One of the first things a serious holiday decorator discovers, is you can spend a small fortune on extension cords to hook everything up that needs power.   Plus it is a real hassle when you need a 17 foot cord, for example, do you use a 20 or 25 foot cord, or a 6 foot plugged into a 12 foot?  What a mess keeping up with hundreds of cords, storing them, and finding the correct size, not to mention cleaning them after the season is over, prior to storage.

One solution is to make your own cords.  There are a lot of different ways to do this, this is the method I chose.
Start with a roll of SPT wire.  Opps, SPT wire comes in several different "flavors".  SPT1, SPT2, and SPT3 are the most common.  The letters SPT stand for
                                       "Stranded wire"
                                       "Parallel conductors" and
                                       "Thermoplastic insulation"

The numbers after the SPT denote the thickness of the insulation.
        1 = .030 inch
        2 = .045 inch, etc

Just think of it as table lamp cord, or "zip" cord, same thing.

Audio speaker wire also "looks" the same, but with one major important difference - voltage rating!!!!   Speaker wire and landscape wire are made to use low voltage, typically 50 volts or less.  We are using 120 volt applications, so we need wire with a voltage rating of 300 volts,  Please pay attention and be careful!!!

SPT wire also comes in various gauges denoted as AWG. Most common is 18 and 16 gauge, although 14 and 12 is also available.
The lower the gauge number, the more current it can carry.

For Holiday lighting, most use SPT1 or SPT2 in 18 or 16 gauge. 

For my purposes, I used SPT1 in 18 gauge, for the following reasons:
        1 - Most of the lights in my display are LED.  Use very                little current, so the extra expense of 16 AWG was                 not warranted.
        2 - I bundle my wires into cables covered with heat                      shrink tubing so the extra expense of the thicker                    insulation could also be avoided.
Warning:  This article deals with electricity.  If you ere not knowledgeable about this subject, seek professional assistance.  This is my own opinion and how I did it, not responsible for your actions.  No claim of electrical expertise is made on my part.
Now that you are an "expert" on SPT wire, time to grab a spool and get started.  I usually buy 1000 ft spools, since they are more economical.  Notice (from enlarged view) that this wire has white dots on one side of the pair.  This is the electrical nuteral side of the pair.  Some wire has ribs or groves on the nuteral side.  The smooth side is the hot.  This is important to know when installing the wire in the plugs and sockets.
Typically when you order your plugs and sockets, you may have a choice of brown, white or green
I usually order the white, then custom paint them to match the color of the lights that will be plugged into them.   To me, it just speeds up the process when setting up the display.  I use Krylon for Plastic spray paint.
Why are they called "Vampire" plugs?  Because they have sharp teeth that "bite" or punture the wire insulation when they are assembled.
With the cap removed, look at the end opposite the slot for wire entry.  See the pocket?  Some brands have a divider in there, in effect creating two pockets.  If yours have the divider, then make a small cut in the insulation between the two conductors, to allow each conductor to slide into its own pocket, this just helps eliminate any possibility of a short between the conductors by any stray strands of wire.
Insert the end of your wire into the slot.  Remember to observe correct polarity, you want the common side of the wire going to the wide blade or slot, and the hot side going to the narrow  blade or slot.  Then slide the cap all the way on.  The cap pushes the wire onto the teeth, piercing the insulation and holds the wire in place.
Sometimes you may want more then one socket on a wire, spaced a few inches or more from another socket.  Inline sockets for this purpose can be purchased, but rather then having an additional item to keep in inventory, I modify a standard socket to function as an inline item.  This is done by cutting away the plastic on the end with the wire pocket, resulting in a socket with a wire entry and exit slot.  Several ways to do this.  Some use diagonal cutters to nibble the excess away, while I prefer to use the Dremal tool.
Congradulations, you have just made a custom extension cord, to the exact length you need.
Most of the time, I make custom wiring harnesses.  Just a group of custom cords, grouped together to a single display item.
The wires could be zip tied together, but I prefer to enclose them in heat shrink tubing.  The advantages, in my opinion, is you have a single cable containing 3 to 8 extension cords.  Greatly speeds up display setup and the cleaning of the cords upon teardown prior to storage.  Also provides a measure of additional insulation and protection from abrasion or nicks.  The downside of this includes additional work and effort on the front end (although only is done once) and increased cost for the heat shrink tubing.  For me, being able to use SPT1 wire instead of SPT2 offsets some of the cost.

CAUTION:  Bundleling of wires does reduce the amount of current the wires can safely carry, due to heat buildup. Plan accordingly.

In my case, using LED lights, this is not a factor.

I purchase the heat shrink tubing in 100 foot rolls in the following sizes.  3/4", 1/2", 3/8", 1/4" and 1/8".  I can bundle 6, 7 or 8 wires in the 3/4" tubing.  3, 4 or 5 in the 1/2", 2 or 3 in the 3/8" tubing. 

After cutting the SPT wire to the correct lenghts, slide on the heat shrink tubing, (I usually cut the heat shink 6" to a foot shorter then my wire lengths.  Using a heat gun, shrink the tubing to result in a custom harness.
I have custom harnesses for the following applications.

6 harnesses each containing 8 lengths of SPT for the MegaTree each is 25 feet long.

4 containing  7 pairs each for the leaping arches from approx 35 to 40 feet long each

1 Harness containing 8 wires for the star on the megatree.

3 wires for the flying angel.

6 harnesses containing 6 wires for the giant bulbs, ranging from 45 feet to 65 feet in length.
I also use SPT wire and vampire sockets for my LOR contollers outputs
Photos Soon
Photos Soon
Photos Soon
Photos Soon
More info to be added soon
This page was last updated: January 17, 2010
Where to purchase supplies.  Links to vendors