HOW TO USE LED CHRISTMAS LIGHTS AND OTHER FACTS ON CHRISTMAS LIGHTS Too many times, the devices you bought for the old kind (incandescent) of Christmas lights do not work with the new LED Christmas lights. But there are tricks you can use to get these devices to work with many kinds of strings of the new lights. Here are the questions and answers needed to get the desired results with LEDs and with other lights:

• What are light emitting diodes?

  A Light-Emitting Diode (LED) is a device that emits light when current passes through it in only one direction. Current does not flow through it in the other direction.

• What is a string of LED Christmas lights?

  DANGER

  DO NOT BUY OR USE THESE BULBS

  

  These imported candelabra-base LED bulbs have enlarged metal ferrules (indicated in diagram) that are connected to the screw shell. An unsuspecting person touching or changing this bulb can contact this live metal part.

    ELECTRICAL SHOCK HAZARD!  

  DO NOT USE THIS KIND OF BULB in Christmas light strings or in any socket where the ferrule is exposed. An unpolarized plug on the light string, Christmas lights connected in series, or an open neutral wire in a light fixture can leave the ferrule connected to the live side of the power line.

  A string of LED Christmas lights is a set of LEDs connected in series with a current limiting device to keep the current to a safe level. There are several kinds of LED light strings:

  • A single series of LED lights. It passes current in only one direction in the alternating current cycle.
  • Two series of LED lights wired so they pass current in opposite directions in the AC cycle.
  • One or more series of LED lights fed by a full-wave rectifier.
  • One or more series of LED lights fed by a voltage doubler circuit.
  • One or more series of LED lights fed by a sophisticated (e.g. switching) power supply.
  • One or more series of LED lights fed by a light controller powered by any kind of power supply.
  • A parallel Christmas light string intended for incandescent bulbs with individual 120 volt LED bulbs installed in the sockets.

  Each one behaves similarly when supplied with alternating current, but behaves very differently when fed power from a special device.

• What is a string of incandescent Christmas lights?

  A string of incandescent Christmas lights is a set of incandescent lamps wired in either series or parallel. They draw current in both directions of the alternating current supplied by the power company.

• Are there other kinds of strings of Christmas lights?

  Yes. The following kinds of Christmas lights have also been sold.

  • Strings of neon (gas discharge) lamps are available. They usually have glowing shapes inside large globes.
  • They used to make fluorescent Christmas lights in the 1940s.
  • Some electroluminescent strings were made briefly in the 1960s.
• How do incandescent Christmas lights blink on and off?

  Five methods are used to make the lights blink on and off.

  • A blinking device can be added to an entire string of lights in parallel. It makes the entire string blink in unison.
  • Individual twinkle bulbs (using thermostatic blinkers) can be added to a parallel string for individually twinkling lights.
  • A single individual twinkle bulb (using a thermostatic blinker) inserted into a series string will make the entire string blink in unison.
  • Special Individual twinkle bulbs (using thermostatic shorting blinkers) can be designed into a series string for individually twinkling lights. But fewer than a quarter of the lamps can have this device or the other lamps will burn out.
  • A control box built into the string or connected to it changes the brightness of parts of the string.
• How do LED Christmas lights blink on and off?

  Three methods are used to make the lights blink on and off.

  • An electronic circuit in the bulb holder switches the current through either the bulb or a loading device in the holder. It can also dim the bulb.
  • A control box controls the brightness of one or more strings.
  • A control box sends signals to individual lamp units telling them what to do.
• When is special fusing needed to protect electrical devices?

  Special fusing is needed when substitutions are made in what a device powers:

  • When an LED bulb is substituted for an incandescent bulb, a fuse should be inserted in the circuit if the bulb is supplied by a transformer.
  • When an LED bulb is substituted for an incandescent bulb, a fuse should be inserted in the circuit if the bulb is supplied by a special device.
  • Failure of a screw shell (or two-pin) LED can damage a dimming or timing device. A fuse should be added.
  • Mini light strings have fuses in the power plugs. These fuses will be enough
• What are "special devices"?

  Special devices designed to operate incandescent Christmas lights in any of the following ways:

  • Making the lights chase in sequence
  • Creating interesting patterns in lights (e.g. the GE Gala set)
  • Making lights dance to music
  • Mixing colors using red, green, and blue lights
  • Mixing colors to fade around all possible hues mixed with red, green, and blue lights
  • Mixing colors to fade around all possible colors mixed with red, green, and blue lights
  • Making lights slowly fade up and down
  • Making lights shimmer or behave like candle flames
  • Making light patterns in a grid (e.g. as on a disco floor)
  • Making light patterns move up and down or around and around a tree
  • A master control system that lights an entire house with many patterns
  • A MIDI (Musical Instrument Digital Interface) controlled system of lights changing to music
  • Converting power from a car to operate the lights
  • Doing more than one of these functions
• What are the ways that LED light strings fail to work with special devices?

  There are several reasons the LED strings fail to work with special Christmas display devices

  • The lights do not pass both directions of alternating current, causing the special device to stop passing power or to pass it wrongly.
  • The special device rectifies the alternating current to direct current, causing part of the LED string to fail to light, or causing too much current to pass through the LEDs (designed to have a rest during part of the AC cycle), burning them out.
  • The special device rectifies the alternating current to direct current, so any switching power supply in the string will not run. The string will not light.
  • The string does not draw enough current to make a normal TRIAC dimmer work.
  • The string has a low power factor, causing phase errors in the special device. This can make the lights stick on, blink on and off, stay either full on or full off, or fail to light.
• How many kinds (electrical) of strings of incandescent Christmas lights exist?
  

  There are 3 different kinds of incandescent strings:

  • S: A number of low voltage lamps connected in series. The voltages of the lamps add to 120 volts. If one lamp fails, all of them go out.
  • P: A number of 120 volt lamps are connected in parallel. If one lamp fails, the others remain lit.
  • C: A controller operates one or more sets of low voltage lamps connected in series. If one lamp fails, all of them go out.

  Note that different styles or colors of bulbs can be substituted with incandescent lamps as long as the lamps are the same voltage as the originals and they fit the sockets.

  Note that led replacements for 120 V parallel incandescent lamps can be substituted for other 120 V lamps in a parallel incandescent string if they fit the sockets.

  Note that many miniature series sets have shorting devices so that only the failed lamp goes out. But this puts more voltage on the other bulbs so they burn out faster if the failed bulbs are not changed out.

• How many kinds (electrical) of strings of LED Christmas lights exist?
  

  There are at least 9 different kinds of LED strings:

  • H1: A half-wave string that passes only one direction of the AC cycle.
  • H2: A dual half-wave string that passes one direction of the AC cycle through half of the string and the other direction of the AC cycle through the other half of the string.
  • F1: The string has a full-wave rectifier that sends both directions of the AC cycle through the same LEDS in the same direction. This is the most compatible LED string for special devices.
  • F2: The string has a full-wave rectifier with a filter capacitor that sends both directions of the AC cycle through the same LEDS in the same direction. This is the second most compatible LED string for special devices.
  • B1: The string has a bidirectional LED in each bulb. It passes current in both directions of the AC cycle through the LEDS.
  • D1: The string has a half-wave voltage doubler that uses both directions of the AC cycle to double the voltage through the LEDS. This requires a full-wave AC power source.
  • S1: The string has a switching power supply to power the LEDs (It does not flicker. But most special devices cannot power it).
  • C1: The string has its own special controller that could have any kind of power supply. But it has its own controlling functions that make the lights do things.
  • M1: Each lamp in the string has its own special controller that makes the light do things. These must not be connected to other controllers except on-off timers.

  Note that any of these different kinds can have several series sets of LEDS in parallel (as seen in the F1 and F2 diagrams) or just a single series (as seen in H1). The number of sets in parallel does not change the kind of circuit.

  Note that different styles or colors of bulbs can NOT be substituted with LED lamps, except that led replacements for parallel incandescent lamps can be substituted for other lamps in a parallel incandescent string.

• What happens if the light string is incompatible with the special device?

  Look for any unexpected behavior:

  • The string fails to light.
  • A fuse blows
  • Half of the string fails to light.
  • The lights flash on and off rapidly (when they are not supposed to).
  • The lights are either fully on or are off (in a device that fades brightness).
  • The light string (or an individual light) burns out.
  • Part of the special device burns out.
  • The special device has a full-wave rectified output which overloads half-wave LED strings (they are too bright).
• What can be done to make LED lights work with special devices?

  In most of the cases, making the load look like incandescent lamps will make the device work with the LED lamps.

  Note that this does NOT work when the LED string has a sophisticated power supply.

  A Converter-Driver works in almost all cases, but it is more expensive.

• What can make LEDs look to the special device like incandescent lamps?
  

  Add a small incandescent load to the circuit:

  Make a load using two incandescent lamp sockets wired in series and spliced into a short extension cord connected between the special device and the LED light strings. The page author used candelabra-base sockets mounted on an electrical junction box.

  Be sure that all connections are well insulated, with heat-shrink tubing, electrical tape, wire nuts, or liquid tape.

  Use TYPE A for normal dimmers.

  Use TYPE B if the device puts out pulsating DC (see below). May not work with all strings.

  Use TYPE C or TYPE D if the special device puts out full-wave rectified DC, but the string is half-wave.
  - If this is true, the string will be brighter on the special device than it is in a standard power socket.
  - The TYPE C load limits string current.
  - The TYPE D load limits string voltage.
  - The TYPE C load also needs a calculation for x in the TYPE A Load.

  Use TYPE E for strings that draw too much current and burn out too quick.

  Use TYPE F for strings that draw too much current and burn out too quick. It uses 4 identical bulbs.
  - In use with 5W bulbs to cut voltage to 107V.

  Use a fuse in either TYPE A or TYPE B that lets the string or lamp work normally, but will blow if the string or lamp shorts out.
  - No fuse is needed for TYPE C, D, or E.

  Use the following tables to determine the minimum size of the incandescent bulbs needed to use the LED strings.

  CALCULATING VALUES
  LOADED CORD TYPE A				LOADED CORD TYPE B						LOADED CORD TYPE C
  NEED LOAD = x/2				FIND CAPACITOR y						FIND LOAD z
  One Bulb x (W)	Two Bulbs Each (W)	Hot Bulb Each (Ω)		Cap y (μF)	Xc @ 60 Hz (Ω)	LEDs (mA)	Est Load (Ω)	Std Bulb Load (W)		LEDs (mA)	Hot Bulb Res (Ω)	Bulb volt drop (V)	Std Bulb z (W)
  4	2	7200		1	2653	4	3316	4		20	2880	57.6	5
  5	2.5	5760		2	1326	8	1658	10		40	1440	57.6	10
  7	3.5	4114		3.3	804	13	1005	15		60	960	57.6	15
  10	5	2880		5	531	20	663	20		*	*	*	*
  12	6	2400		10	265	40	332	50		*	*	*	*
  15	7.5	1920		20	133	80	*	*		*	*	*	*
  20	10	1440		33	80	132	*	*		*	*	*	*
  25	12.5	1152		50	53	200	*	*		*	*	*	*
  30	15	960		100	27	400	*	*		*	*	*	*
  40	20	720		200	13	799	*	*		*	*	*	*
  60	30	480		330	8	1319	*	*		*	*	*	*

  * Beyond the scope of LED Christmas Strings - Use a method other than Loaded Cord Type B or C.

  CALCULATING VALUES
  LOADED CORD TYPES A, D, AND E													LOADED CORD TYPE D WITH STRING
  Lamp properties							Series properties						ALL	Lower series t&t value of t
  Rate 120V (W)	Bulbs t and u			Bulb t	Bulb u		Rate 120V (W)	2 Bulb Series Values					Upper Rated (W)	t to set current
  	120V (mA)	hot (Ω)	cold (Ω)	60V (mA)	50V (mA)			120V (W)	120V (mA)	hot (Ω)	cold (Ω)			0 mA	10 mA	20 mA	30 mA	40 mA
  4	33.3	3600	450	16.7	13.9		4	2	16.7	7200	900		5	4	†	†	†	†
  5	41.6	2880	360	20.8	17.4		5	2.5	20.8	5760	720		6	5	†	†	†	†
  6	50.0	2400	300	25.0	20.8		6	3	25.0	4800	600		7.5	6	4	†	†	†
  7.5	62.5	1920	240	31.3	26.0		7.5	3.75	31.3	3840	435		10	7.5	5	4	†	†
  10	83.3	1440	144	41.7	34.7		10	5	41.7	2880	360		12	10	7.5	5	4	†
  12	100	1200	180	50.0	41.7		12	6	50.0	2400	300		15	12	10	7.5	5	4
  15	125	960	120	62.5	52.1		15	7.5	62.5	1920	240		20	15&20	15	12	10	7.5
  20	167	720	90	83.3	69.4		20	10	83.3	1440	180		25	20	15&20	15	12	10
  25	208	576	72	104	86.8		25	12.5	104	1152	144		30	25	20&25	20	15&20	15
  30	250	480	60	125	104		30	15	125	960	120		40	30&40	30	30	25&30	25
  40	333	360	45	167	139		40	20	167	720	90		*	*	*	*	*	*

  * Beyond the scope of LED Christmas Strings - Use a method other than Loaded Cord Type D.
  & Between standard lamp sizes - use one of each in the series.
  † Below the scope of LED Christmas Strings - Use a method other than Loaded Cord Type D.

  Calculating for load TYPE D

  • The series forms a voltage divider when combined with the current drawn by the light string(s).
  • The upper lamp u wattage is adjusted so the voltage across it is 50 volts.
  • The lower lamp t&t series and the string(s) should have 120 volts across them.
  • If a single-direction half-wave string is used, calculate for the direction of current flow in the string.
  • If current flows in opposite directions are unequal, calculate for the direction with the higher current.

  If the special device has a minimum wattage rating, use that in the left column of the tables.

  CAUTION: Do not exceed the Device Max power capability of the special device.

  If the special device does not specify a minimum wattage, use trial and error, starting with the largest size in the table that does not exceed the output capabilities and working down until the special device misbehaves. Then go up at least 20 percent from the value that made it fail, to make sure the special device does not intermittently fail.

  Because the two lamps are in series, they should rarely burn out. But keep some spares, because they may ban all incandescent lamps.

  The load lamps do not need to be part of the display. They can be hidden in any out-of-the-way place. But make sure they have ventilation air and do not touch other materials.

  This TYPE A load will be referred to as a loaded cord.

  An output with this TYPE A load device connected to it will be referred to as a loaded output.

  The capacitor in the TYPE B load must be non-polarized.

  Experiment with bulb z wattage in the TYPE C and TYPE D loads to make string brightness the same as the string plugged into a standard power socket. Bulb z might not reach full hot resistance.

• What devices has this loaded cord trick worked for?

  These loaded outputs have worked for the page author for the following:

  • An old-style thermal flasher
  • A chase-light sequencer
  • A color-fader sequencer
  • Two different dance-to-the-music color organs
  • A candle-flame flicker simulator
  • A lamp dimmer
  • A GE Gala set with the light strings cut off* and the ends of the extension cords with the loads spliced into the cut ends from the controller,
    - The output is full-wave rectified DC and requires Loaded Cord C.
    - Note that each socket is fused and marked as being for only LED Christmas lights.
    * The incandescent light strings were already damaged. The page author wanted to keep the functionality of the set, but use LED lights.
• What if none of the string lights when connected to a loaded output, even though the load lamps light?
  • If the string does not work when plugged directly into a wall outlet, the string is bad or the fuse is blown.
  • If the string works when directly plugged into an outlet, but not on the loaded output of the special device, a DC string may be plugged in backwards. Turn the plug of the string over.
  • If the string still does not work on the loaded output, but works in a wall socket, it has a switching power supply. It will not work with the special device.
  • If the plug is polarized and will not go in the other way, try turning the plug over at the special device end of the loaded cord.
  • If neither plug can be turned over, see the question about "The DC string has the wrong polarity" below.
• What if the lights of the string are brighter on the special device than they are when plugged into a standard power socket?
  • Do not use them this way or their lives will be shortened.
  • The special device outputs full-wave rectified DC. The LED string is half-wave.
  • Use Loaded Cord D to fix the problem.
• What if the lights of the string are brighter than they should be and burn out quickly when plugged into a standard power socket?
  • Do not use them this way or their lives will be shortened.
  • Possibly the string is mismanufactured or is made for the 100V power of northern Japan.
  • Possibly the string has a capacitor current load instead of a resistor. Surges destroy LEDs.
  • Use Loaded Cord E to fix the problem.
    • If the string is made for northern Japan, the series load E must absorb 20 volts at probably 20 mA. This needs a resistive load of 1000Ω cold.

      This load E requires a 4W and a 3W lamp in series.

    • If the string passes too much current or has a capacitive load the series load E must absorb 10 volts at probably 20 mA. This needs a resistive load of 500Ω cold.

      This load E requires two 7W lamps in series.

• What does "turn the plug over" mean?

  Pull the plug out of the socket, turn it half a turn, and plug it back in, so the two prongs are inserted into each other's slots.

  Note that this does not work if the plugs are polarized or a three-prong plug is used.

• What does it mean that the plugs are polarized?
  

  The neutral blade of the plug is wider than the live blade. This is made so the neutral blade is always plugged into the neutral slot in the outlet.

  The plug will not fit into the socket the other way.

  Three-prong plugs with the safety ground pin are also polarized.

  This was done so that the screw shell of an Edison-base light bulb socket is always connected to the neutral.

  This prevents someone from accidentally contacting a live screw shell of a light bulb when changing bulbs. It is a safety device that should normally not be defeated.

  In the case of LED Christmas lights, there is no agreement between manufacturers of the polarity of a string that works on only half of the AC cycle (or on DC).

  • Many strings do not have polarized plugs.
  • Some string manufacturers do not standardize the polarization of their strings.
  • Often the polarization of the plug does not match the DC polarization of the device feeding the light string.
  • Some strings pass current to half of the lights on each half of the AC cycle.

  The surgeries on light strings listed below change the polarity of part or all of the string without changing the polarity of the outlet at the end of the string.

• What if only half of the string lights up when it is plugged in to the loaded output?

  If this occurs, the entire string needs AC, but the special device output is DC. See below.

• What needs to be done to fix a case where only half of the string lights?

  There are several possibilities:

  • Replace LED string with one that works on DC (e.g. has full-wave rectification).
  • Replace the special device with one that provides an AC output.
  • Use the TYPE B loaded cord (see above). Note that this does not work with some strings.
  • Do surgery on the LED light string to make it work on DC. See next question.
  • After the surgery, the TYPE C loaded cord is needed is the string is too bright.
  • Build a relay device or a TRIAC Converter-Driver that converts one kind of output into the other.
• How can I build a Converter-Driver?
  

  Use the wiring diagram at right:

  • The plug on the left goes into any special device.
  • The plug on the right supplies power to the strings or lamps.
  • The TYPE A load and full-wave rectifier should work with any special device.
  • Build the TYPE A load and choose bulbs to fit your special device.
  • Choose the triac to be able to drive the load you have with capacity to spare.
  • This circuit can be built to drive loads much larger than the special devices can drive.
  • This circuit provides electrical isolation between the special device and the load circuit.
• What surgery needs to be done to a light string to fix a case where only half of the string lights?
  

  To do the surgery on the string:

  1. First check to see if the light string can be so modified. If any of the following are true, the string cannot be easily modified. If this is so, a different string must be used:
     • If the string has more than 3 wires twisted together at any point, the series strings are interleaved. This is not easy to modify, and is not covered here.
     • Strings with built-in controllers must not be modified. But they usually already use DC.
     • If a string has more than 35 lights, but has no place with only two wires twisted together, the string will be hard to modify. This is not covered here.
     • If the string has more than 80 lights, there are probably more than two series sections in the string. Such strings are harder to modify, and are not covered here.
  2. Connect the string to the special device DC output and note whether the half of the string closest to the plug or the half farthest from the plug lights. Remember this for later.

     Note that, if the string contains more than 80 lights, there may be 3 or 4 sections of lights. If so there may be multiple portions of the string lighted or dark. This can be modified, but it is not covered here.

  3. Disconnect all power from the string.
  4. Find the place in the middle where only 2 wires (instead of 3) twisted together go between lamps at point A.
  5. Use a permanent marker to mark the length of only one wire between the lamps at point A.
  6. Cut both wires at this point, and strip the ends 1/4 inch.
  7. If heat-shrink tubing is used, slip half-inch pieces onto both wires going to the same half of the string BEFORE connecting the wires.
  8. Trade the wires of half of the string, so the marked wire on one half goes to the unmarked wire on the other half.
  9. Connect the wires with solder or wire nuts.
  10. If using solder, apply the insulation method used (heat-shrink tubing, electrical tape, or liquid tape).
  11. IF the portion of the string closest to the plug lit up

      THEN Repeat steps 3 thru 10 at point B. Do not modify point C

      ELSE IF the portion of the string farthest from the plug lit up

      THEN Repeat steps 3 thru 10 at point C. Do not modify point B

  12. Test the string on the DC loaded output. If no lights come on, turn the plug over.

  Explanation: Switch wires at each end of the portion of the lights that were dark.

• The DC string has the wrong polarity. What needs to be done to fix a case where the string polarity is wrong, compared to the DC output of the special device?

  This is a case where the polarity is wrong, but a polarized plug won't allow the correct polarity.

  • If the loaded cord was attached to the DC output of the special device (e.g. the GE Gala), by the user, switch the two wires where the cord connects to the device.
  • If the socket is hard-wired to the special device, apply the above surgery to only points B and C on the light string (see above). Point A does not exist in this kind of string. This reverses the polarity of the entire string.
• Can a tool be built to test special device outputs and light strings for load and polarity?
  

  Yes. The tester can test all of the following:

  • The special device output
  • The LED string of Christmas lights
  • Connection between the special device and the LED string of Christmas lights

  Features of the Tester:

  • The grounded (3-prong) power plug PS (orange) to be plugged into a grounded outlet.
  • A grounded (3-prong) socket SD (white) for powering the special device.
  • An ungrounded (2-prong) plug SD (white) for the output of the special device. The plug is ungrounded so it will fit either a grounded or an ungrounded output socket. If the special device is not used, the SD Plug and the SD socket must be connected together.
  • A grounded (3-prong) socket LS (orange) for the light string. The grounding comes from the PS power plug.
  • Switches for DC simulation (A and B), loading (C), and AC restoration (D and E).
  • Green LED lamps for observing the AC and DC output characteristics of the special device.
  • Red LED lamps for observing the AC and DC characteristics of the power feeding the light string.

  Information about the tester circuit:

  • The page about this circuit is here.
  • The circuit and operating instructions are here.
  • A schematic diagram is at right.
• How does a single-color LED work?

  An LED is a semiconductor diode.

  All semiconductor diodes emit light when they conduct electricity in the forward direction. But most of them emit light in the infrared band, where it can't be seen. Also, to keep stray light from affecting the diode, the diode is usually encased in black plastic or epoxy.

  Light emitting diodes are tuned by the kinds of semiconductors and impurities used, so each emits a selected color of light. The band of colors emitted by a single LED is usually narrow enough to be perceived as a single color.

• How many different colors of LEDs are made?

  More than are available for Christmas lights.

  Among those colors available are:

  Deep Red

  Red

  Orange Red

  Orange

  Amber

  Yellow

  Yellow Green

  True Green

  Aqua

  Cyan

  Powder Blue

  Deep Blue

  Violet

  Purple

  Magenta

• How do white LEDs work??

  Most white LEDs are made with a blue LED element and a phosphor that emits yellow light when illuminated by the blue LED. The blue LED usually emits blue and violet light, while the yellow phosphor emits orange, yellow, and green light, along with some red light.

  Note that most white LEDs have three gaps in their spectra. These gaps emit very little deep red, cyan, or deep violet light. But, unless the light strings are being used to illuminate objects with unusual color pigments, this should not be noticed.

  Some white LEDs have red, green, and blue LED elements. These colors mix to white to the eye. But this LED has, in addition to the spectral gaps above, an additional gap in the yellow part of the spectrum. These are used where the color white must be seen, but the LED is not needed to illuminate something else (e.g. a pedestrian WALK indication).

• How many different colors of white LEDs are made?

  More than are available for Christmas lights.

  Among those colors available are:

  Pink	Warm White	Soft White	Bright White	Cool White	Sunlight	Sky White	Daylight	Lunar White

• How do LEDs that change color work??

  There are usually two or three LED elements in the same LED package, or there are two or three LEDs in the same translucent cover. The colors are usually the primary colors of light: red, green, and blue. These colors can be mixed to produce any desired color. A controller selects the color.

• Why do the white LEDs fade over time?

  If the lights are left on all the time, or are left where they are exposed to sunlight, the yellow phosphor is degraded. It emits less light the longer it is exposed to strong light. So the light of the white LED slowly gets dimmer and bluer.

  The white made using red, green, and blue LED elements does not fade in this way.

• Why do LEDs fail?

  Failures are usually caused by power surges, static electricity, lightning, too much current, or a rare random strike by high-energy radiation (e.g. cosmic rays). If too many LEDs have failed, the whole string can suddenly fail.

• Do some LEDs fail more often than others?

  The page author has had many more failures of blue and white LEDs than he has had in other colors. Green, yellow, and orange LEDs seem to fail much less often. And the page author has never had a red LED in Christmas lights fail.

  It seems that the higher the forward voltage of the LED is, the higher the failure rate is. Any power surge would be more likely to be absorbed by an LED with a higher forward voltage.

  Update 2017: The page author has a string of icicle lights with independent RGB color in each icicle. One of the blue lights has failed completely, and 4 of the others have flickering blues. Not one of the green or red LEDs has failed.

• Why aren't LED light strings with all yellow lights or all green lights available?

  Mass marketing seems to have a stupid aversion to having more than 5 varieties of a product. The LED Christmas light industry originally gave us red, yellow, green, blue, and cool white strings. Now they give us red, warm white, blue, multicolored, and one other type (usually cool white, green, purple, or blue and white multicolored). Blame business schools for this idiotic kind of thinking.

  Update: Green is missing for a different faulty marketing practice: They make stores buy the same number of each kind of string. The green ones sell out first, and the store can't order more green without ordering more of all of the other types. Buy early for green.

  If you look before Halloween, you can often find orange, green, and purple strings. If these are needed, buy them then.

  It is time to get rid of this idea that there should be only a certain number of variations in products on the shelves. Write the companies and complain. Offering only 5 color choices is like telling an artist that he must choose among only 5 colors of paint.

  It is time to get rid of the idea that Christmas lights must be sold wholesale in lots containing the same number of each kind of string. Write the companies and complain.

  There are now LEDs in many different colors, including red, orange, yellow, green, cyan, blue, violet, purple, magenta, warm white, and cool white. There are also multicolor strings, usually with only 5 colors (again a 5). We should be able to buy whichever kinds we want, because different people have different ideas for Christmas displays.

  The worst set of colors I ever saw on a light string was the set offered on the old C9 multicolor strings: red, orange, green, blue, and white. Ugly!

  DEAR CHRISTMAS LIGHT MANUFACTURERS - PLEASE LEARN THIS:

  People who buy lights to make Christmas displays are not just buying what they can get to hang on a tree. They are creating art, and want the choice of a wide palette of colors to mix, match, and arrange on a tree or anywhere else. But, unlike GE (who is making all of these colors in incandescent strings), the LED manufacturers and ornament makers want to stick to as few colors as they can get away with.

  The page author would like to be able to buy single-color light strings, replacement lamps, and ornaments in at least the six new primary colors (not the old ones). But nobody seems to make all six of the colors:

  Magenta	Red	Yellow	Green	Cyan	Blue

  A string with all six of the new primaries would also be very desirable to the page author. He would also like to be able to buy single-color strings, replacement lamps, and ornaments in these other colors: orange, lime, violet, purple, pink, baby blue, warm white, cool white, and daylight.

  The page author would also like to have an 8-color string with the six new primaries, orange, and violet, and an 8-color string with the six new primaries, warm white, and daylight. But if the lights were actually interchangeable, he could build these strings.

• Can the LED lamps in multicolor strings be traded from string to string to make single-color strings?

  No. Not with the technology they sell today.

  (An exception to this is the 120-volt LED bulb sold for replacing the standard C7 incandescent bulbs in standard parallel Christmas light strings. These can be arranged any way the buyer wants them.)

  Usually a series string has 35 LEDs, with a resistor to drop the remaining voltage to provide a current of about 20 milliamperes (mA). Remember that LEDs use the peak voltage of 170 V, not the effective voltage of 120 V.

  The problem is that the different colors of LEDs use different voltages, so the different strings have different resistors. The values here are typical, but not always used:

  • Warm colors (red, orange, and yellow) have lower voltages (around 2 volts).
    The 35 LEDs drop about 70 volts, leaving the resistor to drop the remaining 100 V.
    To get 20 mA at 100 V, a 5000 ohm 2 watt resistor is needed.
  • Cool colors (green and blue) and white have higher voltages (around 3.5 volts).
    The 35 LEDs drop about 122.5 volts, leaving the resistor to drop the remaining 47.5 V.
    To get 20 mA at 47.5 V, a 2400 ohm 1 watt resistor is needed.
  • Mixed colors (red, yellow, green, and blue) have equal numbers of both voltages.
    The 35 LEDs drop about 97 volts, leaving the resistor to drop the remaining 73 V.
    To get 20 mA at 73 V, a 3600 ohm 2 watt resistor is needed.

  The series resistor in each string is sized according to the number of lower voltage LEDs and higher voltage LEDs expected to be in the string. If you buy several multicolor strings and trade LEDs between the strings, the following problems happen:

  • Red, orange, and yellow strings made this way draw excess current, burning out LEDs.
    The 100 volts on the 3600 ohm resistor draws 2.8 mA (too much).
  • Green, blue, and white strings made this way have too little current to fully light.
    The 47.5 Volts on the 3600 ohm resistor draws only 13 mA, making the string dim.

  Unless you are an expert at modifying electronic circuits to put in different resistors, it is best not to move LEDs from string to string.

  DEAR CHRISTMAS LIGHT MANUFACTURERS - PLEASE FIX THIS:

  Manufacturers should put full-wave rectified constant-current power sources in each series string. Then the colors can be mixed up without causing damage or trouble. All three of the above cases would draw the same 20 mA. This would all have the advantage that all of the strings would use the same parts, eliminating special multiple inventories.

  There has been a tradition in my family of moving the bulbs around so there was not a concentration of one color in a given area. It worked with old C6 series sets, old C7 and C9 parallel sets, and series miniature incandescent lamps. But it will not work with LEDs. This is wrong.

  The page author would like to be able to buy a string of LED lights and extra bulbs in many different colors. Then he could populate it with many different colors to produce the wanted display effect.

  The page author would prefer lamps in parallel over lamps in series, since any lamp can be placed in any socket and lamps can be swapped between strings.

  The page author has several special devices and lamp controllers designed for incandescent lamps and he wants to be able to keep using them. While they do not work with all installed lamps being LEDs, they do work if an incandescent load is there in addition to the LEDs. See the loaded cord above. So incandescent lamps are still needed.

  Many people have sentimental attachment to displays they grew up with or displays their relatives had. They want to continue using them. They have known these displays all of their lives and need to be able to buy replacement bulbs (either incandescent or LED) for them:

   
  E
  X
  A
  M
  P
  L
  E
  S

  That creche is over 8 feet wide.

• Is there any hope for having strings of Christmas lights where the user can put any color where he wants it in the string?

  Yes. They are now making screw-in LED replacements for standard C7 and C9 incandescent bulbs. The person who wants to arrange a string can buy a string of C7 or C9 incandescent bulbs and these 120 V LED replacements.

  Replacement 120 V LED lamps are currently available from Christmas Valley in red, yellow, green, blue, and warm white.

  The problem is that vendors would rather sell miniature sets than large replacement bulbs.

  DEAR CHRISTMAS LIGHT MANUFACTURERS - THIS IS THE RIGHT IDEA:

  Here are the products we want to buy:

  • Strings of standard screw-shell C7 or C9 lamps with 120 V LED lamps all the same color
  • Strings of standard screw-shell C7 or C9 lamps with assorted 120 V LED lamp colors
  • Boxes of replacement 120 V LED bulbs in many different colors
  • A wide palette of colors to mix, match, and arrange on a tree or anywhere else
  • Single-color light strings and replacement lamps in at least the six new primary colors (not the old ones):
    - The new primaries are:

    Magenta	Red	Yellow	Green	Cyan	Blue

  • Strings with all six of the new primaries included.
  • Strings and replacement lamps in these other colors:

    orange	amber	lime	baby blue	violet	purple	pink	warm white	cool white	daylight

  • 8-color strings with the six new primaries, orange, and violet

    Magenta	Red	Orange	Yellow	Green	Cyan	Blue	Violet

  • Of course, the colors do not have to be in the order shown. These string orders can be used.
  • 8-color strings with the six new primaries, warm white, and daylight.

    Magenta	Red	Yellow	Green	Cyan	Blue	warm white	daylight

  • A wide palette of ornament colors to mix, match, and arrange on a tree or anywhere else
  • No more "fad colors" that appear for a year or two and then disappear. Colors must remain available so people can add to existing displays.
  • No wholesale package deals with equal amounts of several products. Vendors must be able to order lots of single products, not package deals.

  THIS IS WHAT WE WANT!

• How can a few colors of lights on the tree make many more colors in the room?

  A color fader sequencer is used with Christmas lights on the tree in the primary colors of light. The lights mix to make the other colors. Note that some sequencers can make all colors (including dark), while others cycle through only the pure colors (see table below at the left).

• This didn't work using red, yellow, and blue strings. Why didn't it work?

  The primary colors of light are red, green, and blue.

  Red, yellow, and blue were once the paint primaries, but they never worked for light. They work for oil paints, but not very well for other kinds of pigments. The current more accurate paint primaries are magenta, yellow, and cyan.

  What happens if the wrong primaries are used?

  Used For Light			Used For Pigments			Used With Oil Paint
  Old Primaries	Light Primaries	Pigment Primaries	Old Primaries	Light Primaries	Pigment Primaries	Old Primaries	Light Primaries	Pigment Primaries

  1. If the wrong primaries are used, the wrong colors appear.
  2. Using the wrong primaries gives a smaller gamut of colors.
  3. Notice the complete lack of greens with the old primaries.
  4. Colors are pastel with the wrong primaries for light.
  5. Colors are dark with the wrong primaries for pigment.
  6. Color-sensitive pigments in the eye dictate the primaries to use.
  7. The correct choice for Christmas lights is underlined.

  See Teach the correct primary colors for more about this.

  The colors red, green, and blue are mixed in the ways shown in the table below at the left:

  COLORS MIXED FROM VARIABLE RED, GREEN, AND BLUE Color Wanted Color Strength   Red   Green  Blue    Red 100% 0% 0%   Orange 100% 50% 0%   Amber 100% 66% 0%   Yellow 100% 100% 0%   Leaf 50% 100% 0%   Green 0% 100% 0%   Aqua 0% 100% 50%   Cyan 0% 100% 100%   Azure 0% 50% 100%   Blue 0% 0% 100%   Violet 50% 0% 100%   Purple 66% 0% 100%   Magenta 100% 0% 100%   Cerise 100% 0% 50%   Dim White 50% 50% 50%   White 100% 100% 100%   Pink 100% 50% 50%   Peach 100% 67% 33%   Straw 100% 100% 50%   Pea 66% 100% 33%   Baby Blue 33% 50% 100%   Powder 33% 50% 100%   Cornflower 33% 50% 100%   Lilac 67% 33% 100%   Lavender 80% 33% 100%   Rose 100% 33% 80%   Black (dark) 0% 0% 0%	On the left are the relative strengths needed to produce the desired colors (among many others) from variable brightness displays. The question above covers this color set. Many more colors are possible. On the right are the only colors produced with two sets of red blinking lights, two sets of green blinking lights, and two sets of blue blinking lights. The question below the tables covers this color set. "Events out of 64" shows the relative frequency of each color, given that each of the 6 lamps has an equal chance of being on or off. It is the expected number of times the color would appear when 64 random samples of color are taken.	COLORS MIXED FROM BLINKING RED, GREEN, AND BLUE Color Wanted Lamps On Events out of 64   Red   Green  Blue    Dim Red 1 0 0 2   Red 2 0 0 1   Orange 2 1 0 2   Dim Yellow 1 1 0 4   Yellow 2 2 0 1   Leaf 2 1 0 2   Dim Green 0 1 0 2   Green 0 2 0 1   Aqua 0 2 1 2   Dim Cyan 0 1 1 4   Cyan 0 2 2 1   Azure 0 1 2 2   Dim Blue 0 0 1 2   Blue 0 0 2 1   Violet 1 0 2 2   Dim Magenta 1 0 1 4   Magenta 2 0 2 1   Cerise 2 0 1 2   Dim White 1 1 1 8   White 2 2 2 1   Pink 2 1 1 4   Straw 2 2 1 2   Pale Green 1 2 1 4   Baby Blue 1 2 2 2   Cornflower 1 1 2 4   Lavender 2 1 2 2   Black (dark) 0 0 0 1
  Below are the only colors produced with two sets of red blinking lights, two sets of green blinking lights, and two sets of blue blinking lights, where each color has a blinker with two strings and another blinker with one string. Each of the colors in the table below have equal probabilities of occurring if each of the 6 blinkers has an equal chance of being on or off. The numbers show the number of lit strings.		Number   0     1     2     3   1-string Blinker off ON off ON 2-string Blinker off off ON ON
  COLORS MIXED FROM BLINKING 2-BRIGHTNESSES EACH OF RED, GREEN, AND BLUE RED 3 2 1 0 GREEN 3 2 1 0 3 2 1 0 3 2 1 0 3 2 1 0 BLUE 3                                 2                                 1                                 0

• Is there a cheaper way to make many colors in the room without a fader sequencer?

  Sequencers for mini Christmas lights have been available for about $10.

  Another way is to use one the old-style lamp flashers for each color string. Use loaded cords set for 15 watts to operate the flashers when using LED strings. If using single red, green, and blue strings, you can get red, yellow, green, cyan, blue, magenta, and white. Note that at times, all of the lights may blink off at the same time.

  To get more colors, use several blinking strings of each of the colors red, green, and blue. The colors mix to produce many pure and pastel colors. See the table above on the right and the table below it.

  For more colors, put two strings of one color on one blinker and one string of the same color on another blinker. Repeat this for all three colors. The lower table shows this.

  If mini incandescent strings are use used with flashers, the loaded cords are not required. But the blues will be very weak.

• How can a beautiful sunset effect on a self-lighted screen behind a tabletop nativity be done?

  The screen was translucent paper or screen material. Single color strings of red, green, and blue Christmas lights were placed near the top and the bottom of the screen, and adjusted with dimmers to produce a sunset effect. An opaque container behind the screen hid the lights. LED lights can be used with the loaded cords.

  An unchanging display could be made with a string of C7 Christmas lights behind the screen. Choose individual bulbs to get the color mixes wanted.

  It is possible to use a programmable light sequencer to create a repeating sunset, night, sunrise, and day sequence. This could also be used with a Christmas-town diorama.

• How do they make those huge Christmas displays that cover an entire house and lawn work?

  There are several ways to do it. Most of them cost a lot of money:

  • The simplest systems are basically many different independent small systems, such as individual chase sequencers for each separate item and self-contained displays.
  • A computer controlled power interface can be used to switch power outlets on and off or dim them according to a computer program. One such system is the old X-10 system.
  • A MIDI (Musical Instrument Digital Interface) light show interface can be used to synchronize lights to music. With multiple interfaces, many strings can be separately operated.
  • A custom designed one-of-a-kind system
• How large is the power consumption of a big light system?

  It can be calculated by the power used by each kind of light string:

  POWER CONSUMPTION BY NUMBER OF LAMPS AND LAMP TYPE
  			35-Light String				100-Lights				1000-Lights				10000-Lights
  Type	W		A	W	KW·hr/mo		A	W	KW·hr/mo		A	W	KW·hr/mo		A	W	KW·hr/mo
  C9 Inc	9 W		2.63 A	315 W	226.8		7.5 A	900 W	648		75 A	9000 W	6480		750 A	90000 W	64800
  C7 Inc	7 W		2.04 A	245 W	176.4		5.84 A	700 W	504		58.4 A	7000 W	5040		584 A	70000 W	50400
  C7 Inc	5 W		1.45 A	175 W	126		4.17 A	500 W	360		41.7 A	5000 W	3600		417 A	50000 W	36000
  T1.75 Inc	0.4 W		0.12 A	14 W	100.8		0.34 A	40 W	28.8		3.4 A	400 W	288		34 A	4000 W	2880
  T1.75 LED	0.069 W		0.02 A	2.4 W	1.73		0.06 A	7.2 W	5.19		0.6 A	72 W	51.9		6 A	720 W	519
  Key:			Red = multiple 200A services required								Amber = multiple 20A circuits required

  For the above table, a month is calculated as 30 days.

  The wattage drawn by all loaded cords used must be added into the total.

  If the lights are not on 24 hours a day, multiply the KW·hr/mo value by the fraction of a day the lights are on (e.g. 6 hours = .25).

• How much does all of this power consumption cost?

  Calculate the cost from the KW·hr/mo above by multiplying the usage by the cost per kilowatt hour:

  	COST PER KILOWATT·HOUR
  KW·hr	8 ¢	9 ¢	10 ¢	11 ¢	12 ¢	13 ¢	14 ¢	15 ¢	16 ¢	18 ¢	20 ¢
  1	$0.08	$0.09	$0.10	$0.11	$0.12	$0.13	$0.14	$0.15	$0.16	$0.18	$0.20
  2	$0.16	$0.18	$0.20	$0.22	$0.24	$0.26	$0.28	$0.30	$0.32	$0.36	$0.40
  3	$0.24	$0.27	$0.30	$0.33	$0.36	$0.39	$0.42	$0.45	$0.48	$0.54	$0.60
  4	$0.32	$0.36	$0.40	$0.44	$0.48	$0.52	$0.56	$0.60	$0.64	$0.72	$0.80
  5	$0.40	$0.45	$0.50	$0.55	$0.60	$0.65	$0.70	$0.75	$0.80	$0.90	$1.00
  6	$0.48	$0.54	$0.60	$0.66	$0.72	$0.78	$0.84	$0.90	$0.96	$1.08	$1.20
  8	$0.64	$0.72	$0.80	$0.88	$0.96	$1.04	$1.12	$1.20	$1.28	$1.44	$1.60
  KW·hr	8 ¢	9 ¢	10 ¢	11 ¢	12 ¢	13 ¢	14 ¢	15 ¢	16 ¢	18 ¢	20 ¢
  10	$0.80	$0.90	$1.00	$1.10	$1.20	$1.30	$1.40	$1.50	$1.60	$1.80	$2.00
  20	$1.60	$1.80	$2.00	$2.20	$2.40	$2.60	$2.80	$3.00	$3.20	$3.60	$4.00
  30	$2.40	$2.70	$3.00	$3.30	$3.60	$3.90	$4.20	$4.50	$4.80	$5.40	$6.00
  40	$3.20	$3.60	$4.00	$4.40	$4.80	$5.20	$5.60	$6.00	$6.40	$7.20	$8.00
  50	$4.00	$4.50	$5.00	$5.50	$6.00	$6.50	$7.00	$7.50	$8.00	$9.00	$10.00
  60	$4.80	$5.40	$6.00	$6.60	$7.20	$7.80	$8.40	$9.00	$9.60	$10.80	$12.00
  80	$6.40	$7.20	$8.00	$8.80	$9.60	$10.40	$11.20	$12.00	$12.80	$14.40	$16.00
  KW·hr	8 ¢	9 ¢	10 ¢	11 ¢	12 ¢	13 ¢	14 ¢	15 ¢	16 ¢	18 ¢	20 ¢
  100	$8	$9	$10	$11	$12	$13	$14	$15	$16	$18	$20
  200	$16	$18	$20	$22	$24	$26	$28	$30	$32	$36	$40
  300	$24	$27	$30	$33	$36	$39	$42	$45	$48	$54	$60
  400	$32	$36	$40	$44	$48	$52	$56	$60	$64	$72	$80
  500	$40	$45	$50	$55	$60	$65	$70	$75	$80	$90	$100
  600	$48	$54	$60	$66	$72	$78	$84	$90	$96	$108	$120
  800	$64	$72	$80	$88	$96	$104	$112	$120	$128	$144	$160
  KW·hr	8 ¢	9 ¢	10 ¢	11 ¢	12 ¢	13 ¢	14 ¢	15 ¢	16 ¢	18 ¢	20 ¢
  1000	$80	$90	$100	$110	$120	$130	$140	$150	$160	$180	$200
  2000	$160	$180	$200	$220	$240	$260	$280	$300	$320	$360	$400
  3000	$240	$270	$300	$330	$360	$390	$420	$450	$480	$540	$600
  4000	$320	$360	$400	$440	$480	$520	$560	$600	$640	$720	$800
  5000	$400	$450	$500	$550	$600	$650	$700	$750	$800	$900	$1000
  6000	$480	$540	$600	$660	$720	$780	$840	$900	$960	$1080	$1200
  8000	$640	$720	$800	$880	$960	$1040	$1120	$1200	$1280	$1440	$1600
  KW·hr	8 ¢	9 ¢	10 ¢	11 ¢	12 ¢	13 ¢	14 ¢	15 ¢	16 ¢	18 ¢	20 ¢
  10000	$800	$900	$1000	$1100	$1200	$1300	$1400	$1500	$1600	$1800	$2000
  20000	$1600	$1800	$2000	$2200	$2400	$2600	$2800	$3000	$3200	$3600	$4000
  30000	$2400	$2700	$3000	$3300	$3600	$3900	$4200	$4500	$4800	$5400	$6000
  40000	$3200	$3600	$4000	$4400	$4800	$5200	$5600	$6000	$6400	$7200	$8000
  50000	$4000	$4500	$5000	$5500	$6000	$6500	$7000	$7500	$8000	$9000	$10000
  60000	$4800	$5400	$6000	$6600	$7200	$7800	$8400	$9000	$9600	$10800	$12000

  For values between the table values, either interpolate the values or multiply the actual KW·hr/mo value by the cents per KW·hr.

• What is the maximum number or lamps that can be used?

  This depends on the kind of lamp and what it is connected to. A safety limit of 80% is applied, as required by the National Electrical Code:

  MAXIMUM SAFE NUMBER OF LAMPS
  ⇓ Lamp Type	Device ⇒		Individual circuit						200 A Service Entrance Capacity
  			13 A Ext Cord		15 A per Outlet		20 A per Breaker		200 A per Phase	400 A Both Phases
  	Safety Limit ⇒		10.4 A   1248 W		12.0 A   1536 W		16.0 A   1920 W		160 A   19200 W	320 A   38400 W
  9 W  C9 Incandescent			138		160		213		2133	4266
  7 W  C7 Incandescent			178		205		274		2742	5485
  5 W  C7 Incandescent			249		288		384		3840	7680
  0.4 W  T1.75 Incandescent			3120		3600		4800		48000	96000
  0.069 W  T1.75 LED			17300		20000		26600		266600	533300
  Max KW·hr per month			929		1143		1429		14285	28570

  Of course, the ratings on any controller must also be obeyed. It is a very good idea to limit loading of controllers to 80% too.

  Also, you must remove capacity used by normal life in the house (and leave some extra for new Christmas gifts).

• Can more lights be added to a circuit by using twinkle bulbs?

  No. There are two things wrong with this twinkle kind of thinking:

  • All twinkle bulbs start out in the ON state, tripping the breaker when lights are first turned on.
  • Although rare, it is possible that too many of the bulbs can blink on at the same time. This would also trip the breaker.
• Why does the main breaker trip, even though none of the 20 amp circuits are overloaded?

  The total load is more than the limit on the main breaker. Check these things:

  • Are all of the lights on one phase of the service entrance? Make sure circuits for the lights come from both phases.
  • Is the total current draw higher than the rating of the main breaker?
  • Does this happen when other appliances are also turned on? If so, the appliance(s) and the lights together are overloading the service entrance.
• What is the best way to distribute power to a large Christmas light system?

  It is NOT using lots of power strips or extension cords running room to room. The following list shows the proper way to do it:

  • All wiring should conform to the National Electrical Code, and with any laws that apply.
  • Circuits added for the display should be balanced between phases A and B in the breaker box.
  • Separate switched 20 A circuits should be run to each major controller device.
  • If the controller works with a GFCI, the circuit should have a GFCI breaker.
  • If the controller trips a GFCI, the reason should be determined. Often older devices were made with noise reduction in mind, not GFCI protection. If a device is used without a GFCI, its wiring must be kept out of reach of strangers.
  • Controller devices should be indoors. They can be all in one room, or be placed in rooms closest to what they control.
  • Each outlet controlling Christmas lights should have its own switch.
  • Separate switched 20 A circuits should be provided for self-contained decorations (e.g. inflating figures).
  • Special permanent transfer circuits should be installed to carry current from controllers to the outdoor lights they control:
    • The indoor end of each transfer circuit needs either a pendant cord and plug, or a plug in the electrical box capable of taking a matching socket on a small removable cord.
    • Each transfer circuit should be fused to protect the controller and the cords.
    • Each transfer circuit's outdoor outlet should have its equipment ground connected to the equipment ground of the outlet powering the controller. Removing the controller should not disconnect the equipment grounds.
    • Each transfer circuit should end outdoors in a weatherproof box with a weatherproof in-use cover.
    • Each transfer circuit outdoor outlet must be marked as not for normal power use. The box should be painted a different color.
    • Good places to mount outdoor transfer boxes include under soffits, on riser posts, and behind bushes. Do not mount them at ground level or let foliage contact them.
  • Enough GFCI-equipped normal power outlets should be provided for outdoor electric appliances (e.g. electric mower) so workers don't try to use the special sockets
  • Outdoor junctions must be made inside sealed or otherwise weatherproof containers. Plastic covers are sold for this.
  • It might be a good idea to recess a covered wire tray into the ground where multiple cords make the same run. But make sure the space around the tray is arranged to drain away rainwater.

    A wire tray could also be put under the roof soffits.

  • Do not use zip-cord for outside connections. Use covered 3-wire cords.
  • Floodlights that do not have to be specifically positioned and which do not use a controller should be permanently wired in place.
  • Switches that turn on decorations should be marked for their purpose and should be a color different from the switches that control normal house functions. These switches could be grouped together on one large panel.
  • Do not use circuit breakers as switches.
  • Timers should be indoors, and should also use transfer circuits.
  • Be sure to calculate the wattage of each string, of cascaded strings, of cords, of outlets, of breaker box circuits, and of the entire house.
  • Don't connect so much display equipment that normal life in the house is prevented due to electrical usage or lack of outlets.
• What can deter thieves from stealing Christmas lights?

  Criminals steal because they hate doing work. They don't want to work for what they have. Making theft require a lot of work deters theft.

  Put lights in places high enough that the thieves can't easily reach them.

  Put lights inside the house, showing out the windows.

  Tie the lights to the surfaces they are on.

  Mix up some white grease and cayenne peppers. Paint a little on each bulb husk. That thief will never do it again.

• What can deter squirrels from chewing off Christmas bulbs?

  Mix up some white grease and cayenne peppers. Paint a little on each bulb husk.

  Put lights inside the house, showing out the windows.

  Put the lights where squirrels can't go.

• How are Christmas decorations that are drawings made in lights made?
  

  Some of these are displays purchased from stores.

  For homemade ones, do the following:

  • Get a piece of 1/2 inch thick foam filled art mounting board. 1/4 inch board usually is not strong enough.
  • Find the strings of lights (and a controller, if used) you wish to use. The best lights are usually the long T-1.75 LEDs.
  • Sketch the wanted design on the art board. Lines should be far enough apart that lights are not crowded together.
  • Design the light pattern, including where the different strings of lights will go. Put dots on the art board where the lights will go.
    • Do not design the display to use all of the lights in the string.
      There may be places where the distance between lamp locations is longer than the distance between lamps in the string.
      Also, the failure of a single nonremovable bulb would require replacing the entire string, unless spares are interspersed in the wiring behind the display.
    • Don't space lamps so far apart that the wires are stretched to their limits. A replacement string might not have as much space between the lamps.
  • Note that some lamps have removable covers.
    Remove the covers, and make the holes in the board small enough to hold the lamp with the cover removed. Put the covers on after the lights are mounted.
  • Push a pencil through the art board where each light belongs.
  • Push the lights through the art board from the back side.
  • Mount the display in the window. Often curtains can hold it in place.
  • Connect the lights up, using a controller if intended.

  The photo at right is a time exposure of such a display made by the page author using C9-sized LED bulbs. The time exposure was needed because the lights are sequenced by a controller.

• How can a set of chase lights that go around a roof be made?

  Such strings can be bought.

  A sequencer with four light outputs is needed. It must give a 1, 2, 3, 4 sequence.

  Four identical strings of LED lights can be bound together with twist ties so the lamps stay in the proper sequencing order. Additional identical strings can be attached to the ends and tied in the same manner.

  This can be done with three strings and a three-output sequencer, but the effect is better with four strings.

  A better sequence can be had if the sequencer can do a 1+2, 2+3, 3+4, 4+1 sequence.

  Other good chase sequences are:

  • 1, 1+2, 2, 2+3, 3, 3+4, 4, 4+1
  • 1, 1+2, 2, 2+3, 3, 3+1 (3-string)

  Sequence your Christmas Lights

• How was the swinging bell effect in this photo done?
  

  The upper photo is a time exposure. Only one color is lit at any one time.

  The lower animation was reconstructed from the upper photo through editing.

  It was extremely difficult to take matching photos to make the animation from due to different exposure levels. The photos obtained that way were not usable.

  At the time this page was constructed movies were not allowed in my old hosting site, so I used .gif animation.

  The colors light in the red, white, blue, white, red, white, blue, white sequence. This makes the bell look like it is swinging back and forth, as seen in the animation below.

  The display was made the same way the tree display above was, with an art board.

  A piece of wire was bent into the shape of the bell and used to sketch three bell shapes on the art board. Then the locations of the lamps were marked so they would not interfere with each other and holes were made in the art board for the lamps.

  The LEDs are the C5 size, but the size of the entire display can be changed to use any size of LED bulb.

  Note that the clapper is in a different position in each bell, simulating the position of the clapper in a real bell.

  Each clapper is a tight grouping of four LED lights (blurred by the time exposure and overexposed and blended into one large spot).

  When seen at a distance, the swinging bell effect is more pronounced.

  The sequencer used is one that uses an oscillating pattern. The outputs are sequenced to light in a 1, 2, 3, 2 repeating pattern. The speed of the sequencer can be changed to make the swinging effect go faster or slower.

  Each color of lights is a different string of lights.

  The blue lights are actually brighter than they appear in the image here. The design of a color monitor subdues the blue. All three colors appear roughly the same brightness when the actual display is viewed.

  If desired, all of the lights can be the same color. Red is a good suggestion.

  Each bell has 30 LEDs (the original size of the first red strings used). When brighter and blue LEDs became available, sets with 45 LEDs were substituted. The extra LEDs were hung behind the art board where they cannot be seen from outside.

  The page author originally had the idea of using some kind of sequencer to make bells look like they were swinging at age 12. The bells he saw were a cluster of three bells with flasher lamps in them, so they lit and darkened randomly. The only sequencers available then were expensive chase-light units for theater marquees. When sequencers became easy to make, the page author realized that his idea could be built.

  Other patterns, such as a walking man, a size-changing star, or a waving flag, can use the same animation technique.

  Sequence your Christmas Lights

• How can a spinning 8-point star be done?
  

  The star is similar to the one at below right, but all 8 points of the star are similar to the diagonal points in the photo. The opposite points of the star are parts of the same string of lights. The four strings are connected to a 4-output sequencer.

  A six-pointed star can be done with a 3-output sequencer.

  The sequences listed as best for chase lights also work best here.

  Sequence your Christmas Lights

  The image at right has several sequences that are best for chase or rotating lights. The sequences are:

  1, 2, 3	R, G, B	1, 2, 3, 2	1, 2, 3, 4	1, 2, 3, 4 ,3, 2,
  123 Walk	RGB Walk	RGB 7	1234 Dual	1234 Walk

  • Walk sequences are of the form: 1, 1+2, 2, 2+3, 3, 3+1
  • Dual sequences are of the form: 1+2, 2+3, 3+4, 4+1
  • The 7 sequence is: R, R+G, G, G+B, R+G+B, B, B+R
• How does the star-cross in the photo at right shimmer to different brightnesses?
  

  There are several methods that can be combined to do this:

  • Shimmer devices are available over the counter.
  • A special circuit using twinkle bulbs
  • The page author's version has two different light strings with two different shimmer circuits:
    1. One string lights all of the doubled lights to make the thick parts of the cross.
    2. The other string has the diagonal rays, the center LED, and the tips of the cross.
  • Two 40-light half-wave strings are used.

    -- Both parts are used for Christmas.
    -- The thick cross part is used alone for Easter.

  • This display was made using art board.
  • This display is held in the window by placing it between the window and the curtains.
  • Each string of lights in the display has 3 light levels

    -- off
    -- dim
    -- bright

  • There are a total of 9 different lighting conditions.
  • The upper image is a time exposure. The lower image is an animation.
  • The animation was made to show typical operation using the twinkle-bulb device.
  • A fireplace effect could be made from many copies of this effect with various fire-colored strings.

  Imagination can provide several other similar uses for this.

• How can LED strings and sequencers be protected from surges and RF noise?

  Buy surge protector power strips and add one .1 μF 600 V capacitor across the hot and neutral leads of the outlets of each strip.

  Do not connect any capacitors between the hot or neutral lines and the equipment ground.

  Clamp-on ferrite filters placed ahead of the power strip and capacitor add further protection.

• How can noise from LED strings, lamps, or sequencers be kept off the power lines?

  Buy surge protector power strips and add one .1 μF 600 V capacitor across the hot and neutral leads of the outlets of each strip.

  Clamp-on ferrite filters placed on the power strip cord and on the cord of the LED or sequencer add further reduction of noise.

• How can radio frequency interference (RFI) from LED strings, lamps, or sequencers be stopped?

  Buy surge protector power strips and add one .1 μF 600 V capacitor across the hot and neutral leads of the outlets of each strip.

  Clamp-on ferrite filters placed on the power strip cord and on the cord of the LED or sequencer add further reduction of RFI.

• How can the above capacitors be kept from absorbing carrier current signals for wireless controls or speakers?

  Put a clamp-on ferrite filter on the power strip cord.

  Place a long extension cord between the power socket and the power strip with the capacitor.

• How can Christmas lights be protected from static electricity from lightning?

  A grounded antenna tower or grounded drain wires much higher than the lights can greatly reduce static electricity fields.

• Can Christmas lights be protected from induced currents from lightning?

  This would be extremely hard to do. A grounded shield would be needed.

  Such currents do not flow unless an open loop of wire exists, or a discharge point exists at the end of a long run of wire.

  Currents cannot be induced in wires inside metal conduits.

  Put a clamp-on ferrite filter on the string power cord next to the plug.

• How do the color-changing fiber optic systems work?

  All of the fibers are gathered and fused into a large transparent plastic end inside the case.

  A bright light shines through a rotating color wheel and onto the large end. The light is then distributed to all of the individual fibers.

  Stripes and other shapes on the color wheel make the pretty twinkling patterns in the fibers.

  Some units have multiple flashing 7.5 watt bulbs instead of a color wheel.

  Some units have multiple LEDs operated by a sequencer.

• Is there any way to reduce the almost dangerous heat coming from the fiber-optic system case??

  Yes. Replace the halogen bulb with an equivalent replacement LED bulb having an equal or greater lumen rating. It runs much cooler, and the display may even be brighter.

  The page author replaced a 20-watt halogen reflector bulb with a 5-watt LED with a lumen output equivalent to a 50 watt bulb. The results were very good. The case does not get hot, and the display is brighter.

  It is a good idea to place a 1.5 amp fuse in series with the transformer output to protect it if the LED shorts when it burns out. The page author learned this the hard way.

• How do displays that make white spots of "snow" seem to fall down the side of a house work?

  A small box placed in the yard contains a spotlight and a small mirrored disco ball. The ball is mounted on a horizontal axle driven by a geared-down motor. The motor rotates so the side of the ball facing the house moves downward. The light of the spotlight reflects from the facets of the ball, producing the dots. Rotation of the ball makes them move downward.

  NOTE: Some newer units have colored LASERs instead of spotlights. These must not be allowed to shine into the sky, because LASER light can blind airplane pilots. Also, do not look into the LASER beams coming from these devices.

  ALSO NOTE: Some even newer units have colored LEDs instead of LASERs. These do not cause the hazards the LASER ones cause and can produce more colors.

• How do they make those displays that look like a see-through cone "tree" standing in an empty part of a yard?

  This is a series of strings of lights attached to a flagpole. Strings of lights somewhat longer than twice the height of the flagpole (and all the same length) are used. A circle is laid out around the flagpole. The ends of each string are anchored at opposite sides of the circle. The midpoints of all of the strings are tied together and attached to the flagpole lanyard. Then the lanyard is used to hoist the string midpoints to the top of the flagpole. Tying off the lanyard at the cleat keeps the lights hoisted.

  How the light strings are operated depends on budget and equipment available. The simplest way to operate them is to use a sequencer, and connect every 4th string to the same output. Or a large controller can be used to put many patterns into the lights.

  A device called a Tree Dazzler can be used with a 7-foot pole as well as with a tree. But it is for indoor use only.

• How can I get lights up in a large tree and down again without a tall ladder?

  Use a long pole with a hook on the end of it.

  Run each string over the top of the tree (or up to a point near the top) and down again, rather than trying to wind strings around the tree.

• How do some people make the entire top of an outdoor tree glow, sometimes in different colors, without light strings up in the tree?

  This trick is accomplished with one or more colored floodlights or spotlights. To hide what is done, the floodlights are hidden inside fake stumps or behind other decorations.

  This trick could also be done with the color wheel lamps below if they are waterproof.

  A sequencer could control several different colored spotlights.

• How did they make entire white or silver Christmas trees change color in the 1960s??
  

  A floodlight with a rotating color wheel was aimed at the tree. These were sold just for the purpose of lighting artificial trees that would be dangerous if used with the C7 and C9 bulbs available at that time.

  • The white trees were plastic, which the large lamps available then would melt or burn.
  • The silver trees were aluminum with metal needles, which could short to the screw shells of the lamps, electrifying the tree. The screw shells were designed to keep fingers out, not tiny metal needles. Since plugs were not polarized in the 1960s, this would have been very dangerous.

  The solution was to provide a light source away from the tree. The usual colors on the wheel were red, green, orange-yellow, and blue.

  The floodlight and color wheel did this job until the mini lights appeared on the market. The mini lights are fully insulated and don't get hot enough to damage a plastic tree.

  Some people used two or three of these color wheels to make a multicolored display. Special wheels with only red, green, and blue segments were made for this purpose.

  Note that the color wheel devices were usually not weatherproof.

• What are the old Christmas lights with pointy bulbs and miniature (C6) bases?

  These are series Christmas lights sold in the 1910s to the 1950s. Most of them had eight 15-volt lights.

• What are the different lamp and base sizes?
  

  There are several E-type (Edison screw base) sizes.

  • E10 - miniature - old series C6 strings, flashlight bulb (left bulb in image)
  • E12 - candelabra - C7 lights (center bulb in image)
  • E17 - intermediate - C9 lights (right bulb in image)
  • E27 - medium - standard light bulb socket used for large over-the-street strings
  • E40 - mogul - lamps over 300 watts (rare)

  These sizes have been around since the beginning of the manufacture of incandescent lamps.

  The subminiature socket for T1.75 Christmas lights seems to have been created for the purpose of making Christmas light strings.

Links:

Christmas Light Devices

Make Christmas Lights Shimmer

Sequence your Christmas Lights

Christmas Light Tester for Special Device use

Light Bulbs, Spectra, and Vision