How to Control Christmas Lights - How to do almost anything with Christmas Displays.
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HowTo: Light Control Basics  (Mike Robinson)


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Step 0 : Introduction

Lighting control comes in many forms, from a simple on/off switch to a massive light and laser show at a concert. In this HowTo, I will go over some of the current Christmas light control methods. I will also try to explain some of the more popular control methods used on this site. For more detailed information about a specific method, see the other HowTo's. This is just an overview on setting up some lighting control, but it should help to point you in the right direction.

Step 1 : Planning Your Display

You need to decide how elaborate you want your display to be. You also need to decide how much money you want to spend. If you already have a basic Christmas light display and you're happy with it, but would like to make the lights flash to some music, you may be able to use one of the simpler light controllers. If you're like me and you find yourself constantly trying to make your display bigger and better each year, you may want to choose one of the controllers that is expandable. Keep in mind that the cost of a lighting system is more than just a controller board and some strands of lights. It’s easy to imagine an elaborate lighting display in front of your house and then jump right in – over your head. While you could make a few controller boards and have hundreds of channels at your command, you’ll find that the cost of cabling alone could be thousands of dollars. After tapping into your nest egg and spending many sleepless nights getting everything in place, you may turn on your display only to find that when the lights flash outside, they dim inside. Or worse yet that running more than 50 strands of lights trips your main breaker if the clothes dryer is on.

This brings up the next part of planning, power consumption. While it is a fact that flashing lights consume less power than ones that are constantly lit, when you light the strands all at the same time, they can put a huge load on your electrical system. In the US, a 220 volt panel is split into two busses. Each bus is 110 volts and a 220 volt circuit will use both busses. This is commonly done to power dryers, stoves, heaters, spas and air conditioners. A typical 100 count (110 volt) strand of mini bulbs draws around .33 amps of power. This means that 48 strands of lights reaches the recommended 80% continuous load for a typical 20 amp breaker. If your lights are currently plugged into outlets on the outside of your house, they are probably all tied together into a single 15 or 20 amp breaker. To run 128 strands of lights continuously, you would need 3 20 amp breakers. Add to this the fact that electrical code usually calls for a GFCI (Ground Fault Circuit Interrupt) breaker for outdoor use, so if you have the lights plugged into a porch light (for convenience) or an extension cord into the garage they are most likely unprotected. If you needed to add 3 GFCI breakers (provided your panel had the open spaces and capacity to support the load) the breakers alone could cost over $120 plus installation costs. Now we come to the capacity of your main breaker panel. Most homes have a 100-125 amp breaker panel. Older homes may have only 60-80 amp panels and they may require a $2000 panel upgrade before you can run more than a few strands of lights. A lot of newer and larger homes will have 150-200 amp panels. You won’t see more than 200 amps in a residential setting very often as that requires additional main lines run to your house from the power company. Assuming that you have a 100 amp panel with 3 available slots, an electrician can physically install the breakers. However, this doesn’t necessarily mean you can use them to full capacity.

As an example, your 100 amp 12 slot panel has 6 20 amp breakers on the left and a 50 amp double pole and a 20 amp breaker on the right. You then had 3 new 20 amp breakers added on the right. Because the two 110 volt busses alternate through the panel, this would put 2 of your new breakers on the same bus as 3 other 20 amp breakers and a 50 amp breaker. If you had an existing continuous load of 40 amps on the 50 amp breaker and 10 amps on each of the 3 existing 20 amp breakers and then tried to add another 16 amps for each of the new breakers, you would not only exceed the 20% safety margin of your 100 amp panel, you would actually exceed 100 amps and trip your main breaker shutting off all power from the panel. This means that to keep the safety margin intact, you shouldn’t run more than a total of 10 amps continuous through your 2 breakers (whether it’s 5 amps on each or 8 amps on one and 2 on the other doesn't matter.) That's only 30 strands of lights! A load approaching 30 amps on your 2 breakers would trip the main breaker. This means that you could possibly run 42 strands of lights through each of the 2 breakers, but you would be 2 amps from the max of your main breaker and it may trip if you light them all at the same time. However, you can get around this with computer control by never lighting all of your strands at once. If you want to know how much capacity you truly have, you would need to turn on the appliances and lights in your house and have the amperage they draw measured. Then you can calculate your available amperage.

This testing as well as the installation of any additional breakers and subpanels is best left to an electrician so don’t go mucking around in your electrical panel unless you know what you’re doing. A mistake could cause a fire or even death! Once you know the capacity of your existing panel or have paid the money to have some upgrades (anything from a single new breaker to multiple additional breaker panels,) you’ll know how many lights you can add and you can make the right decisions when planning the rest of your lighting system.

Step 2 : Control Methods - Standalone


Currently, you can purchase a strand of lights that has a multi-function light controller attached. You can also purchase variations such as an outlet strip version. These controllers will cycle through a series of pre-programmed lighting sequences. You can use these controllers to control your lighting show for a basic display. There are some HowTos about modifying one of the light strand controllers to control more lights, but if you overload the controller, it will die. The outlet strip method is much more flexible and the one pictured above has a remote and supports up to 30 strands of 100 lights (10 amps). In this approach, you would group your lights into channels and then the controller would cycle through the sequence, switching the channels on/off. You can take this a step farther and actually build a standalone controller, program in the sequences, and then place it in your display. For something basic such as animation, this works well. However, for timed sequences synchronized to music, this can be very complicated and is best left to those with more experience.

Pros: This system is completely plug and play if you use an off the shelf controller. If you modify a strand controller, it will take minimal time and effort.

Cons: You are limited to very few channels on most of these types of controllers and unless it is programmable you cannot change the sequences or synch them to music.

Cost Breakdown: For a simple off the shelf controller you will spend anywhere from $2-$100. The above 6 channel controller with remote was $59 at Amazon.com the last time I checked.

Step 3 : Control Methods – Simple 8/12 Channel


This is the cheapest and easiest of the computer controlled methods. This system requires a computer/laptop with a parallel port, some relays, and some extension cords or outlets. Using software you can set up a light show and it will turn the data pins of the parallel port on/off. That will cause the relays to switch which will then turn the light channels on/off. The parallel port only has 8 data pins (although it’s possible to address a few more pins for 12 channels) This means that if you want to switch 36 channels, you need 3 parallel ports in your computer. This is usually easily accomplished by installing add-in cards. Although 36 channels doesn’t sound like very much, with proper sequencing you can create a very effective display. Remember that a channel doesn’t have to be a single strand of lights and you could easily run 30 strands of lights per channel if you have 10 amp relays. That would be 108,000 lights/360 amps!

Pros – Simple, cheap, effective. You can be up and running in a matter of days and no soldering is required.

Cons – Limited number of channels. Not expandable past 3 parallel ports/36 channels.

Cost Breakdown: You will need an SSR (Solid State Relay) for each channel. These run $2-$10 each. You will also want a box to enclose the relays, a parallel cable to cut up, some wire, and either extension cords or outlets/boxes.

Step 4 : Control Methods – Kit 74


This is essentially the same as the Simple 8/12 channel controller, but can be purchased in kit form. One board gives you 8 controlled channels, each with LED indicator lights so you can easily see the status of a given channel. This board also has an extra chip to act as a buffer between the PC and the relays. This can help protect the PC in the event of a problem.

Pros: Everything is received as a package that you assemble and plug in or you can even purchase it preassembled.

Cons: The board is limited to 8 channels per parallel port, limiting you to 24 channels total.

Cost Breakdown: The price of a kit is normally $30-$35. They can be found pre-assembled for as low as $6 extra. You will still need a box to enclose the boards, a straight-through parallel (male/female), some wire, and either extension cords or outlets/boxes.



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