 at a bout 3 to 4 amps and it has 8 wires, so you could double up each wire for the 4 wires required for RGB lights.
~$180 - Total
De-Centralized - This method allows us to have an individual, 3 channel DMX controllers in each element - the costs involved are:
$8 (80ft @ $.10 per foot) - CAT5 wiring. Using the DMX+Power over CAT5 system, it is possible to inject power at the start of the string and again at the 8th element.
$23 ($1.50 x 16) - 3 Way Splitters for the DMX signal+power.
~$201 - Total
Of course there are other minor costs - shrink wrap, solder, tools, shipping, etc and we've not included those in the calculations above. So, on the surface, they look pretty much about the same from a cost basis, so let's take a closer look and consider all the other factors:
Complexity
Interconnections - Left out from above on both are how you'll interconnect the wiring from the element to the controllers.
Centralized - With the centralized solution, you could solder the CAT5 wire directly to the lights in the element and then have elements with 20, 15, 10 and 5 ft lengths of cable coming off them and then you'd fish that wire into the controller case and screw it down to the terminals on the controller. The problems with this solution are that it makes future adjustments in length complicated since you've already set the length of the cable from the element to the controller when you built the element. Additionally, you'll have to deal with elements that have attached wire and then manually wire up each element to the controller, adding to your display setup time. An additional down side to this method is that you also have more wire spread out over your display which can present safety/tripping hazards. The upside to this method is that it doesn't really require any additional connectors - just tin the wires where they go into the controller screw terminals.
De-Centralized - If you've placed the individual CAT5 controllers in each element, that means that you can simply attach a 3 way splitter to each CAT5 plug, then plug in the necessary CAT5 cable between each element (5ft lengths in this case) in a daisy chain arrangement. Then you just build a power injector for each of the two bands of 8 elements and this allows you to run the power and the DMX signal from one element to the next. The amount of wire is limited as it only goes from one element to the next. The down side is that you need to ensure that you control water ingress in to the CAT5 connectors and use a corrosion control spray - usually mounting the controller up-side down under the element would be more than sufficient to manage water ingress. The real beauty of the Power+DMX over CAT system is that you can assembly your display quickly just by plugging into each element to the element next to it.
We often get requests from customers that ask how many lights they can connect to a controller, how many lights can be connected to a controller/power supply, what type of wire they need to hook up their lights and/or controllers or what power supply they should choose - and this blog post will work to answer those questions. This article assumes you are working with RGB lights and using a DMX based, constant voltage (all HolidayCoro controllers are constant voltage) controller, though the concepts will often apply to other controller types. If the following information looks too complicated to learn or you'd rather just "have the answer", I'd recommend against working with a DIY lighting solution because a failure to fully understand the power requirements in some parts of the system can result in damage to the hardware all the way to house fires - and I've seen them both occur - so DO NOT "wing it" here. Alternately, you can pay someone to "run the numbers" or there are vendors that sell plug-n-play systems and while they are not as flexible as a completely DIY system, there will be little to no need to understand power requirements - just plug-n-play.
The key to understanding how many lights can be connected to a given controller, it is important to see the lights and controller as only individual parts in a system that consists of:
Lights < Lighting Wiring < Controller < Power Wiring < Power Supply
Let's work through the chain and examine each part, starting with:
Lights
Purpose: The lights are the final end-goal of any lighting system and they provide the light output for your display.
Selection: Lights are selected on a wide variety of factors - more than can be fully described in this post but some of the factors are:
Physical: You'll want to select the physical format, be that modules (square, rectangle, etc), nodes (8mm/12mm usually) or strip that best suits the mounting method and directional change (going around corners, curves, etc) requirements.
Voltage: LED lights can come in a variety of voltages, usually 5V and 12V DC. There are advantages and disadvantages of both of these common voltage ranges so refer to additional sources on proper voltage selection. In general, you can go longer distances with higher voltage drops with higher voltage lights (12v) than low voltage drops (5v), though low voltage (5v) is much more power efficient and sometimes has brighter output.
Optics: This can include output angle (60, 90, 180, 360 degrees, etc), color mixing (5050 on-die LED, Tri-Color 8mm, three 5mm separate LEDs, etc), light diffusion and many other factors.
Control type: LED's can be controlled via constant current or constant voltage. Constant current controllers are usually designed into dedicated systems like floods and it requires a specifically matched LED or LEDs to a specific controller as where constant voltage controller allows any number of LED lights as along as they are below the output requirements of the controller. For pixel lights - the pixel is always supplied with constant voltage, even if in the chip it is constant current, so for pixels, consider them constant voltage devices.
Lighting Wiring
Purpose: This wiring is either the wiring between each LED light in a string, such as in the case of RGB LED nodes or it maybe a circuit board in the case of RGB strip lights. This wiring brings the power from the controller down to each light.
Selection: There are no "standards" or "normal" wiring types here - each vendors wiring can be different. One vendor may sell RGB nodes with 24 AWG wire (thin) compared to another vendor that uses 18 AWG (thicker) wire and they can look exactly the same. I would not always trust the data provided by the vendor, more so if your supplier is outside the US as they often lie or copy other vendor specs even if they don't match the actual product. In an ideal world, you would want the thickest gauge wire possible as it will be able to best transport the power with the least losses but the reality is that thicker wire is harder to work with (less flexible, harder to solder to circuit boards or lights) and is more expensive, so usually there is some "balance" between cost, weight and the distance needed for the lights to be run over.
Additional information: Ideally, your vendor will list the maximum run on serially/continuously connected lights that can be supported before there is a "reasonable" drop in power. So, for example, you might have one vendor that sells a 100 count string of 12v RGB nodes and they have a voltage drop from the start to the end of the string of 6v - or 50% of the power is used/lost between the start and the end. Then you may have another vendor that has 12v RGB nodes that have a 3v drop over the 100 count string. Again, this could be due to a number of factors - power consumption/design of each LED, gauge of the wire, quality of the circuit board, the type of solder used, the number of strands in the wire, the type of wire (100% copper, tin coated copper, tin only, etc.) So, unless your vendor provides SPECIFIC information on how much power, over a given length at a given voltage the lights use - YOU MUST TEST AND MEASURE THEM YOURSELF! Don't go by estimates or guesses - only trust the data. When you've collected the power consumption amounts, you should then have a amperage (at a given voltage) or wattage for the number of lights or length of lights. An example of this may be 37 watts per 5 meters of RGB strip.
Additional information: You should always measure current draw with ALL colors on, so for RGB lights this means the light will be "white" in color. Ideally you should leave the all lights on over a period of time (an hour or so) to get a true measurement as resistance goes up (along with higher power consumption) as the wires and lights heat up.
Controller
Purpose: A controller is designed to rapidly turn off and on the power going to a light to create the impression of "dimming" - it does this usually through a process called Pulse Width Modulation.
Selection: Once you have selected your light type, then you've tested the power consumption, you can then determine which controller will be able to handle those lights. Controllers are rated in amps or watts - which are the same thing when amps is combined with a given voltage. So, if your vendor says that the controller can handle "6 amps per RGB channel" they mean that there are three individual DMX channels, each which can handle 2 amps - or a Three Channel DMX Controller. The key here is - what is the voltage, so the voltage would be, say 12 volts, so if we use Ohms law, we come up with: 12v * 2amps = 24 watts, so this controller would handle 24 watts of power for each output or 72 watts per RGB channel (3 channels.) So, if you've selected lights that you've TESTED to be 100 watts per "string" when they are lit up as white, than that single RGB output on the controller used in the prior example (72 watts) would not be sufficient to handle the load and you would either need to reduce the number of lights (less likely if the lights were planned correctly) or you would then need to divide up the load with either an additional controller or a multi-channel controller such as a 27 DMX channel / 9 RGB channel DMX controller.
Additional information: Controller terminology comes in all different forms here are some of the common terms:
Channel: Usually this refers to a single, two connection (wire, solder pad or screw terminal) output tied to a single DMX channel. So a three channel controller would have three of these outputs and would also have three corresponding DMX channels.
RGB Channel: An RGB channel is the same thing as a three channel controller - it means that with each of the three channels, red, green and blue can be controlled to make most any color.
DMX Channel: This is a single output usually, that can be adjusted from a level of 0/zero/off all the way up to 255/on.
Additional information: It doesn't make any difference if the controller is a pixel/smart controller or dumb controller - they both use power in the same way the only difference being that one can control each light individually vs all lights at the same time.
Power Wiring
Purpose: Power wiring transports the power from the power supply to the controller.
Selection: This selection is usually pretty easy and "by the numbers". Those numbers are determined by the TOTAL power consumption of ALL the LEDs attached to the controller or controllers at the other end of the power cable - it has nothing to do with your controller because if you've properly allocated the maximum number of LEDs to your controller(s), than you just add them all up. So, if you have two controllers, each with 50 watts of LEDs, you need a power cable able to handle 100 watts. So, how do you select a cable that can handle 100 watts? That depends on the distance to the controller. So, these two factors - the amount of power you need to carry and the distance between the power supply and the controller(s) - we've covered this exact topic in our blog post about RGB wiring selection - check there for additional information and wiring selection charts.
Power Supply
Purpose: To provide sufficient power at the correct voltage to the controller to power the lights.
Selection: Power supply selection is the last item to select and is pretty simple based on a few factors, such as:
Total power consumption: That same amount of power consumption that was determined in the power wiring section (the total power consumption of all the LEDs connected to the controller(s)) applies completely to the power supply. If all your LEDs require 100 watts, you'll need AT LEAST a 100 watt power supply, though usually a 10 to 20% overhead is a good idea.
Form factor: Power supplies can be purchased in many different forms - from waterproof, to water resistant to open frame. Mainly this has to do with how you intend to use the power supply. If the lights are inside, a simple shrouded power supply will be fine - no need for waterproof but if you are mounting it outside in a high humidity environment, you may be better off with a waterproof power supply. Also consider how you'll attach or mount the power supply. Also consider air flow as high wattage (250w +) power supplies often have fans and need a sufficient volume of air for cooling.
Voltage: Of course the lights you selected at the start will be a given voltage and thus this applies to the power supply. So, if you have 12v lights, you'll mostly likely need a 12v power supply.
We hope this helps you in the selection of the right wiring, power supply, controller capacity and lights for your project. Here are some other related blog articles:
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)
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?
While looking through all the great videos on YouTube showing houses outlined with RGB lights you may have wondered what is involved in getting those working on your own house. The following video provides the basic process to accomplishing this and the two different methods that are possible. Please be aware that this video only provides "generic" information as each vendors controllers and lights have specific requirements for power, protocols, lengths of run, controllers and other settings that affect the ultimate design.
We'd be happy to answer additional questions below in the comments section but please be aware that we are unable to provide vendor specific recommendations.
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.
