St Francis Consolidated RR Look, I'm not an electrician or electrical engineer like a few of you, and, although I was in Jesuit formation for four years I am no brother in a monastery like the LION, but I don't get it........ Why is a string of Christmas lights that is perfectly safe plugged into the wall and running around your tree and house perfectly safe, but the same string of lights (even extended with a little of the same wire) is somehow dangerous because it's plugged into a wall and used on a mrr layout? Seriously, am I missing something here???
Look, I'm not an electrician or electrical engineer like a few of you, and, although I was in Jesuit formation for four years I am no brother in a monastery like the LION, but I don't get it........
Why is a string of Christmas lights that is perfectly safe plugged into the wall and running around your tree and house perfectly safe, but the same string of lights (even extended with a little of the same wire) is somehow dangerous because it's plugged into a wall and used on a mrr layout?
Seriously, am I missing something here???
For me, the concern is to cut and splice between all of those bulbs and end up with accidentally exposed/weakened wire. Also, given the nature of working under layouts with many wires, you would not want to accidentally cut into 120V live wire. Just a few reasons that quickly come to mind, there are others I suspect.
If you wanted to hang a string of lights up out of the way where they won't be rubbed or accidentally cut, etc that is what their designed for.
Richard
St Francis Consolidated RR Why is a string of Christmas lights that is perfectly safe plugged into the wall and running around your tree and house perfectly safe, but the same string of lights (even extended with a little of the same wire) is somehow dangerous because it's plugged into a wall and used on a mrr layout?
Two possible answers:
1) You still have 110 Volts AC in the wiring, and having a lot of splices in that wiring leads to more chances of electrical shock if they are not done properly.
2) If one of the wires is not spliced properly because you cut all 3 at the same spot and get them mixed up, you could cause a fire.
If you've never been near an LED that exploded because an improper voltage was applied to it, you haven't lived. The shattering plastic could very easily put an eye out. They also give off a very noxious smoke.
IF you ran the line UNDER your layout and extended the individual lights up through the benchwork, you should be ok. I think what the previous concerns have been, would be the routing of the 110 volt line ON the benchwork where there might be a danger to driving a spike or something into the line !
Two important factors you need to adhere to .... use the same gauge wire to extend any leads, solder them and cover them with shrink tubing. When cutting the socket from the set, make certain your extensions re-attach in the exact same orientation as is was to begin with.
Lastly, DO NOT add or remove the number of LEDs in the string. They are designed with a specific number of LEDs to function properly on line voltage. Adding more LEDs, and they probably won't work .... take any out, they will all self destruct.
Mark.
¡ uʍop ǝpısdn sı ǝɹnʇɐuƃıs ʎɯ 'dlǝɥ
[quote user="Mark R."]
Train Modeler: nedthomas: LEDS work fine on AC. They just light every half cycle, 60 times a second. I guess that depends on your definition of fine. Richard
nedthomas: LEDS work fine on AC. They just light every half cycle, 60 times a second.
LEDS work fine on AC. They just light every half cycle, 60 times a second.
I guess that depends on your definition of fine.
Using the appropriate resistor, try an LED on 12vdc and 12vac - I bet your eye cannot dicern the difference. Remember bi-color red / green leds - forward bias dc gives you green, reverse bias dc gives you red and applying ac would light both the red and green due to the ac voltage providing an alternating bias cycling at 60 times per second giving what appeared to be a yellow indicator. This was done in an MR article probably twenty years ago !
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Good point that it will work, but even though you won't look at Christmas lights as you do a computer screen, after a while that flashing is not good for your eyes(even though you can't discern it--you're right at least I can't). Also, it is not optimal for LED life. But, running them on AC seems more efficient.
The St. Francis Consolidated Railroad of the Colorado Rockies
Denver, Colorado
Good points.
BroadwayLion Train Modeler: The 120V is likely stepped down and rectified somewhere, LEDs don't like 120V and they don't work on AC. The 3 wires are so that you can have an LED blow out and keep the others lit. You can take a meter and check for voltage and polarity within the string where you want to add wire length to verify, then splice in according to what length you want(within reason, not like adding 100 feet to the string). These splices IMHO should be soldered and shrink wrapped to support the string weight. But, if the string truly has 120V(which I doubt) throughout its' length--I wouldn't put it around the layout where accidents can happen. Also, are you sure the lights are LEDs, mine are bulbs and run on 3.5V. Seriously though, the fact you're asking this question and it being a 120V system makes me nervous. Richard There are no transformers. They are wired in series, and there are a few resistors so small you can hardly see them. There may be rectifiers either in the plugs or in a wart on the line, or they can just be on AC, you will see them flickering more. The LION throws away the wires and sockets and keeps the lamps. ROAR
Train Modeler: The 120V is likely stepped down and rectified somewhere, LEDs don't like 120V and they don't work on AC. The 3 wires are so that you can have an LED blow out and keep the others lit. You can take a meter and check for voltage and polarity within the string where you want to add wire length to verify, then splice in according to what length you want(within reason, not like adding 100 feet to the string). These splices IMHO should be soldered and shrink wrapped to support the string weight. But, if the string truly has 120V(which I doubt) throughout its' length--I wouldn't put it around the layout where accidents can happen. Also, are you sure the lights are LEDs, mine are bulbs and run on 3.5V. Seriously though, the fact you're asking this question and it being a 120V system makes me nervous. Richard
The 120V is likely stepped down and rectified somewhere, LEDs don't like 120V and they don't work on AC. The 3 wires are so that you can have an LED blow out and keep the others lit. You can take a meter and check for voltage and polarity within the string where you want to add wire length to verify, then splice in according to what length you want(within reason, not like adding 100 feet to the string). These splices IMHO should be soldered and shrink wrapped to support the string weight. But, if the string truly has 120V(which I doubt) throughout its' length--I wouldn't put it around the layout where accidents can happen. Also, are you sure the lights are LEDs, mine are bulbs and run on 3.5V.
Seriously though, the fact you're asking this question and it being a 120V system makes me nervous.
There are no transformers. They are wired in series, and there are a few resistors so small you can hardly see them. There may be rectifiers either in the plugs or in a wart on the line, or they can just be on AC, you will see them flickering more.
The LION throws away the wires and sockets and keeps the lamps.
ROAR
LED Christmas light strings are wired in the exact same manner as the bulb variety. Depending on the material the LED is made from (which designates the color) white LEDs require 3.4 to 3.7 volts to operate at full potential. In the case of the OP's light string of LEDs, there would be 30 LEDs wired in series (30 LEDs X 3.7 = 111 volts) parallelled with another series string of 30 LEDs - hence the third wire. No wall warts, rectifiers or resistors required. If there is a resistor with each LED, it would be a minimal value like 10 ohms to help account for variations in line voltages which are common in rural areas.
There's no transformer or rectifier in those LED light strings. The simpel expeient of having 2 LEDs wired back to back makes them work fine on AC - that way neither LED sees a high reverse voltage, which would otherwise quickly destroy an LED - instead it sees teh forward voltage of its partner LED as the reverse voltage. The, string enough pairs together in series and it'sll work on 120VAC.
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
Train Modeler nedthomas: LEDS work fine on AC. They just light every half cycle, 60 times a second. I guess that depends on your definition of fine. Richard
nedthomas LEDS work fine on AC. They just light every half cycle, 60 times a second.
Train Modeler The 120V is likely stepped down and rectified somewhere, LEDs don't like 120V and they don't work on AC. The 3 wires are so that you can have an LED blow out and keep the others lit. You can take a meter and check for voltage and polarity within the string where you want to add wire length to verify, then splice in according to what length you want(within reason, not like adding 100 feet to the string). These splices IMHO should be soldered and shrink wrapped to support the string weight. But, if the string truly has 120V(which I doubt) throughout its' length--I wouldn't put it around the layout where accidents can happen. Also, are you sure the lights are LEDs, mine are bulbs and run on 3.5V. Seriously though, the fact you're asking this question and it being a 120V system makes me nervous. Richard
The Route of the Broadway Lion The Largest Subway Layout in North Dakota.
Here there be cats. LIONS with CAMERAS
Those LED strings are a combination of series / parallel wiring - if you mess up the sequence they are wired in, you could be in trouble.
To answer the question: If you know what you are doing, any reasonable length is fine.
If you don't know how to make safe splices or what gauge wire to use or have ANY question about how to do this then you shouldn't.
Be aware that by modifying the string you will invalidate the UL or CSA "listing".
The mind is like a parachute. It works better when it's open. www.stremy.net
Break them up and use them like indivdual LEDs. Do NOT try to splice in extra wire then plug the whoel thing in to a wall outlet. Too dangerous. The only thing plugged in to wall outlets for your layotu should be UL listed transformers and power supplies. Only LOW voltage strung around the layout, please.
iwander I have several sets of led Christmas lights. 60 bulbs 3 wires with 120 ac plug. How much extra wire can I add to the set before it blows? I don't want lights below the train board but they are only 5 inches apart. I want to add wire between some bulbs. How much is safe?
I have several sets of led Christmas lights. 60 bulbs 3 wires with 120 ac plug.
How much extra wire can I add to the set before it blows? I don't want lights below the train board but they are only 5 inches apart. I want to add wire between some bulbs. How much is safe?
GACK!
Are you working with a 120 volt set? LION would not play with those.
The LION takes the LEDS out of the wires and holders. He keeps the LEDs and discards the rest. Now he has pile of LEDs on his counter. One leg is (+) the other leg is (-). Add a 1000 ohm resistor to the circuit and you can light the led with 12 volts from your train transformer. If it does not light one way turn the lamp around and it will work the other way.
LION uses these for signals, for station lighting, for the control panel, and for car lights.
Here is one of my stations.